REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
COPYRIGHT 2002 BY QUINTESSENCE PUBLISHING CO, INC.PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART OF THI
TOPICAL REVIEW Complex Regional Pain Syndrome in the Head and Neck: A Review of the Literature This article reviews the features of complex regional pain syn-drome (CRPS), including its pathophysiology, diagnosis, andtreatment. CRPS is a pathology that has been described as occur-ring almost always in a limb, but this review provides a focus onthe literature reporting cases in which the face, head, and neckwere affected. Very few cases were found that seemed to meet theInternational Association for the Study of Pain criteria for the dis-ease. The clinical characteristics were similar to those of CRPSelsewhere in the body, with the main features being burning pain,hyperalgesia, and hyperesthesia starting after a trauma to the cran-iofacial region. Physical signs were reported less frequently. Thetreatment of choice was seen to be a series of stellate ganglionanesthetic blocks, which resulted in a good outcome in all thecases reviewed.Key words:
causalgia, complex regional pain syndromes, facial
pain, facial pain syndromes, reflex sympathetic dystrophy
Tufts UniversitySchool of Dental MedicineBoston, Massachusetts
Noshir Mehta, DMD, MDS, MSProfessor and ChairmanDepartment of General Dentistry
The term causalgia,now called complex regional pain syn-
drome (CRPS) type II, was first described by Mitchell etal1,2 in 1867 when they reported cases that occurred during
the American Civil War. Soldiers who had sustained nerve injuriespresented with intense burning pain and hypersensitivity to light
mechanical stimulation, and the skin on the area of the lesion was
red, hot, and shiny. Soldiers who had undergone surgical limbamputation reported similar symptoms at the stump end.2,3 Cases
occurring during World War II were reported later by Leriche.4,5
He described some pain relief obtained in these patients after strip-
ping the sympathetic plexus from major arteries. The term reflexsympathetic dystrophy (RSD), now called CRPS type I, was pro-
posed by Evans6 in 1946. This term implied an autonomic compo-
nent affecting pain severity and trophic changes in the soft tissues.
Most of the cases of CRPS reported in the literature refer to
limb injury, and very few cases are described occurring in the head
and neck region. Accordingly, this review will focus on CRPS
School of Dental Medicine1 Kneeland Street
from an orofacial pain point of view, citing and discussing all the
cases reported to date in the literature.
Fax: +(810) 885-7485E-mail: [email protected]
A new classification of chronic pain by the InternationalAssociation for the Study of Pain (IASP)7 had the purpose of sim-
REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
COPYRIGHT 2002 BY QUINTESSENCE PUBLISHING CO, INC.PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART OF THI
plifying diagnosis of traumatic neuralgias—to
overcome the confusion created by the previously
6. Changes induced in the CNS12,13,15,23–29
used terms reflex sympathetic dystrophy and
After nerve injury, primary afferent neurons
causalgia—and of recognizing the fact that the
undergo biologic changes that lead to abnormal
influence of the autonomic nervous system on the
disease is far from clear. The new name created is
discharge9,30; in fact, spontaneous firing of noci-
complex regional pain syndrome. Two types of
ceptive C-fibers and mechanoceptive Aß-fibers has
CRPS have been proposed: CRPS type I (RSD) and
been described.14 These observations would
CRPS type II (causalgia). Both terms refer to a syn-
explain some of the clinical symptoms reported by
drome characterized by spontaneous pain or allo-
dynia and hyperalgesia, not limited to the territory
The presence of ephapses between nerve fibers
of a single peripheral nerve, and associated with
has been reported.16 This abnormal connection
edema, abnormal skin blood flow, or abnormal
allows transfer of stimuli from one nerve fiber to
sudomotor activity. The difference between the 2
another with cross-activation of neural pathways.
types resides in the fact that in CRPS type II
Such coupling would tend to amplify both ectopi-
(causalgia), a lesion of a major nerve is reported,
cally and naturally generated impulse activity15
while an unspecified noxious event precedes CRPS
and might be responsible for increased pain per-
ception (allodynia, hyperalgesia, hyperpathia) in
The influence of the autonomic nervous system
on the pain is considered separately from the type
Gregg12 observed nerve collaterals in association
of CRPS. Response to a sympatholytic procedure
with zones of previous trigeminal nerve injury;
such as a stellate ganglion anesthetic block is used
these collaterals derived either from the proximal
to differentiate between sympathetically main-
trunk of the same injured nerve or, in other cases,
tained pain (SMP) and sympathetically indepen-
from adjacent nerves. Woolf et al32 also described
dent pain (SIP); this is in addition to and indepen-
sprouting of A-fibers into lamina II of the dorsal
dent of the diagnosis of CRPS type I or II.9,10
horn of the spinal cord. What might happen isthat, after this neural rewiring, lamina II, whichusually receives only nociceptive inputs, will
receive also non-nociceptive inputs that may bemisinterpreted as noxious13 and thereby cause pain
The mechanism by which pain and the other phys-
even when light touch or pressure is applied to the
ical abnormalities develop in CRPS is not fully
skin (allodynia). In other cases, activation of the
understood. Trauma seems to be the precipitating
second-order neurons in the dorsal horn might be
factor, causing damage to a peripheral nerve and
due to release of substance P and calcitonin gene-
inducing neurobiologic changes in both peripheral
related peptide from normally non-nociceptive A-
and central components of the nervous system.
