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Biomedical subjects

A J Wilbourn

Publications and source records attributed to A J Wilbourn.

At least 19 recordsLinked to original sources
PubMed1996

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.

Adult↗
PubMed1995

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.

Action Potentials↗
PubMed1995

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.

Conversion Disorder↗
PubMed1994

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.

Action Potentials↗
PubMed1994

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.

Adult↗
PubMed1994

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.

Action Potentials↗
PubMed1993

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.

Electrodiagnosis↗
PubMed1992

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.

Adult↗
PubMed1992

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.

Accessory Nerve↗
PubMed1991

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.

Brachial Plexus↗
PubMed1990

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.

Adult↗
PubMed1990

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.

Athletic Injuries↗