Early electrodiagnostic findings in Guillain-Barré syndrome

CONTEXT

Guillain-Barré syndrome (GBS) is the foremost cause of acute, generalized, peripheral neuropathic weakness. Although nerve conduction studies are a diagnostic aid, the characteristic electrical changes may not evolve for several weeks. Early diagnosis of GBS is important, however, because early treatment has been shown to improve outcome.

OBJECTIVES

To describe the electrodiagnostic abnormalities detectable in the first week of GBS, to determine if there are early patterns suggestive of GBS, and to identify the percentage of patients whose condition can be diagnosed with reasonable certainty in the first week.

DESIGN AND SETTING

We retrospectively reviewed the medical records of all patients admitted to the Cleveland Clinic Foundation, Cleveland, Ohio, having the discharge diagnosis GBS during the past 16 years. Patients who underwent nerve conduction studies within 7 days of muscle weakness were selected for this study.

RESULTS

The H reflex was absent in 30 (97%) of 31 patients. Nineteen patients (61%) had low-amplitude or absent sensory nerve action potential (SNAP) in the upper extremity. Fifteen patients (48%) overall, including 21 (67%) of the 31 patients, including 14 (67%) of the 21 patients younger than 60 years, had an abnormal upper extremity SNAP combined with a normal sural SNAP. Other findings included an abnormal F wave (25 patients [84%]), reduced compound muscle action potential amplitude (22 patients [71%]), prolonged distal latency (20 patients [65%]), temporal dispersion (18 patients [58%]), slowed motor conduction velocity (16 patients [52%]), and motor conduction block (4 patients [13%]). Definite diagnosis was possible in 17 patients (55%), but not commonly until the fifth day.

CONCLUSIONS

The H reflex is the most sensitive test for early GBS. Upper extremity SNAPs are also frequently abnormal in early GBS. Absent H response, abnormal F wave, and abnormal upper extremity SNAP combined with a normal sural SNAP are characteristic of early GBS. If multiple nerves are tested, definite diagnosis is possible in half the patients, but not until the fifth day after the onset of symptoms.

Peripheral nerve injuries in athletes: a case series of over 200 injuries

We retrospectively reviewed electrodiagnostic (EDX) studies performed on 346 athletes with sports injuries who were referred to our EDX laboratory from 1974 to 1997. These injuries included 216 nerve root, plexus, or peripheral nerve injuries sustained by 180 of the athletes. Eighty-six percent of the injuries were to the upper extremity. Athletes with nerve fiber injuries participated in 27 different sports, but over one third of injuries were sustained playing football. The most common symptomatic upper extremity injury was the "burner" (N=40). Forty-three athletes had median neuropathies, many of which were asymptomatic cases of carpal tunnel syndrome. Cervical radiculopathies (N=19) and axillary (N=22), ulnar (N=19), and suprascapular (N=14) mononeuropathies were also prevalent. The most common lower extremity injuries were peroneal neuropathies (N=17) and lumbosacral radiculopathies (N=7). This is the largest reported series of sports-related nerve injuries. The mechanisms of the most common nerve injuries are discussed.

Thoracic outlet syndromes

The term thoracic outlet syndromes, is a group designation for several distinct disorders (one of questionable validity) involving various components of the brachial plexus, the blood vessels, or both, at various points between the base of the neck and the axilla. Four of the five subgroups (true neurologic TOS, arterial vascular TOS, venous vascular TOS, and traumatic neurovascular TOS) are universally recognized to be rare lesions, with characteristic clinical and laboratory presentations; and none is particularly controversial. In contrast, disputed neurologic TOS is highly controversial. This article limits discussion to the three subgroups of TOS in which neurologic symptoms are caused, or reputedly are caused, by compromise of the brachial plexus fibers.

AAEM minimonograph 32: the electrodiagnostic examination in patients with radiculopathies. American Association of Electrodiagnostic Medicine

The anatomy and pathophysiology of radiculopathies are reviewed, and the electrodiagnostic approaches used in evaluating patients with suspected root lesions are discussed. Such electrophysiologic procedures include motor and sensory nerve conduction studies, late-response studies, somatosensory and motor evoked potentials, nerve root stimulation, and needle electromyography. The value and limitations of these different procedures are considered. At the present time, needle electromyography is the single most useful approach. The findings in patients with radiculopathies at different levels are summarized.

