Sensory neuropathy in vasculitis: a clinical, pathologic, and electrophysiologic study

BACKGROUND

Vasculitis is not usually considered as a cause of symmetric sensory neuropathy.

OBJECTIVE AND METHODS

To present the clinical, pathologic, and electrophysiologic features of 17 (16%) cases of sensory neuropathy in vasculitis (SNV) among 106 cases with histologically proven vasculitic neuropathy that were collected over the last 30 years.

RESULTS

In 41% of cases, SNV was found as systemic vasculitic neuropathy in association with primary vasculitic disease. The most common clinical presentation was symmetric polyneuropathy, seen in 53% of cases. The most common nerve conduction pattern was diffuse neuropathy pattern of axonal degeneration. Sural nerve biopsy was diagnostic in 88% of cases. In two cases, muscle biopsy was necessary for the definite diagnosis of vasculitis. Non-systemic SNV is usually benign. Of 11 patients followed for longer than 2 years, none developed motor weakness due to neuropathy.

CONCLUSION

Sensory neuropathy, regardless of symmetry, can be due to vasculitis.

Subacute inflammatory demyelinating polyneuropathy

OBJECTIVE

To report the clinical, electrophysiologic, and histologic characteristics of subacute inflammatory demyelinating polyneuropathy (SIDP) and to present the diagnostic criteria of this disease.

METHODS

For a diagnosis of "definite SIDP," there were four mandatory criteria: 1) progressive motor and/or sensory dysfunction consistent with neuropathy in more than one limb with time to nadir between 4 and 8 weeks, 2) electrophysiologic evidence of demyelination in at least two nerves, 3) no other etiology of neuropathy, and 4) no relapse on adequate follow-up. Supportive criteria included high spinal fluid protein level (>55 mg/dL) and inflammatory cells in the nerve biopsy. A diagnosis of "probable SIDP" required progression of demyelinating neuropathy over a 4- to 8-week period.

RESULTS

Sixteen definite SIDP patients were identified among 29 probable SIDP patients. An antecedent infection was found in 38% of cases. The two most common neuropathy types were a symmetric motor-sensory neuropathy and a pure motor neuropathy. Cranial nerve deficits and respiratory failure were rare. Spinal fluid protein was high in 93% of cases. Demyelination was documented by the motor nerve conduction in 88% of cases and by the near-nerve needle sensory nerve conduction in two cases. Almost all patients were treated with prednisone and some with additional immunotherapies. Complete recovery was achieved in 69% of cases and partial recovery in others. Definite SIDP had all the characteristics of CIDP with three exceptions: a higher rate of antecedent infection, no relapse rate, and a high rate of recovery to normal.

CONCLUSION

Subacute inflammatory demyelinating polyneuropathy is a definite entity bridging the gap between Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy.

Postexercise facilitation of reflexes is not common in Lambert-Eaton myasthenic syndrome

Postexercise facilitation (PEF) with clinical reflexes, H-reflex, and T-reflexes at the ankle and knee was systematically studied in 16 patients with Lambert-Eaton myasthenic syndrome (LEMS). PEF was observed in ankle and knee deep tendon reflexes in five patients, in H-reflex in three patients, and in T-reflexes in six patients. When all reflex tests were combined, 7 (43.7%) of 16 patients showed PEF by at least one test. The authors conclude that the PEF of reflexes, the most helpful diagnostic clinical marker for LEMS, is not common.

Large-fiber neuropathy in distal sensory neuropathy with normal routine nerve conduction

Near-nerve needle sensory nerve conduction of plantar nerves in 100 patients with distal sensory neuropathy with normal routine nerve conduction (DSN-NNC) found the definite neuropathy pattern (abnormality in more than three of six tested nerves) in 65%, axonal neuropathy in 35%, and the known cause in 37% of patients. Absent or diminished reflexes were a reliable indicator for large fiber neuropathy (LFN). This near-nerve needle plantar nerve study provides useful and unequivocal evidence of its value in identifying neuropathy in DSN-NNC by finding LFN in 65% of patients.