fibers after a phenotypic switch in these fibers fol-
This is considered to reflect a deafferentation
mechanism that produces abnormal afferent input
In 1944, Granit et al17 suggested that a short-
into the central nervous system (CNS), which
circuiting phenomenon develops where collateral
causes a painful sensation independent of or not
sympathetic efferents synapse with afferent sensory
proportional to any actual noxious stimuli applied
fibers at the site of injury.22 After partial nerve
injury, sensory axons begin to express ß-receptors
The following modifications in the neural tissue
on their membrane and become sensitive to circu-
have been observed and studied to try to under-
lating catecholamines, and the same modification
stand the mechanisms through which pain is per-
has been seen in the dorsal root ganglion neu-
rons.9,13,22,35 Moreover, nerve injury induces
1. Sensitization of nociceptive fibers9,13,14
sprouting of sympathetic efferents around the cell
2. Cross-activation between injured afferent fibers
bodies of sensory neurons in the dorsal root gan-
glion.9,20–22 The influence of sympathetic activity
3. Sprouting of somatic afferent fibers from adja-
on peripheral afferents may also occur indirectly
when the release of norepinephrine stimulates the
4. Activation of afferent fibers by sympathetic
release from postganglionic sympathetic terminals
of prostaglandins that sensitize sensory affer-
REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
COPYRIGHT 2002 BY QUINTESSENCE PUBLISHING CO, INC.PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART OF THI
ents.22,36 All these phenomena would lead to exci-
tation of pain fibers by outgoing sympathetic
central nociceptive neurons seem to be responsible
impulses,18,19 a mechanism that is thought to occur
for some of the clinical characteristics of neuro-
pathic pain. Activation of these receptors requires
After nerve injury, if the nerve sheath has been
a prior activation of an amino-3-hydroxy-5-
damaged or displaced, the sprouting neurons will
methylisoxazole-4-proprionic acid (AMPA) or
likely grow with a chaotic organization, which is
metabotropic receptor that causes expulsion of
called a neuroma. It is not a true neoplasm, but a
magnesium ions from the NMDA receptor. After
disorganized structure that includes axoplasmic
stimulation by glutamate, this allows opening of
elements, myelin, Schwann cells, and connective
the calcium-ion channels that depolarize the neu-
tissue elements.11,15,37 Neuromas are extremely
ron. Calcium also stimulates intracellular synthesis
sensitive to norepinephrine released by sympa-
of nitric oxide, which diffuses out of the neuron
thetic efferents in the area of the lesion38 and can
and causes ongoing presynaptic excitation and
produce spontaneous continuous pain as well as
release of more glutamate.11,13,60 The phenomenon
episodic pain triggered or aggravated by pressure
of central sensitization that follows is a reflection
or tension.11 Axons that have been demyelinated
of so-called “neuroplasticity” and is associated
may also become hyperexcitable and show sponta-
with increased neuronal excitability, hyperalgesia,
neous impulse discharge, mechanosensitivity, and
rhythmic after-discharge in response to mechanical
The different mechanisms listed above are not
and electrical stimuli.39–41 Their discharge pattern
mutually exclusive, and more than one is likely to
is very similar to the pattern of axons associated
occur in the peripheral nervous system and CNS
with neuromas, but the latter are usually more
after partial or complete nerve lesion.
In addition to pain, other abnormalities are seen
The possibility that central changes in neuronal
in CRPS, and some of them are believed to be
excitability occur after damage in the periphery
related to an altered function of the sympathetic
makes plausible the hypothesis that the CNS is
system. These are edema, which may be dimin-
involved in the origin of the continuous pain.42
ished after sympathetic block,61 and abnormalities
After nerve injury the trigeminal ganglion under-
in sudomotor activity and skin blood flow. It is
goes a certain degree of cell loss43,44 involving mas-
thought that the vasculature develops an increased
sive degenerative responses in the central fiber pro-
sensitivity to local cold-temperature stimuli and
jections to the trigeminal spinal nuclei45,46; this
catecholamines9; this has been shown experimen-
deafferentation process has been reported to initi-
tally by testing the thermoregulatory response to
ate secondary changes in the receptive zones of the
skin cooling and warming, and suggests that both
brain stem where neurons become tonically hyper-
an inhibition and an activation of sympathetic
active,28 but it is unclear whether these changes
occur to a significant degree in trigeminal brain
Trophic changes such as abnormal nail growth,
stem nociceptive neurons.47–49 On the other hand,
increased hair growth, palmar and plantar fibrosis,
sensory cells located in the dorsal root ganglia and
thin glossy skin, and hyperkeratosis have been
in the cranial nerve ganglia are normally intrinsi-
hypothesized to have an inflammatory pathogene-
cally rhythmogenic,50,51 but the magnitude of dis-
sis,9 and scintigraphic investigations strongly sup-
charge is augmented significantly by chronic nerve
port an inflammatory component in CRPS.22,62
Other changes may occur at other sites in the
CNS. Livingston27 suggested that a constant
source of pain would trigger a reverberating pat-tern of firing in the internuncial pool in the dorsal
The clinical presentation of CRPS patients is very
horn of the spinal cord, so that the neuronal activ-
heterogeneous. Pain is the prevalent symptom, but
ity would then become self-perpetuating and cause
its characteristics can vary substantially. It can be
the pain to persist.26,53 Recent studies54–59 suggest
spontaneous as well as evoked by stimuli, continu-
ous as well as episodic or paroxysmal. The quality
involved in the development and maintenance of
can be burning, shooting, throbbing, pressing, and
neuropathic pain, particularly those involving the
aching. The location of the pain is usually deep
role of interleukins and tumor necrosis factor.
inside the distal part of the affected extremity, and
REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
COPYRIGHT 2002 BY QUINTESSENCE PUBLISHING CO, INC.PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART OF THI
Somatic CRPS Compared to CRPS in the Headand Neck
No standardized criteria for the diagnosis of CRPSare in common use. Bonica30 introduced the idea
of stages (grade 1, grade 2, and grade 3) related to
the severity of the symptoms (severe, moderate,
and mild, respectively). An RSD score system for
diagnosis of CRPS was proposed by Gibbons and
Wilson64 based on the presence of the following in
the patient’s clinical presentation: allodynia/hyper-
pathia, burning pain, edema, color/hair growth
changes, sweating changes, temperature changes,
radiographic changes, quantitative measurementsof vasomotor/sudomotor disturbances, bone scanwith RSD, and response to sympathetic block. Thepatient was assigned 1 point for positive, a halfpoint for equivocal, and no points if the criterionwas negative or not mentioned. The condition wasscored as follows: total RSD score less than 3 =patient considered not to have RSD; total RSD
the intensity is disproportionate to the inciting
score between 3 and 4.5 = patient may have RSD;
event and decreases when the extremity is elevated.
total RSD score 5 or more = patient probably has
Other abnormal sensations related to pain that
RSD. However, because of the lack of agreement
are found in CRPS patients include mechanical
on the definition and diagnostic criteria for CRPS
and thermal hyperalgesia, hyperesthesia, allodynia,
(causalgia/RSD), in 1993 a special consensus
hyperpathia, and dysesthesia. In addition to these,
workshop of the IASP examined and revised the
signs of inflammation are present together with a
IASP taxonomy for this disorder.7,8 The names
number of typical abnormalities that are probably
CRPS type I (RSD) and CRPS type II (causalgia)
related to autonomic dysfunction. These include
were suggested, and diagnostic criteria were listed
edema, abnormality of sweating (either hypohidro-
(Fig 1). Associated signs and symptoms were also
sis or hyperhidrosis), and skin changes whereby
listed, but not used for the diagnosis of CRPS.7
the skin appears mottled, reddish, bluish, or pale.