AAEM minimonograph 32: the electrodiagnostic examination in patients with radiculopathies. American Association of Electrodiagnostic Medicine

The anatomy and pathophysiology of radiculopathies are reviewed, and the electrodiagnostic approaches used in evaluating patients with suspected root lesions are discussed. Such electrophysiologic procedures include motor and sensory nerve conduction studies, late-response studies, somatosensory and motor evoked potentials, nerve root stimulation, and needle electromyography. The value and limitations of these different procedures are considered. At the present time, needle electromyography is the single most useful approach. The findings in patients with radiculopathies at different levels are summarized.

Clinical neurophysiology in the diagnosis of amyotrophic lateral sclerosis: the Lambert and the El Escorial criteria

For many years, the only published criteria for the electrodiagnostic (EDX) recognition of amyotrophic lateral sclerosis (ALS) were those formulated by Lambert (1957; 1969). In 1990, different EDX guidelines were incorporated in the all-inclusive diagnostic criteria formulated by a subcommittee on ALS of the World Federation of Neurology, which met in El Escorial, Spain. Unfortunately, particularly in regard to the EDX requirements, the 'El Escorial criteria' have several flaws which compromise their usefulness. These include: (1) they ignore the fact that whenever upper and lower motor neuron disorders co-exist, as they characteristically do with ALS, the motor unit potential firing pattern is controlled by the upper motor neuron lesion; (2) they markedly devalue the usefulness of detecting fasciculations and, through presumably typographical error, state that the 'absence' rather than the 'presence' of fasciculations supports the diagnosis of ALS; this view is in direct conflict with the opinions expressed by most electromyographers; (3) they contain a statement regarding how the diagnosis of ALS is confirmed by the EDX studies which is confusing and, for two of the body regions (bulbar; thoracic), unrealistic; (4) finally, many of the EDX features they listed supporting the recognition of possible LMN degeneration appear to be mislabeled, while a few features in the EDX criteria are incorrect.

Sports and peripheral nerve injuries: report of 190 injuries evaluated in a single electromyography laboratory

We retrospectively reviewed electrodiagnostic studies performed on 169 athletes with 190 sports injuries to nerve fibers. Eighty-eight percent of the injuries were to the upper extremity. Athletes participated in 27 sports, but over one third of injuries were sustained playing football. The most common injuries were burners (n = 38) and cervical radiculopathies (n = 18), followed by median (n = 28), axillary (n = 22), ulnar (n = 19), suprascapular (n = 14), and peroneal (n = 11) mononeuropathies. This is the largest reported series of sports-related nerve injuries.

Cervical rib and median sternotomy-related brachial plexopathies: a reassessment

OBJECTIVE

The objective of this study was to identify electrodiagnostic and anatomic distinctions between true neurogenic thoracic outlet syndrome and median sternotomy-related brachial plexopathy, in reference to the pattern of abnormality of the medial antebrachial cutaneous sensory nerve conduction study (NCS) response.

BACKGROUND

Neurogenic thoracic outlet syndrome and sternotomy-related brachial plexopathy are both lower trunk brachial plexopathies, but their clinical and electrodiagnostic presentations are distinct. The anatomic differences distinguishing these disorders from each other, and from other lower trunk brachial plexopathies, have not been defined.

METHODS

We compared the medial antebrachial cutaneous sensory nerve action potential amplitude with the median motor, ulnar motor, and ulnar sensory NCS amplitudes in 10 patients with neurogenic thoracic outlet syndrome and in 14 patients with sternotomy-related brachial plexopathy.

RESULTS

In the 10 patients with neurogenic thoracic outlet syndrome, the medial antebrachial cutaneous amplitude was most affected, followed in decreasing order of involvement by the median motor, ulnar sensory, and ulnar motor amplitudes. Conversely, in the 14 patients with sternotomy-related brachial plexopathy, the ulnar sensory and motor amplitudes were the most affected responses. Medial antebrachial cutaneous NCS changes closely paralleled median motor response changes.