Distal sensory nerve conduction of the superficial peroneal nerve: new method and its clinical application

The superficial peroneal nerve subserves sensation on the entire surface of the dorsum of the foot, except in small areas. All previously reported techniques for evaluating nerve conduction along this nerve tested a proximal portion of the nerve. We report a new method for evaluating sensory nerve conduction of the four branches of the distal superficial peroneal nerve. Two branches to the second and third toes of the medial dorsal cutaneous nerve and two branches to the fourth and fifth toes of the intermediate dorsal cutaneous nerve were studied orthodromically and antidromically in 37 feet of 21 normal volunteers using surface stimulating and recording electrodes and with a distance of 10 cm between the stimulating and recording electrodes. Maximum nerve conduction velocities (NCV) ranged from 41.8 to 46.9 m/s, and mean response amplitude ranged from 6.5 to 7.6 microV with the orthodromic technique. Values for NCV were almost identical when elicited by antidromic and orthodromic techniques, but response amplitudes were higher with the antidromic technique. Mean amplitudes of the distal superficial peroneal nerve were about 50% of the proximal superficial peroneal, and the conduction velocity in the distal superficial peroneal was slower than that in the proximal superficial peroneal nerve, by 8-14 m/s. In seven cases, distal superficial peroneal neuropathy was confirmed with this technique: two with proper digital neuropathy, two with medial dorsal cutaneous neuropathy, and three with intermediate dorsal cutaneous neuropathy.

Sensory Guillain-Barré syndrome

OBJECTIVE

To report eight cases of sensory Guillain-Barré syndrome (GBS).

BACKGROUND

The concept of sensory equivalent to ascending paralysis of GBS was raised in 1958, and the diagnostic criteria for a sensory loss and areflexia variant of GBS were proposed in 1981. However, clinical cases meeting these criteria have been relatively scarce.

METHODS

During a 13-year period between 1986 and 1999, the authors collected eight cases of an acute sensory demyelinating neuropathy that met most of the proposed diagnostic criteria of a sensory variant of GBS.

RESULTS

In all patients, sensory neuropathy was sudden at onset and peaked to maximal deficit within 4 weeks. In five (63%) cases, there was an antecedent viral illness. All patients had objective sensory loss and diminished or absent reflexes. None showed any muscle weakness. In all four patients in whom the spinal fluid was examined during the first 4 weeks, there was albuminocytologic dissociation. All of the patients had electrophysiologic evidence of demyelination in at least two nerves. Demyelination was demonstrated in motor nerve conduction in seven patients and in sensory nerve conduction in one, indicating that motor nerve conduction studies were the key for the diagnosis of demyelinating neuropathy. All patients had sensory nerve conduction abnormalities in at least one nerve. Three patients responded to immunotherapies. All had a favorable outcome, with a monophasic course of disease and no sign of relapse.

CONCLUSION

The current study confirms the existence of sensory GBS.

Motor and sensory demyelinating mononeuropathy multiplex (multifocal motor and sensory demyelinating neuropathy): a separate entity or a variant of chronic inflammatory demyelinating polyneuropathy?

We report 16 patients with motor and sensory demyelinating mononeuropathy multiplex (MSDMM) or multifocal motor and sensory demyelinating neuropathy (MMSDN). These patients had the clinical pattern of motor and sensory mononeuropathy multiplex, electrophysiological evidence of demyelination including conduction block, and segmental demyelination in the sural nerve biopsy. Sixty per cent of patients had high CSF protein. Eighty per cent of patients showed good responsiveness to steroid treatment. Unlike multifocal motor neuropathy (MMN), MSDMM is characterized by a shorter course, sensory deficits and sensory nerve conduction abnormalities, absence of GM1 antibody in most patients tested, and a good response to steroid therapy. We believe that MSDMM represents a variant of chronic inflammatory demyelinating polyneuropathy (CIDP) and an intermediate link between CIDP and MMN.

Ice-pack test in myasthenia gravis: electrophysiological basis

We report the first study in which the repetitive nerve stimulation (RNS) test was performed in conjunction with the ice-pack test in three patients with myasthenia gravis. All three patients showed an unequivocal improvement in ptosis on the side where an ice pack was placed. RNS test in the facial nerve revealed a definite improvement in the decremental response. From this we conclude that the ice-pack test produces a clinical and electrophysiological improvement in myasthenia gravis.