These include atrophy of the hair, nails, and other
The skin of the affected side can be either warmer
soft tissues; alterations in hair growth; loss of joint
or colder compared to the other side. There also
mobility; impairment of motor function, including
may be trophic changes such as abnormal nail
weakness, tremor, and dystonia; and the presence
growth, with the nails becoming coarse and rigid;
of sympathetically maintained pain. To differenti-
increased hair growth, where the hair can become
ate between SMP and SIP, a sympatholytic proce-
either thin and sparse or coarse and thick; thin,
dure is used without playing a role in the differen-
glossy skin; and hyperkeratosis. Additional signs
tial diagnosis of CRPS types I or II.
are stiffness in the joints, movement restriction,
The criteria stated for the diagnosis of CRPS
and muscle weakness.9,30 Stiffness of the joints
have yet to be validated in empirical studies. As
might lead to splinting of the affected part to pre-
one step in the validation process, Galer65 pro-
vent further aggravation of the pain and fibrosis
posed that the CRPS criteria should be able to dis-
tinguish CRPS patients from patients with other
Table 1 shows the percentage of the prevalence
neuropathic pain syndromes of distinct and known
of CRPS symptoms based on the values reported
etiology. In his study he compared CRPS patients
by Boas63 and compared to the prevalence of
to patients with painful diabetic neuropathy and
symptoms of CRPS in the head and neck extrapo-
concluded that the IASP diagnostic criteria may
lated from the cases in the literature (see below,
lack specificity, since 37% of diabetic subjects met
and Table 2). It is evident that pain is the main
feature of the disease when it occurs in the face,
A further evaluation of IASP diagnostic criteria
followed by hyperalgesia and/or hyperesthesia.
was performed by Bruehl et al.66 Their survey
The other signs or symptoms are much less fre-
showed that although sensitivity was quite high
quent in comparison to CRPS elsewhere in the
(0.98), specificity was low (0.36); they therefore
proposed modifications to the criteria. Other
REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
COPYRIGHT 2002 BY QUINTESSENCE PUBLISHING CO, INC.PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART OF THI
Criteria for CRPS type I Criteria for CRPS type II (reflex sympathetic dystrophy) (causalgia)
•Condition develops after an initiating noxious event.
•Condition develops after a nerve injury.
•Spontaneous pain or allodynia/hyperalgesia occurs,
•Spontaneous pain or allodynia/hyperalgesia occurs
is not limited to the territory of a single peripheral
and is not necessarily limited to the territory of the
nerve, and is disproportionate to the inciting event.
•There is or has been evidence of edema, skin blood
•There is or has been evidence of edema, skin blood
flow abnormality, or abnormal sudomotor activity in
flow abnormality, or abnormal sudomotor activity in
the region of the pain since the inciting event.
the region of the pain since the inciting event.
•The diagnosis is excluded by the existence of condi-
•The diagnosis is excluded by the existence of condi-
tions that otherwise would account for the degree of
tions that otherwise would account for the degree of
Fig 1 CRPS criteria.7,8
changes were also suggested by Harden et al67:
reflex loops. It is a valuable test, but because it
separate the signs and symptoms into 2 different
examines axon reflex, it cannot be used to test
categories, and require the presence of signs and
symptoms in each of 4 categories (sensory, vaso-
• Bone scintigraphy. Bone scintigraphy gives
motor, sudomotor/edema, and motor/trophic).
information about changes occurring in bonevascularity. It tells only of significant changesthat occur during the subacute period.71,72 A 3-
phase bone scan can give a more discriminativescintigraphic description of the disease.73,74
The diagnosis of CRPS is mainly clinical; on the
• Plain radiographs. Radiographic images can
other hand, the following objective diagnostic pro-
show the status of mineralization in the bones of
cedures have been reported in the literature to con-
the affected side in comparison to the contralat-
firm the diagnostic impression of autonomic, sen-
eral side. Positive findings can be observed in
chronic stages but can also be related to disuse
• Quantitative sensory tests. These tests measure
subjective responses to superficial stimulation
• Sympathetic nerve blocks. This method is a diag-
and provide information regarding peripheral
nostic and therapeutic treatment at the level of
nerve function of myelinated and unmyelinated
the sympathetic ganglia, where a local anesthetic,
afferent fibers responding to tactile, pressure,
intravenous phentolamine, or regional intra-
venous blocks with an adrenergic blocking agent
• Laser doppler flowmetry. This procedure mea-
can be used. The side effects of such invasive pro-
sures the skin blood flow in the tested area,
cedures include miosis, ptosis, and enophthalmos
which can be compared to that in the contralat-
(Horner’s syndrome); recurrent laryngeal nerve
injury leading to hoarseness; and occasional
• Infrared thermography. Infrared thermography
shortness of breath (from phrenic nerve block).
records the distribution of skin temperature.