CONCLUSIONS

The medial antebrachial cutaneous sensory response is sensitive in the diagnosis of neurogenic thoracic outlet syndrome. Our data suggest that medial antebrachial cutaneous nerve fibers are closely associated anatomically at the T1 root level with median motor fibers innervating the thenar muscles. Neurogenic thoracic outlet syndrome shows predominant damage in the T1 distribution, whereas sternotomy-related brachial plexopathy shows predominant damage in the C8 distribution, suggesting that these lesions are localized at the level of the anterior primary rami of the cervical roots, and not in the lower trunk of the brachial plexus.

Iatrogenic nerve injuries

Iatrogenic nerve injuries are an undesired byproduct of the practice of medicine and have been so since antiquity. The majority of such injuries occur perioperatively, and are, therefore, attributed to surgeons and anesthesiologists. Nonetheless, the members of almost every clinical specialty are at risk to some degree. Iatrogenic nerve injuries can affect almost any portion of the peripheral nervous system, and can result from many different causes. This article reviews many of the more common iatrogenic nerve lesions.

Cervical radiculopathy and coexisting distal entrapment neuropathies: double-crush syndromes?

The double-crush hypothesis (DCH) proposes that a proximal lesion along an axon predisposes it to injury at a more distal site along its course through impaired axoplasmic flow. Although this hypothesis has been accepted, it has anatomic and pathophysiologic restrictions that limit its application as an explanation for coexisting cervical root lesions (CRLs) and carpal tunnel syndrome (CTS) or ulnar neuropathy at the elbow (UN-E). We retrospectively surveyed all electrodiagnostic (EDX) reports of coexisting CTS or UN-E and CRL for anatomic correlation, if any, between the proximal root lesion and the distal entrapment neuropathy. In the period between January 1982 and August 1995 there were 12,736 limbs with CTS or UN-E. In 435 of these limbs (3.4%) there was a coexisting CRL, but only 98 (0.8%) had an association that was anatomically appropriate. Moreover, only 69 (0.5%) of the 98 cases demonstrated axon loss at the distal lesion site on EDX examination. Therefore, cumulatively, only 69 of our 12,736 cases of CTS and UN-E satisfied the pathophysiologic and one of the anatomic requirements of the DCH. Our data thus suggest that a CRL can seldom serve as the proximal lesion with these entrapment neuropathies in the DCH.

The characteristic electrodiagnostic features of Kennedy's disease

To define the electrodiagnostic (EDX) features of Kennedy's disease, their distribution, their clinical correlation, and to determine whether they are unique to this disorder, we retrospectively evaluated the EDX and clinical features of 19 patients with Kennedy's disease and found that: (1) the percentage with sensory nerve action potential abnormalities is high (95%); (2) compound muscle action potential abnormalities are less frequent (37%) and less pronounced; (3) the needle electrode examination is always abnormal (100%), revealing acute and chronic motor axon loss, with the latter predominating; (4) the clinical onset is heterogeneous for both the site of onset (bulbar, upper extremity, lower extremity, combination) and the symptomatology (sensory, motor, sensorimotor); (5) focal onsets were reported in the majority (79%); and (6) there is a strong correlation between the clinical onset (both site and symptomatology) and the maximal EDX abnormalities. Thus, the EDX features of Kennedy's disease are consistent with a slowly progressive and very chronic degeneration of the anterior horn cells and dorsal root ganglia. Although the clinical onsets are heterogenous, the EDX features are homogenous and unique, consisting of a diffuse, very slowly progressive anterior horn cell disorder coupled with a sensory neuropathy/neuronopathy that mimics an acquired process.

Postpartum neuralgic amyotrophy

We report 11 women with at least one episode of neuralgic amyotrophy occurring postpartum. One woman had three episodes-two postpartum and a third occurring after minor foot surgery. Two others had a second episode, one following a first trimester spontaneous abortion and one after a viral syndrome. Pain followed delivery from as little as 1 to 2 hours to up to 2 weeks and usually lasted from a few weeks to several months. Weakness, if delayed, followed onset of pain by 2 or 3 days up to 5 weeks. Four of the episodes were bilateral. Clinical weakness and electrodiagnostic findings varied widely, from involvement of a single peripheral nerve (e.g., long thoracic, anterior interosseous) to multiple bilateral proximal and distal nerves. Functional recovery was excellent (90 to 100%) in 8 of the 10 with adequate follow-up, requiring as little as 2 weeks or up to 3 years. Two women have moderate persisting weakness (both bilateral) at 3 years and 2 years. Five patients went on to subsequent deliveries without recurrence of neuralgic amyotrophy. Only one of the 11 women had a history suggesting familial neuralgic amyotrophy, a disorder generally thought to be associated particularly with postpartum episodes. Although the etiology of postpartum neuralgic amyotrophy remains unknown, an immunologic mechanism is suspected. Focal demyelination may play a role in some, but clearly axonal degeneration is predominant in the majority.