Diagnostic value of nerve and muscle biopsy in suspected vasculitis cases

OBJECTIVES

To evaluate the diagnostic value of nerve and muscle biopsy in suspected cases of vasculitis and their correlation with the clinical and electrophysiological data.

METHOD

We conducted a retrospective review of I 15 nerve and muscle biopsy specimens from cases in the past 20 years at the University of Alabama at Birmingham (UAB) Muscle and Nerve Histopathology Laboratory. Clinical and electromyography data in available cases were analyzed to evaluate the histopathologic correlation,:

RESULTS

: The diagnostic sensitivity of nerve biopsy was 39%, Nerve biopsy showed a statistically higher diagnostic yield (P = 0-0001) than muscle biopsy (17%), although muscle biopsies resulted in a more definite diagnosis m 3%. of cases. The highest diagnostic yield (73%) of vasculitis on nerve biopsy was observed in patients with known rheumatologic disease and accompanying neuropathy or myopathy. Nerve conduction study was able to identify diffuse neuropathy in the majority of patients with vasculitis, including asymptomatic neuropathy. Abnormal sural nerve conduction was highly correlated (P = 0.03) with positive nerve biopsy. There was a wide spectrum of neurologic manifestations in vasculitic neuropathy, with the most common clinical manifestation of vasculitic neuropathy being polyneuropathy.

CONCLUSIONS

Nerve biopsy is superior to muscle biopsy for the diagnosis of vasculitis among suspected cases of vasculitis. The highest diagnostic yield of nerve biopsy is observed when patients with known rheumatologic diseases have neuropathy or myopathy. Abnormal sural nerve conduction can be used as a guide for nerve biopsy.

New near-nerve needle nerve conduction technique: differentiating epicondylar from cubital tunnel ulnar neuropathy

At the elbow, the ulnar nerve is compressed most commonly either in the epicondylar groove or at the cubital tunnel. While conventional electrodiagnosis may localize an ulnar neuropathy to the elbow, separating epicondylar syndrome (tardy ulnar nerve palsy) from cubital tunnel syndrome is more difficult. We describe a new method using a near-nerve needle technique for distinguishing these two types of ulnar neuropathy at the elbow. We placed three active needle electrodes across the elbow: the first was 4 cm above, and the second and third were 1.5 cm and 6 cm below the medial epicondyle, respectively. The latter two points were chosen because of the presence of the cubital tunnel in this segment. Sensory, motor, and mixed nerve conduction studies (NCS) were performed on these two segments (elbow segment and cubital tunnel segment) in 26 normal nerves and normal data were established. We also present 7 cases of epicondylar ulnar nerve palsy and 1 case of cubital tunnel syndrome in which we were able to confirm the diagnosis with the present method. In 3 cases of epicondylar ulnar nerve palsy, the present method accurately localized the lesion when other methods failed. We believe that this method will be helpful in distinguishing cubital tunnel syndrome from epicondylar ulnar nerve palsy, especially in early ulnar neuropathy in which only sensory fibers are involved.

Anti-Hu-associated paraneoplastic sensory neuropathy responding to early aggressive immunotherapy: report of two cases and review of literature

Anti-Hu-associated paraneoplastic sensory neuropathy (PSN) has been reported to be nonresponsive to immunotherapy or cancer therapy. We report 2 patients with anti-Hu-associated PSN who achieved sustained clinical improvement with early and aggressive immunotherapy 10-15 months before the diagnosis of small-cell lung carcinoma. Both had chronic "sensory neuronopathy plus"; in addition to sensory neuronopathy, case 1 had a motor-autonomic dysfunction with encephalopathy, and case 2 had a motor-autonomic dysfunction with swallowing difficulty. These two cases were unusual in that sustained clinical improvement was achieved with early aggressive immunotherapy before the detection of cancer and without any concomitant anticancer therapy or lowering of anti-Hu antibody titer. We believe that early and aggressive immunotherapy should be tried in any patient with anti-Hu-associated PSN, as it may induce sustained clinical improvement.