Sympathetic nerve blocks can also result in
Each area of the skin is then compared with the
hemidiaphragm paralysis. Loss of consciousness,
seizures, and severe arterial hypotension mayoccur if the vertebral artery is injected. Air
• Quantitative sudometer axon reflex test. This
test measures evoked sweat response and givesinformation on the function of the sudomotor
REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
COPYRIGHT 2002 BY QUINTESSENCE PUBLISHING CO, INC.PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART OF THI
system aggravates the pain, inhibiting or reducingits tone should provide pain relief. One of the proce-
There is no specific protocol designed for the treat-
dures that can be performed and has given good
ment of either CRPS type I or type II, but several
results in many studies23,42,53,80,88,91–95 is a repeti-
procedures and pharmacologic interventions have
tion of stellate ganglion blocks until the pain is sig-
been tried. Not all treatments are effective in every
nificantly reduced, according to the patient’s satis-
patient; this is the reason why different treatments
faction. Different solutions have been injected, such
are often tried, starting with the least invasive
as bupivacaine,23,53,89,93,96 phenol,91 morphine,42
techniques and evaluating the result and the
alcohol,87 and unspecified local anesthetic.42
patient’s satisfaction with the treatment. The pur-
Another approach is through sympatholytic
pose of the therapy is to relieve pain and improve
drugs that act on norepinephrine receptors.
function. For pain control, some efficacy and very
Guanethidine has been suggested,13 because it
few and mild side effects have been seen with the
decreases the presynaptic release of norepinephrine
use of transcutaneous electrical nerve stimula-
at the neuron site,97–99 as has phentolamine,13,15
tion9,77 or peripheral nerve stimulation. The use of
which reduces the action of norepinephrine on the
biofeedback has also been suggested to enable the
receptors by blocking both ß and ß receptors
patient to alter sympathetic activity and increase
peripherally.100–103 Probably the most widely used
or decrease blood flow to the affected area.78
medication in this family is clonidine9,10,13,15,104,105
Many medications have been tried from among
because of its milder side effects. It acts centrally
those used in the treatment of other types of neu-
on presynaptic ß receptors as an agonist, and in
ropathic pain. Nonsteroidal anti-inflammatory
doing so it decreases the release of norepinephrine
drugs have been helpful in some cases,9,10,15,79 as
from the presynaptic neuron.98,99,101,102
well as corticosteroids,9,10,15,80,81 to address the
A more aggressive intervention, surgical cervical
peripheral component of the pain; opioids have
sympathectomy, has been described, with positive
also been useful in some patients.9,10,13,82
Membrane stabilizers acting on sodium channels,
All the treatments designed to address the pain
such as phenytoin, carbamazepine,10,13,15,83 mex-
are meant to be accompanied by physical therapy
iletine,9,10,13,15,84 and local anesthetics,9,10,13,15,85
to restore the patient’s capacity to function.9,78,79
have been suggested with the purpose of reducing
The exercises to be performed need to be suited to
the normal and ectopic firing of neurons. Good
the patient’s state of the disease, starting with
results have been reported with tricyclic antide-
immobilization during the acute phase, proceeding
pressants, with amitriptyline being the most fre-
to passive and active isometric exercises with
quently used.9,10,82 Other kinds of antidepressants
stress-loading activities (scrubbing, walking, carry-
do not have the same effect on neuropathic
ing weights), and finishing with isotonic train-
pain,10,86 but venlafaxine, a serotonin and nore-
ing.9,10 In the early stages, a process of gentle con-
pinephrine reuptake inhibitor, has been sug-
trolled stimulation via heat, massage, pressure,
gested.13,65 Gabapentin is a relatively new drug
cold, vibration, and movement can help restore
that is being used in trigeminal neuralgia and has
been suggested for the treatment of other kinds of
Appropriate counseling to manage psychologic
neuropathic pain9,10,13; it has also been used for
issues such as depression, anxiety, anger, and per-
the treatment of CRPS with encouraging results.87
sonality disorders is indicated in some cases. Also,
The use of topical capsaicin has been suggested to
the cognitive-behavioral approach is often helpful
reduce peripheral inputs,10,13 and another medica-
to overcome pain avoidance, overprotection,
tion, N-acetylcysteine, has also been tried.88
Other methods that have been used are adminis-
tration of scavengers of oxygen free radicals,88,89deep brain stimulation in the sensory thalamus and
the medial lemniscus,9,77 and epidural spinal cord
stimulation.9,77,90 With this last technique it was
A MEDLINE search for the cases of CRPS in the
reported that CRPS patients had more satisfactory
head and neck reported in the literature was per-
results than other chronic pain patients.90
formed. An account of the patients who did meet
If there is evidence of a sympathetic component of
most of the IASP criteria, according to what was
the pain (ie, SMP), other techniques or medications
reported by the authors23,42,53,81,88,91,93,104,106,107 in
can be helpful. Since the activity of the sympathetic
the original articles, is summarized in Table 2.
REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
RIGHT 2002 BY QUINTESSENCE PUBLISHING CO, INC.PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART OF THIS AR
Summary of CRPS Cases in the Head and Neck
movements distribution(eating, much talking)
mandible; constant“pinching” sensationover the left eyebrowand mandible; photo-phobia left eye
REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
TO PERSONAL USE ONLY.NO PART OF THIS ARTICLE MAY BE
COPYRIGHT 2002 BY QUINTESSENCE PUBLISHING CO, INC.PRINTING OF THIS DOCUMENT IS RESTRICTED Table 2 (continued) Summary of CRPS Cases in the Head and Neck
frontal sinus, followedby postoperativeinfection and anotheroperation to reopenthe sinus
SG = stellate ganglion; MVA = motor vehicle accident; LA = local anesthetic.
As with CRPS in other parts of the body, the
Rarely, diagnostic tests other than sympathetic
signs and symptoms of CRPS in the face always
blocks were performed (Table 2). This confirms
start after a traumatic event, eg, a penetrating
that the diagnosis of CRPS is basically clinical;
lesion on the skin of the face, tooth extraction, or
diagnostic procedures are used to confirm the
surgical trauma to the craniofacial region (Table
diagnosis but are meaningless by themselves.