Cervical radiculopathies: comparison of surgical and EMG localization of single-root lesions

To identify the various electrodiagnostic (EDX) patterns of C-5, C-6, C-7, and C-8 cervical radiculopathy, we compared 50 cases of surgically proven solitary-root lesions with their preoperative EDX patterns. We excluded patients with polyradiculopathy, myelopathy, and previous surgery. We classified EDX studies as abnormal only by the needle electrode examination, and only by the demonstration of fibrillation potentials (either the positive sharp wave or the biphasic spike form). Seven patients (14%) had C-5 radiculopathy, nine (18%) had C-6, 28 (56%) C-7, and six (12%) C-8. With C-5, C-7, and C-8 radiculopathies, changes were relatively stereotyped, with involvement of the spinati,deltoid, biceps, and brachioradialis with C-5; the pronator teres, flexor carpi radialis, triceps, and anconeus with C-7; and the first dorsal interosseous, abductor digiti minimi, abductor pollicis brevis, flexor pollicis longus, and extensor indicis proprius with C-8. The root lesion with the most variable presentation was C-6--in half the patients, the findings were similar to C-5 radiculopathies, except that the pronator teres tended to be involved, whereas in the other half, the findings were identical to those with C-7 radiculopathies.

The utility of various sensory nerve conduction responses in assessing brachial plexopathies

To determine which sensory nerve conduction studies (S-NCS) are helpful in detecting supraclavicular axon loss brachial plexopathies, we selected 53 cases (of 417 reviewed) in whom complicating factors were absent and which, by needle electrode examination findings, involved only a single "truncal" element (upper, middle, or lower) of the brachial plexus. Extensive S-NCS included: median, recording thumb (Med-D1), index (Med-D2), and middle fingers (Med-D3); ulnar, recording fifth finger (Uln-D5); dorsal ulnar cutaneous, recording dorsum of the hand (DUC); radial, recording base of thumb; and both medial and lateral antebrachial cutaneous (MABC, LABC), recording forearm. Except for the median sensory fibers, the "cord" elements traversed by the sensory fibers assessed during the S-NCS listed above are anatomically defined (i.e., the sensory fibers enter the brachial plexus at only one cord). In regard to the median sensory fibers, however, there are two possible pathways through the infraclavicular plexus: (1) the lateral cord and/or (2) the medial cord. Because the lower trunk is only accessible via the medial cord, any sensory fibers found to be traversing the lower trunk had to first traverse the medial cord. Similarly, those traversing the upper and middle trunks must first be a component of the lateral cord. The frequency that the various S-NCS responses were abnormal (unelicitable, below laboratory normal value, or < or = 50% of the contralateral response) for a given brachial plexus element lesion was as follows: (1) upper trunk (UT): 25 of 26 Med-D1, 25 of 26 LABC, 15 of 26 radial, 5 of 26 Med-D2, 2 of 26 Med-D3; (2) middle trunk (MT): 1 of 1 Med-D3; (3) lower trunk (LT): 25 of 26 Uln-D5, 22 of 23 DUC, 11 of 17 MABC, 3 of 23 Med-D3. With lower trunk brachial plexopathies, both "routine" (Uln-D5) and "uncommon" (DUC; MABC) S-NCS are abnormal. With upper trunk brachial plexopathies, in contrast, only the "uncommon" S-NCS (Med-D1; LABC) are consistently affected. The "routine" median S-NCS recording digit 2 (Med-D2) is far less reliable than the median S-NCS recording digit 1 (Med-D1) in detecting upper trunk axon loss brachial plexopathies. Additionally, the various pathways traversed by the fibers contributing to the individual S-NCS responses can be predicted, an important point when the full extent of a brachial plexus lesion is sought.