Low-dose guanidine and pyridostigmine: relatively safe and effective long-term symptomatic therapy in Lambert-Eaton myasthenic syndrome

Guanidine hydrochloride is known to be highly effective in the symptomatic treatment of the Lambert-Eaton myasthenic syndrome (LEMS). However, because of its potentially dangerous side reactions of hematologic abnormalities and renal insufficiency, 3,4-diaminopyridine, which is not readily available in the United States, is recommended as the preferred drug for LEMS. We used low-dose guanidine and pyridostigmine combination therapy in 9 patients with LEMS and analyzed its long-term safety and effectiveness. In all patients, a liberal amount of pyridostigmine was used, while daily guanidine dose was kept below 1000 mg a day, and guanidine was given between pyridostigmine dosings. This combination therapy was used for 3-102 months (mean: 34.1 months) and improved clinical status in all patients. Although guanidine had to be discontinued due to severe gastrointestinal symptoms in 3 cases, no serious side reactions such as bone marrow suppressions or signs of renal insufficiency developed in any case. Thus, we conclude that low-dose guanidine therapy is relatively safe and effective for long-term symptomatic treatment of LEMS when it is combined with pyridostigmine.

Stiff-persons' syndrome associated with thymoma and subsequent myasthenia gravis

We report the first case of stiff-persons' (-man) syndrome in the setting of a histologically proven thymoma. Muscular hyperactivity was abolished under general anesthesia and the symptoms of stiffness resolved after thymectomy and three courses of intravenous immunoglobulins. After thymectomy, the patient developed ocular myasthenia gravis which later resolved spontaneously. We suggest that thymoma be sought for in cases with neuromuscular hyperactivity syndromes. Myasthenia gravis may develop subsequently in these cases.

Isaacs' syndrome associated with chronic inflammatory demyelinating polyneuropathy

We report the first case of Isaacs' syndrome in which an inflammatory demyelinating neuropathy was documented histologically. For 9 months, the patient developed slowly progressive weakness, muscle spasms and stiffness, fasciculations, and myokymia in the arms, which were unmodified by sleep. Nerve conduction studies showed multifocal motor conduction block, abnormal dispersion phenomenon, and abnormal sensory and mixed nerve conduction. Needle electromyogram showed continuous motor unit potentials at rest with bursts of rapid-firing discharges which were unaffected by spinal anesthesia but diminished by peripheral nerve block and completely abolished by local curarization. Sural nerve biopsy demonstrated an inflammatory demyelinating neuropathy. Muscle cramping, twitching, and stiffness responded to phenytoin. The patient's weakness gradually responded to prednisone and azathioprine. Over a 17-year period, the patient had three relapses which were well controlled with prednisone and azathioprine. At this time, the patient is symptom-free without any medication.

Multifocal demyelinating motor neuropathy: pathologic evidence of 'inflammatory demyelinating polyradiculoneuropathy'

We report a case of multifocal demyelinating motor neuropathy in a patient with a 5-year history of progressive, asymmetric, predominantly motor weakness characterized by multifocal progression, multifocal conduction block, and lack of response to steroid therapy. Neuropathologic findings at autopsy showed an "inflammatory demyelinating polyradiculoneuropathy" in the motor cranial nerves and motor roots of peripheral nerves, an extensive deposition of IgG and focal accumulations of IgM in the peripheral nerve motor roots, and loss of motor neurons. These findings clearly document an inflammatory demyelinating polyradiculoneuropathy in multifocal demyelinating motor neuropathy, suggesting a close relation with chronic inflammatory demyelinating polyneuropathy.

Modified trichrome staining technique of the nerve to determine proximal nerve viability

Normal myelinated fibers are stained "red" by modified trichrome staining of the frozen section of the nerve. We have used this technique for rapid assessment of the anatomical integrity of the proximal nerve stump by identifying well-preserved myelinated fibers. This technique can also identify degenerating and degenerated myelinated fibers, fibrosis, and inflammatory cells. We report three cases in which the practical usefulness of this technique is demonstrated.