2). Pain is always present, almost always of burn-
The treatment performed in almost all the
ing quality, and associated with hyperalgesia or
patients (Table 2) was a series of injections in the
hyperesthesia. Less frequently, skin color and tem-
stellate ganglion of local anesthetics—bupivacaine
perature changes, numbness, and hypoesthesia
alone in most of the subjects, plus morphine or
were reported; rarely, edema and trophic changes
phenol in 1 patient each. The blocks were always
involving the skin and hair were described, making
preceded by a diagnostic trial to determine
the diagnosis of CRPS uncertain according to the
whether or not the sympathetic system had a role
in maintaining the pain. The outcome was very
REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
COPYRIGHT 2002 BY QUINTESSENCE PUBLISHING CO, INC.PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART OF THI
successful in all the patients and ranged from 50%
repeated several times until the patient achieves a
to 100% pain relief. In 1 patient, the sympathetic
satisfactory result. Because relief from the pain and
blocks were associated with administration of 30
the other symptoms occurs after this treatment
procedure, we do not find the recommendation of
cervical sympathectomy justified, even though the
reported as alternatives to stellate ganglion block-
reported results have been excellent.
ade. In 1 patient, intravenous guanethidine was
Since only a few of the procedures suggested for
used in conjunction with physical therapy and pro-
the treatment of CRPS have been performed for
duced partial improvement; in another, 0.1 mg
the treatment of CRPS in the head and neck, it is
clonidine was administered twice a day and
impossible for us to conclude that the same
resulted in substantial improvement of the pain.
approach works equally well in both situations.
Two patients were treated with a more invasive
However, a series of sympathetic blocks with local
procedure, cervical sympathectomy. The outcome
anesthetics seems to be an effective procedure,
was the complete resolution of symptoms.
regardless of the location of the symptoms.
Pharmacologic treatment with methylprednisolone
The lack of controlled trials for the treatment of
was used in a patient who refused the sympathetic
the cases reported does not allow us to reach
block, and the result was excellent. N-acetylcysteine
definitive conclusions. Double-blind and con-
600 mg 3 times a day was tried in another subject
trolled studies are necessary to evaluate the out-
with moderately good results: the inflammation
come of the treatments, but unfortunately the very
decreased, but the pain subsided only partially.
small number of cases presented with this syn-
It is debatable whether the comparison between
cases of CRPS in the head and neck with CRPS inother parts of the body may be valid because ofthe small number of reported cases of CRPS in the
head and neck (Table 1). In addition, the casedescriptions in the articles are brief, and authors
The authors would like to acknowledge the guidance of Dr
may not have mentioned all of the symptoms.
George Maloney, Dr Albert Forgione, and Dr Ronald Kulichfor their comments and suggestions when preparing this article.
In light of what the literature reviewed, CRPS in
1. Mitchell S, Morehouse C, Keane W. Gunshot Wounds
the head and neck seems to be a very rare condi-
and Other Injuries of the Nerves. Philadelphia: Lippincott,
tion, with only 13 cases clearly described since
1947. It may be that CRPS might be an atypical
2. Mitchell S. Injuries of Nerves and Their Consequences, ed
presentation of a more common disorder such as
3. Elfenbaum A. Causalgia in dentistry: An abandoned pain
myofascial pain that not infrequently presents with
syndrome. Oral Surg Oral Med Oral Pathol 1954;7:
different types of pain and abnormalities involving
the autonomic system. Also, misinterpretation of
4. Leriche R. De la causalgie, envisage comme une nevrite
patients’ symptoms might have a role, together
due sympathique et desson traitement par la denudation et
with the inflammation of the soft tissues that can
l’excision des plexus nerveux periartieriels. Presse Med1916;24:178–180.
5. Leriche R. La Chirurgie del la douleur. Paris: Massont,
Another possibility is that the orofacial region
may respond differently to trauma than would
6. Evans J. Reflex sympathetic dystrophy. Surg Clin North
other locations, and this has been observed in ani-
mals.108,109 Another possibility is that CRPS does
7. Merskey H, Bogduk N. Classification of Chronic Pain:
Descriptions of Chronic Pain Syndromes and Definitions
occur, but it is very rare in the head and neck
of Pain Terms, ed 2. Seattle: IASP Press, 1994.
8. Stanton-Hicks M, Janig W, Hassenbusch S, Haddox JD,
Another important feature we found is that,
Boas R, Wilson P. Reflex sympathetic dystrophy:
although involvement of the sympathetic system is
Changing concepts and taxonomy [see comments]. Pain
not required for the diagnosis of CRPS, the sympa-
9. Wasner G, Backonja MM, Baron R. Traumatic neuralgias:
thetic system has a major role in the perpetuation
Complex regional pain syndromes (reflex sympathetic dys-
of pain. In fact, sympatholytic procedures seem to
trophy and causalgia): Clinical characteristics, pathophysi-
be the treatment of choice, starting with a stellate
ological mechanisms and therapy. Neurol Clin
ganglion block (with local anesthetic) that is
REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
COPYRIGHT 2002 BY QUINTESSENCE PUBLISHING CO, INC.PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART OF THI
10. Stanton-Hicks M, Baron R, Boas R, et al. Complex
31. Woda A, Pionchon P. Topical review: A unified concept of
regional pain syndromes: Guidelines for therapy [see com-
idiopathic orofacial pain: Pathophysiologic features. J
ments]. Clin J Pain 1998;14(2):155–166.
11. Okeson J. Neuropathic pains. In: Okeson J (ed). Bell’s
32. Woolf CJ, Shortland P, Coggeshall RE. Peripheral nerve
Orofacial Pains, ed 5. Chicago: Quintessence, 1995:
injury triggers central sprouting of myelinated afferents.
12. Gregg JM. Studies of traumatic neuralgias in the maxillo-
33. Miki K, Fukuoka T, Tokunaga A, Noguchi K. Calcitonin
facial region: Surgical pathology and neural mechanisms. J
gene-related peptide increase in the rat spinal dorsal horn
Oral Maxillofac Surg 1990;48(3):228–237, discussion
and dorsal column nucleus following peripheral nerve
injury: Up-regulation in a subpopulation of primary affer-
13. Woolf C, Mannion R. Neuropathic pain: Etiology, symp-
ent sensory neurons. Neuroscience 1998;82(4):
toms, mechanisms, and management. N Engl Pain Assoc
34. Neumann S, Doubell TP, Leslie T, Woolf CJ.
14. Ochoa J, Torebjork HE, Culp WJ, Schady W. Abnormal
Inflammatory pain hypersensitivity mediated by pheno-
spontaneous activity in single sensory nerve fibers in
typic switch in myelinated primary sensory neurons.
humans. Muscle Nerve 1982;5(9S):S74–S77.