The electrodiagnostic examination with hysteria-conversion reaction and malingering

Electrodiagnostic examination (EDX) can be helpful in assessing patients with hysteria-conversion reaction (H-CR) and malingering. The EDX with both H-CR and malingering are identical, but the electromyographer usually distinguishes one from another based on how the patient responds to the situation. EDX not only can demonstrate that symptoms are probably nonorganic in nature, but also can show that symptoms attributed clinically to H-CR and malingering actually have an organic basis.

Sensory nerve conduction studies

Sensory nerve conduction studies (NCS) are an indispensable component of the electrodiagnostic examination. They evolved from mixed NCS, and were initially described by Dawson in 1950. Gilliatt and Sears first reported their clinical value in 1958. Compared to motor NCS, sensory NCS are much less standardized. Variables regarding them include: (a) bipolar vs. monopolar recording; (b) antidromic vs. orthodromic technique; (c) needle vs. surface stimulating electrode(s); (d) needle vs. surface recording electrodes; (e) fixed vs. variable distances between cathode and active recording electrode; (f) measuring latencies to onset vs. to peak; and (g) measuring amplitudes baseline to peak vs. peak to peak. The value of sensory NCS with various peripheral nerve fiber lesions, including plexopathies, mononeuropathies, and polyneuropathies, is discussed.

Causes and diagnosis of sensory neuropathies: a review

Sensory neuropathies are rare but unique peripheral neuropathies that involve only the peripheral sensory system. The diagnosis is made by both clinical and electrophysiological findings. Sensory neuropathies occur predominantly in women. The symptoms begin in the arms more often than the legs and occur asymmetrically. Pain and severe sensory ataxia in varying degrees are the main presenting symptoms. Definable causes of sensory neuropathies are hereditary, paraneoplastic, immunological, metabolic, infectious, and drug-induced disorders. In our experience, however, nearly half of all sensory neuropathies have been idiopathic. The clinical course of these sensory neuropathies is variable. The symptoms clearly worsened in 25% of our patients, but in the rest remained unchanged for many years, resulting in a poor functional prognosis because of intractable pain and ataxia. Most sensory neuropathies are resistant to any treatment. We review the electrophysiological features, laboratory findings, and nerve biopsy results in our patients and discuss in detail the potential underlying diseases included in the differential diagnosis.

High sciatic lesion mimicking peroneal neuropathy at the fibular head

We report 4 patients with severe, axon-loss, high sciatic mononeuropathies affecting exclusively the peroneal fibers: a boy with a slowly-growing nerve tumor, a woman with an injection injury, and 2 patients who had undergone proximal femur surgery. Clinically, the findings mimicked those seen with common peroneal neuropathy at the fibular head. The peroneal conduction studies were very low in amplitude/unelicitable. Conversely, the tibial studies and H-responses were normal in all; the sural responses were normal in one while low in amplitude/unelicitable in the remaining three. The biceps femoris, short-head, and all peroneal-innervated muscles showed fibrillations and profound motor unit loss. Conversely, the remaining hamstrings and all tibial-innervated muscles were normal. We conclude that a sciatic lesion can imitate a more distal peroneal lesion. Needle EMG of the biceps femoris, short head, is essential for correct diagnosis.

The electrodiagnostic examination with myopathies

The values and limitations of the electrodiagnostic examination in assessing patients with possible myopathies are discussed. Limitations include: (1) no findings are specific for muscle disease; (2) the particular changes may be quite diverse; (3) myopathies of different etiologies may have the same presentation, whereas the same myopathy may have different presentations at different times; (4) a specific myopathy cannot be diagnosed; and (5) the ability to diagnose myopathy may be seriously compromised by the presence of certain disorders. Benefits include: (1) widespread muscle sampling; (2) help in determining most appropriate muscle for biopsy; (3) ascertaining, to some extent, the type of myopathy present, depending on the particular findings; (4) distinguishing entities often confused clinically with myopathies; (5) recognizing abnormalities (e.g., myotonic discharges) otherwise undetectable. Both the clinical and electrodiagnostic presentations of myopathies are discussed. Regarding the latter, the potential or actual changes seen with each component of the electrodiagnostic assessment (nerve conduction studies, late responses, repetitive stimulation studies, needle electrode examination, quantitative electromyographic studies) is reviewed.