15. Devor M. The pathophysiology of damaged peripheral
35. Cho HJ, Kim DS, Lee NH, et al. Changes in the alpha 2-
nerves. In: Wall P, Melzack R (eds). Textbook of Pain, ed
adrenergic receptor subtypes gene expression in rat dorsal
3. New York: Churchill Livingstone, 1994:79–100.
root ganglion in an experimental model of neuropathic
16. Seltzer Z, Devor M. Ephaptic transmission in chronically
pain. Neuroreport 1997;8(14):3119–3122.
damaged peripheral nerves. Neurology 1979;29(7):
36. Gonzales R, Goldyne ME, Taiwo YO, Levine JD.
Production of hyperalgesic prostaglandins by sympathetic
17. Granit R, Leksell L, Skoglund C. Fibre interaction in
postganglionic neurons. J Neurochem 1989;53(5):
injured or compressed region of nerve. Brain 1944;
37. Mackinnon S, Dellon A. Painful sequelae in peripheral
18. Doupe T, Cullen C, Chance G. Post-traumatic pain in the
nerve injury. In: Mackinnon S, Dellon A (eds). Surgery of
causalgic syndrome. J Neurol Neurosurg Psychiatry
the Peripheral Nerve. New York: Thieme Medical
19. Nathan P. On the pathogenesis of causalgia in peripheral
38. Wall P, Gutnick M. Ongoing activity in peripheral nerves:
nerve injuries. Brain 1947;70:145–170.
The physiology and pharmacology of impulses originating
20. McLachlan EM, Janig W, Devor M, Michaelis M.
from a neuroma. Exp Neurol 1974;43(3):580–593.
Peripheral nerve injury triggers noradrenergic sprouting
39. Smith KJ, McDonald WI. Spontaneous and mechanically
within dorsal root ganglia. Nature 1993;363(6429):
evoked activity due to central demyelinating lesion.
21. Jänig W, Levine JD, Michaelis M. Interactions of sympa-
40. Calvin WH, Devor M, Howe JF. Can neuralgias arise
thetic and primary afferent neurons following nerve injury
from minor demyelination? Spontaneous firing,
and tissue trauma. Prog Brain Res 1996;113:161–184.
mechanosensitivity, and afterdischarge from conducting
22. Baron R, Levine JD, Fields HL. Causalgia and reflex sym-
axons. Exp Neurol 1982;75(3):755–763.
pathetic dystrophy: Does the sympathetic nervous system
41. Baker M, Bostock H. Ectopic activity in demyelinated
contribute to the generation of pain? Muscle Nerve
spinal root axons of the rat. J Physiol 1992;451:539–552.
42. Jaeger B, Singer E, Kroening R. Reflex sympathetic dystro-
23. Hanowell ST, Kennedy SF. Phantom tongue pain and
phy of the face. Report of two cases and a review of the
causalgia: Case presentation and treatment. Anesth Analg
literature. Arch Neurol 1986;43(7):693–695.
43. Johnson LR, Westrum LE, Canfield RC. Ultrastructural
24. Melzack R. Phantom limb pain: Implications for treat-
study of transganglionic degeneration following dental
ment of pathologic pain. Anesthesiology 1971;35(4):
lesions. Exp Brain Res 1983;52(2):226–234.
44. Gobel S. An electron microscopic analysis of the trans-
25. Livingston W. Pain Mechanisms. New York: Plenum
synaptic effects of peripheral nerve injury subsequent to
tooth pulp extirpations on neurons in laminae I and II of
26. Gerad R. The physiology of pain—Abnormal neuron
the medullary dorsal horn. J Neurosci 1984;4(9):
states in causalgia and related phenomena. Anesthesiology
45. Gregg JM. Posttraumatic pain: Experimental trigeminal
27. Livingston W. Pain Mechanisms; A Physiologic
neuropathy. J Oral Surg 1971;29(4):260–267.
Interpretation of Causalgia and Its Related States. New
46. Aldskogius H, Arvidsson J. Nerve cell degeneration and
death in the trigeminal ganglion of the adult rat following
28. Anderson LS, Black RG, Abraham J, Ward AA Jr.
peripheral nerve transection. J Neurocytol 1978;7(2):
Neuronal hyperactivity in experimental trigeminal deaf-
ferentation. J Neurosurg 1971;35(4):444–452.
47. Sessle BJ. The neural basis of temporomandibular joint
29. Westrum LE, Black RG. Changes in the synapses of the
and masticatory muscle pain. J Orofac Pain 1999;13(4):
spinal trigeminal nucleus after ipsilateral rhizotomy. Brain
48. Sessle BJ. Acute and chronic craniofacial pain: Brainstem
30. Bonica JJ. Causalgia and other reflex sympathetic dystro-
mechanisms of nociceptive transmission and neuroplastic-
phies. In: Bonica JJ (ed). Management of Pain, ed 2.
ity, and their clinical correlates. Crit Rev Oral Biol Med
Philadelphia: Lea & Febiger, 1990:220–243.
REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
COPYRIGHT 2002 BY QUINTESSENCE PUBLISHING CO, INC.PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART OF THI
49. Hu JW, Sessle BJ. Effects of tooth pulp deafferentation on
67. Harden RN, Bruehl S, Galer BS, et al. Complex regional
nociceptive and nonnociceptive neurons of the feline
pain syndrome: Are the IASP diagnostic criteria valid and
trigeminal subnucleus caudalis (medullary dorsal horn). J
sufficiently comprehensive? Pain 1999;83(2):211–219.
Neurophysiol 1989;61(6):1197–1206.
68. Baron R, Maier C. Reflex sympathetic dystrophy: Skin
50. Wall PD, Devor M. Sensory afferent impulses originate
blood flow, sympathetic vasoconstrictor reflexes and pain
from dorsal root ganglia as well as from the periphery in
before and after surgical sympathectomy. Pain 1996;67(2-
normal and nerve injured rats. Pain 1983;17(4):321–339.