Perineurial cell hypertrophic mononeuropathy manifesting as carpal tunnel syndrome

A 42-year-old man showed signs and symptoms suggestive of carpal-tunnel syndrome, but EMG showed an isolated motor axon-loss lesion affecting the right median nerve distally. After the MRI revealed a mass in the median nerve, surgical exploration showed a diffusely swollen median motor branch. Biopsy showed a lesion with marked onion-bulb formation composed of perineurial cells as identified by immunohistochemical analyses and electron microscopic examination. Although we previously coined the term "perineurioma" for this condition, re-reviews of our cases do not support the idea that the onion-bulb lesion is a benign tumor; instead, it appears to be reactive hyperplasia. Although rare, electromyographers and neurologists need to be aware of this problem because it is self-limited and does not require surgical resection.

Spinal accessory (11th) nerve palsy following carotid endarterectomy

We report three cases of ipsilateral spinal accessory nerve palsy complicating carotid endarterectomy. Awareness of this cranial nerve injury, as a complication of this common surgical procedure, can lead to early diagnosis and avoids unnecessary investigations. This should be considered whenever such patients complain postoperatively of ipsilateral shoulder pain/weakness or "aching" about the ear, even if some time has elapsed since surgery.

Childhood peroneal neuropathy from bone tumors

Nontraumatic childhood peroneal mononeuropathy is uncommon and should initiate a search for surgically correctable causes. In 3 children, 2 age 12 years and 1 age 13 years, unilateral footdrop developed over a few days to a month. Electrodiagnostic findings demonstrated lesions with maximal or exclusive involvement of the deep peroneal nerve. Radiologically, bony exostoses were identified at or near the fibular head in each patient. In 2 patients, the lesions were clinically occult. An osteochondroma was removed from each patient and 2 patients had excellent clinical recoveries.

Thoracic outlet syndromes: a plea for conservatism

This article focuses on the controversial subtype of TOS, which presents primarily sensory sentence, normal neurologic examination, normal electrodiagnostic study results, and normal neck x-ray films. At present, this entity is so variable in its "typical" presentation that it has no characteristic profile. Although some physicians now are attempting to narrow its boundaries, the goal of fashioning a syndrome that has general acceptance remains to be achieved, consequently, neurosurgeons who do not now perform TOS surgery, but are contemplating doing so, are urged to review the literature critically on the subject first, and to err toward conservatism.

Electrodiagnostic testing of neurologic injuries in athletes

In this article the value and limitations of the EMG examination in assessing patients with known or suspected sports-related nerve injuries is reviewed. The basic components of the EMG examination--the nerve conduction studies (NCS) and the needle electrode examination (NEE)--are described, and their components are defined. The types of pathophysiology produced by focal nerve lesions is detailed, and their effects on the various portions of the EMG examination are described. Of note is that the two processes that cause clinical weakness, conduction block and conduction failure (axon loss), both alter the NCS amplitudes, without having any appreciable effect on the rate of impulse conduction along the nerve fibers that can still conduct across the lesion site. For this reason, the most widely known NCS parameter, the conduction velocity, is of very little value with the acute type of nerve lesion usually encountered in sports. The fact that fibrillation potentials, seen on NEE, are the most sensitive indicator of motor axon loss, is noted, as is the fact that they do not appear until some 3 weeks following nerve injury. Our EMG laboratory experience with sports-related nerve injuries is reviewed. The majority of patients were engaged in contact sports (especially football). The majority of lesions affected primarily the shoulder girdle region, although a variety of disorders (radiculopathies, brachial plexopathies, various mononeuropathies) were found. Some of the difficulties in the EMG assessment of this region are reviewed, as well as the clinical and EMG findings with three entities, "burners," acute brachial neuropathy, and rotator cuff tears, which affect it and which occur in athletes.

Hypertrophic mononeuritis clinically presenting with painful legs and moving toes

A 40-year-old woman presented with progressive lower leg pain and spontaneous toe movement. The EMG showed a posterior tibial nerve mononeuropathy and continuous myokymic discharges in posterior tibial-innervated muscles. The MRI revealed a markedly enlarged posterior tibial nerve. Toe movements and myokymia were unaffected by the proximal transection of the lesion but ceased abruptly when the distal end of the fusiform "tumor" was resected, suggesting that spontaneous electrical foci may have been located along the nerve lesion. The markedly enlarged nerve segment contained edematous, swollen fascicles with marked Schwann cell onion-bulb lesions and angiocentric, lymphocytic, and lymphofollicular infiltration. This nerve lesion is an example of a newly recognized entity called hypertrophic mononeuritis.