51. Burchiel KJ. Spontaneous impulse generation in normal
69. Low PA, Amadio PC, Wilson PR, McManis PG, Willner
and denervated dorsal root ganglia: Sensitivity to alpha-
CL. Laboratory findings in reflex sympathetic dystrophy:
adrenergic stimulation and hypoxia. Exp Neurol
A preliminary report. Clin J Pain 1994;10(3):235–239.
70. Chelimsky TC, Low PA, Naessens JM, Wilson PR,
52. DeSantis M, Duckworth JW. Properties of primary affer-
Amadio PC, O’Brien PC. Value of autonomic testing in
ent neurons from muscle which are spontaneously active
reflex sympathetic dystrophy [see comments]. Mayo Clin
after a lesion of their peripheral processes. Exp Neurol
71. Genant HK, Kozin F, Bekerman C, McCarty DJ, Sims J.
53. Khoury R, Kennedy SF, Macnamara TE. Facial causalgia:
The reflex sympathetic dystrophy syndrome. A compre-
Report of case. J Oral Surg 1980;38(10):782–783.
hensive analysis using fine-detail radiography, photon
54. Watkins LR, Wiertelak EP, Goehler LE, Smith KP, Martin
absorptiometry, and bone and joint scintigraphy.
D, Maier SF. Characterization of cytokine-induced hyper-
algesia. Brain Res 1994;654(1):15–26.
72. Kozin F, Genant HK, Bekerman C, McCarty DJ. The
55. Watkins LR, Maier SF, Goehler LE. Immune activation:
reflex sympathetic dystrophy syndrome. II.
The role of pro-inflammatory cytokines in inflammation,
Roentgenographic and scintigraphic evidence of bilateral-
illness responses and pathological pain states. Pain
ity and of periarticular accentuation. Am J Med
56. Watkins LR, Maier SF. The pain of being sick:
73. Holder LE, Mackinnon SE. Reflex sympathetic dystrophy
Implications of immune-to-brain communication for
in the hands: Clinical and scintigraphic criteria. Radiology
understanding pain. Ann Rev Psychol 2000;51:29–57.
57. DeLeo JA, Colburn RW, Nichols M, Malhotra A.
74. Kozin F, Soin JS, Ryan LM, Carrera GF, Wortmann RL.
Interleukin-6-mediated hyperalgesia/allodynia and
Bone scintigraphy in the reflex sympathetic dystrophy syn-
increased spinal IL-6 expression in a rat mononeuropathy
drome. Radiology 1981;138(2):437–443.
model. J Interferon Cytokine Res 1996;16(9):695–700.
75. Wilson PR, Low PA, Bedder MD, Covington EC, Rauck
58. DeLeo JA, Colburn RW, Rickman AJ. Cytokine and
RL. Diagnostic algorithm for complex regional pain syn-
growth factor immunohistochemical spinal profiles in two
drome. In: Jänig W, Stanton-Hicks M (eds). Progress in
animal models of mononeuropathy. Brain Res
Pain Research and Management. Vol 6: Reflex sympa-
thetic dystrophy: A reappraisal. Seattle: IASP Press,
59. DeLeo JA, Rutkowski MD, Stalder AK, Campbell IL.
Transgenic expression of TNF by astrocytes increases
76. Stanton-Hicks M, Raj PP, Racz GB. Use of regional anes-
mechanical allodynia in a mouse neuropathy model.
thetic for diagnosis of reflex sympathetic dystrophy and
sympathetically maintained pain: A critical evaluation. In:
60. Merrill RL. Orofacial pain mechanisms and their clinical
Jänig W, Stanton-Hicks M (eds).Progress in Pain Research
application. Dent Clin North Am 1997;41(2):167–188.
and Management. Vol 6: Reflex sympathetic dystrophy: A
61. Blumberg H, Jänig W. Clinical manifestation of reflex
reappraisal. Seattle: IASP Press, 1996:217–237.
sympathetic dystrophy and sympathetically maintained
77. Hassenbusch SJ, Stanton-Hicks M, Schoppa D, Walsh JG,
pain. In: Wall PD, Melzack R (eds). Textbook of Pain, ed
Covington EC. Long-term results of peripheral nerve stim-
3. Edinburgh: Churchill Livingstone, 1994:685–697.
ulation for reflex sympathetic dystrophy. J Neurosurg
62. Oyen WJ, Arntz IE, Claessens RM, Van der Meer JW,
Corstens FH, Goris RJ. Reflex sympathetic dystrophy of
78. Headley B. Historical perspective of causalgia.
the hand: An excessive inflammatory response? Pain
Management of sympathetically maintained pain. Phys
63. Boas RA. Complex regional pain syndromes: Symptoms,
79. Kiroglu MM, Sarpel T, Ozberk P, Soylu L, Cetik F,
signs, and differential diagnosis. In: Jänig W, Stanton-
Aydogan LB. Reflex sympathetic dystrophy following
Hicks M (eds). Progress in Pain Research and
neck dissections. Am J Otolaryngol 1997;18(2):103–106.
Management. Vol 6: Reflex sympathetic dystrophy: A
80. Poplawski ZJ, Wiley AM, Murray JF. Post-traumatic dys-
reappraisal. Seattle: IASP Press, 1996:79–92.
trophy of the extremities. J Bone Joint Surg [Am]
64. Gibbons JJ, Wilson PR. RSD score: Criteria for the diag-
nosis of reflex sympathetic dystrophy and causalgia [see
81. Figuerola M, Bruera O, and Leston J. Reflex sympathetic
comments]. Clin J Pain 1992;8(3):260–263.
dystrophy of the face: An unusual cause of facial pain.
65. Galer BS. Painful polyneuropathy. Neurol Clin
82. Nesathurai S, Harvey DT, Schatz SW. Gustatory facial
66. Bruehl S, Harden RN, Galer BS, et al. External validation
sweating subsequent to upper thoracic sympathectomy.
of IASP diagnostic criteria for Complex Regional Pain
Arch Phys Med Rehabil 1995;76(1):104–107.
Syndrome and proposed research diagnostic criteria.