Acute brachial neuropathy in athletes

Acute brachial neuropathy is an uncommon etiology of shoulder pain and disability. It can, however, present in association with athletic activity and therefore must be included in the differential diagnosis of athletes with such symptomatology. Findings that should alert the examiner to the possible presence of acute brachial neuropathy include 1) onset with noncontact as well as contact sports, 2) rather acute onset of pain without specific inciting trauma, 3) persistent, often severe pain that continues despite rest, 4) patchy brachial plexus and/or peripheral nerve involvement, and, 5) dominant arm predominance of symptoms and signs. Electromyography and nerve conduction studies often can confirm the diagnosis. Treatment begins with rest and continues through a rehabilitation phase. Followup of athletes with acute brachial neuropathy discloses that weakness may persist in the affected muscles. Absolute strength parity may be difficult to achieve, so permission to participate in athletics must be given on a case by case basis.

Common peroneal mononeuropathy: a clinical and electrophysiologic study of 116 lesions

We analyzed the clinical and electromyographic (EMG) findings of 116 common peroneal mononeuropathies in 103 patients (13 with bilateral lesions). Prior to the EMG examination, the diagnosis was not clinically suspected or seriously considered in 44% of the lesions. Sensory manifestations were common (79%) but pain was rare (16.5%). The onset was acute in 57 patients, gradual in 35, and indeterminate in 11. Of the 116 lesions, 64 were solely axonal loss in type, 23 manifested as conduction block, presumably secondary to focal demyelination, and 29 were a mixture of the two. Contrary to common belief, the pathophysiology was predominantly axonal loss regardless of etiology, including those that developed perioperatively. The peroneal motor nerve conduction study, recording tibialis anterior muscle, was the single most important electrophysiologic study; it localized all 52 lesions causing conduction block at the fibular head. In contrast, peroneal motor conduction velocity along the knee-to-fibular head segment was seldom abnormal, with slowing in only five of the 52 cases.

AAEE minimonograph #32: the electrophysiologic examination in patients with radiculopathies

A brief history of the evolution of radiculopathy as a clinical entity, and the use of electrodiagnostic studies to diagnose it, are provided. Root anatomy and the concept of myotomes and dermatomes are reviewed, as is the pathophysiology of radiculopathy. The value and limitations of the various electrophysiologic procedures used in the diagnosis of radiculopathies are discussed, including motor and sensory nerve conduction studies, late responses, somatosensory evoked potentials, nerve root stimulation, and the needle electrode examination. The specific muscles are enumerated which most often appear abnormal on needle electromyography with lesions of the various roots. The electrodiagnostic differentiation of root lesions from plexus lesions is described, and the various electrodiagnostic findings with lumbar canal stenosis are discussed. Finally, the value and limitations of the electrodiagnostic assessment in the evaluation of patients with suspected radiculopathies are reviewed.

Solitary primary lymphoma of the sciatic nerve: case report

An unusual case of a solitary extranodal primary lymphoma of the sciatic nerve in a patient presenting with sciatica and a left footdrop is described. Magnetic resonance imaging was successful in identifying a fusiform lesion in the sciatic nerve in the left infragluteal region. Surgical exploration and biopsy confirmed this as a B cell lymphoma. An extensive metastatic work-up has not identified other sites of lymphomatous involvement.

Thoracic outlet syndrome surgery causing severe brachial plexopathy

Hundreds of first rib resections are performed yearly in the United States to treat a controversial type of neurogenic thoracic outlet syndrome (NTOS). This surgery was thought to be devoid of serious neurological complications until 1982. However, that year Dale unearthed the rather astounding fact that the members of a single surgical society were aware of nearly 300 brachial plexus injuries resulting in motor deficits that had occurred during such operations, although almost none had been reported in the literature. In this report the features of the two main types of NTOS ("true" and "disputed") are discussed. The history of brachial plexus injury occurring during TOS surgery is traced back to the late nineteenth century. The clinical and electrophysiological features of eight patients who sustained such injuries are described in detail, the literature on this topic is reviewed, and the location and causes for these injuries are discussed.