83. Swerdlow M. Anticonvulsant drugs and chronic pain. Clin
International Association for the Study of Pain. Pain
REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
COPYRIGHT 2002 BY QUINTESSENCE PUBLISHING CO, INC.PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.NO PART OF THI
84. Chabal C, Jacobson L, Mariano A, Chaney E, Britell CW.
97. Gerber J, Nies A. Antihypertensive agents and the drug
The use of oral mexiletine for the treatment of pain after
therapy for hypertension. In: Goodman GA, Rall T, Nies
peripheral nerve injury. Anesthesiology 1992;76(4):
A, Taylor P (eds). Goodman and Gilman’s The
Pharmacological Basis of Therapeutics, ed 8. New York:
85. Swerdlow M. Review: The use of local anaesthetic for
relief of chronic pain. Pain Clin 1988;2:3–6.
98. Benowitz N. Antihypertensive agents. In: Katzung B (ed).
86. Max MB, Lynch SA, Muir J, Shoaf SE, Smoller B, Dubner
Basic and Clinical Pharmacology, ed 6. Norwalk, CT:
R. Effects of desipramine, amitriptyline, and fluoxetine on
Appleton & Lange, 1994:155–180.
pain in diabetic neuropathy [see comments]. N Engl J Med
99. Jacob LS. Cardiovascular agents. In: Williams W (ed).
Pharmacology. Malvern: Harwal, 1992:95–132.
87. Mellick GA, Mellicy LB, Mellick LB. Gabapentin in the
100. Hoffman B. Adrenoceptor against drugs. In: Katzung B
management of reflex sympathetic dystrophy [letter]. J
(ed). Basic and Clinical Pharmacology, ed 6. Norwalk,
Pain Symptom Manage 1995;10(4):265–266.
CT: Appleton & Lange, 1994:138–154.
88. Veldman PH, Jacobs PB. Reflex sympathetic dystrophy of
101. Hoffman B, Lefkowitz R. Catecholamines and sympath-
the head: Case report and discussion of diagnostic criteria.
omimetic drugs. In: Goodman GA, Gilman A, Rall TW,
Nies AS, Taylor P (eds). Goodman and Gilman’s The
89. Goris RJ. Treatment of reflex sympathetic dystrophy with
Pharmacological Basis of Therapeutics, ed 8. New York:
hydroxyl radical scavengers. Unfallchirurg 1985;88(7):
102. Hoffman B, Lefkowitz R. Adrenergic receptor antagonists.
90. Shimoji K, Hokari T, Kano T, et al. Management of
In: Goodman GA, Gilman A, Rall TW, Nies AS, Taylor P
intractable pain with percutaneous epidural spinal cord
(eds). Goodman and Gilman’s The Pharmacological Basis
stimulation: Differences in pain-relieving effects among
of Therapeutics, ed 8. New York: Pergamon Press,
diseases and sites of pain. Anesth Analg 1993;77(1):
103. Jacob L. Drug affecting peripheral neurohumoral trans-
91. Arden RL, Bahu SJ, Zuazu MA, Berguer R. Reflex sympa-
mission. In: Williams W (ed). Pharmacology, ed 3.
thetic dystrophy of the face: Current treatment recommen-
dations. Laryngoscope 1998;108(3):437–442.
104. Saxen MA, Campbell RL. An unusual case of sympatheti-
92. Kozin F, McCarty DJ, Sims J, Genant H. The reflex sym-
cally maintained facial pain complicated by telangiectasia.
pathetic dystrophy syndrome. I. Clinical and histologic
Oral Surg Oral Med Oral Pathol Oral Radiol Endod
studies: Evidence for bilaterality, response to cortico-
steroids and articular involvement. Am J Med
105. Davis KD, Treede RD, Raja SN, Meyer RA, Campbell JN.
Topical application of clonidine relieves hyperalgesia in
93. Teeple E, Ferrer EB, Ghia JN, Pallares V. Pourfour Du
patients with sympathetically maintained pain [see com-
Petit syndrome—Hypersympathetic dysfunctional state
following a direct non-penetrating injury to the cervical
106. Bingham JA. Causalgia of the face: Two cases successfully
sympathetic chain and brachial plexus. Anesthesiology
treated by sympathectomy. Br Med J 1947;1(June):
94. Driessen JJ, van der Werken C, Nicolai JP, Crul JF.
107. Behrman S. Facial neuralgias. Br Dent J 1949;86:197–203.
Clinical effects of regional intravenous guanethidine
108. Bongenhielm U, Boissonade FM, Westermark A,
(Ismelin) in reflex sympathetic dystrophy. Acta
Robinson PP, Fried K. Sympathetic nerve sprouting fails
Anaesthesiol Scand 1983;27(6):505–509.
to occur in the trigeminal ganglion after peripheral nerve
95. Wang JK, Johnson KA, Ilstrup DM. Sympathetic blocks
injury in the rat. Pain 1999;82(3):283–288.
for reflex sympathetic dystrophy. Pain 1985;23(1):13–17.
109. Benoliel R, Eliav E, Tal M. No sympathetic sprouting in
96. Lynch ME, Elgeneidy AK. The role of sympathetic activity
rat trigeminal ganglion following painful and non-painful
in neuropathic orofacial pain. J Orofac Pain 1996;10(4):
infraorbital nerve neuropathy. Neurosci Lett
DELAWARE HEALTH AND SOCIAL SERVICES _______________________________________________________________ Division of Public Health _______________________________________________________________ Delaware AIDS Drug Assistance Program (ADAP) Formulary as of September 27, 2011 Antiretrovirals Abacavir (Ziagen) Abacavir/lamivudine (Epzicom) Amprenavir (Agenerase) Atazanavir (Reyataz) C
Impact factor totale: 135.50 H-Index: 16 Citazioni totali (JCR 11/03/2011): 1093 Guerrisi M , Vannucci I, Toschi N Differential response of peripheral arterial elasticity indices to a vasoconstrictive stimulus PHYSIOLOGICAL MEASUREMENT 2009, Vol 30, Iss 1, pp 81-100 Guerrisi M , Toschi N Ventricular interaction and cardiac pathologies in a thick shell model of cardiac chamber