Diagnostic accuracy and certainty from sequential evaluations in peripheral neuropathy

Three masked neuromuscular experts analyzed the contribution of the data from sequential evaluations in predicting specific varieties of peripheral neuropathy in 72 patients. The largest improvement (16%) in diagnostic accuracy resulted from presentation of neurologic history. By contrast, diagnostic confidence increased gradually with presentation of additional medical information. Therefore, the authors conclude that for diagnostic accuracy and certainty, expert neuromuscular judgment and extensive characterizing or discriminative testing are needed.

Classification of teased nerve fibers for multicenter clinical trials

Teased nerve fibers are used widely in both clinical and experimental neuropathology, but anecdotal evidence indicates that even experienced readers find little agreement on categories for teased fiber classification. To develop a classification scheme that could be used and understood by both experienced and naive readers, specific criteria were developed for normal fibers and those exhibiting Wallerian degeneration, demyelination, hypomyelination, remyelination, and abnormal paranodal myelination. Twenty fibers teased from human sural nerve biopsies were selected as examples of one or more of these categories. Ten readers, including seven having no previous experience with teased fibers, were given a set of instructions and asked to score each fiber for all matching categories. These readers averaged high rates of true positive (56-85%) classifications, while average false positive (3-18%) rates were much lower. Among the three experienced readers, true positive agreements averaged between 75 and 100% across the fiber classifications. False positives were correspondingly low, ranging between 0 and 8%. These results suggest that it is possible to design an easily learned, meaningful scheme for classifying teased nerve fibers.

Role of the blink reflex in the evaluation of sensory neuronopathy

Because of an incidental observation that the blink reflex was normal in paraneoplastic sensory neuronopathy (SN) and frequently abnormal in nonparaneoplastic SN, the authors reviewed the electromyographic records of patients with SN in whom blink reflex studies were performed. The blink reflex was normal in all 17 patients with paraneoplastic SN and abnormal in 20 of 43 patients with nonparaneoplastic SN. Although it does not exclude paraneoplastic SN, an abnormal blink reflex favors a nonparaneoplastic etiology.

Acquired peripheral neuropathy

This article reviews the acquired causes of polyneuropathy other than diabetic and acute-onset neuropathies. The author gives a general method to simplify the diagnosis of chronic polyneuropathy. The acquired polyneuropathies are discussed under four main headings: metabolic disorders, toxic or deficiency states, infections, and immune-mediated. Recent advances in therapy are emphasized, and some illustrative case histories are provided.

Seronegativity for type 1 antineuronal nuclear antibodies ('anti-Hu') in subacute sensory neuronopathy patients without cancer

We followed 21 patients with sensory neuronopathy without evidence of cancer for up to 23 years. All were seronegative for type 1 antineuronal nuclear antibodies (ANNA-1, also called "anti-Hu"). We additionally studied 67 seropositive patients with sensory neuropathy or a related neurologic syndrome. Ninety-one percent of the seropositive patients had a small-cell lung carcinoma. One, with a normal chest x-ray, had been followed for 7 years for sensory neuronopathy of indeterminate cause before serologic testing for ANNA-1 led to the discovery of the tumor by CT. We conclude that ANNA-1 seropositivity in a patient with sensory neuronopathy is strong evidence for an underlying small-cell lung cancer.

Anti-neutrophil cytoplasmic antibodies in vasculitis peripheral neuropathy

Anti-neutrophil cytoplasmic antibodies (ANCA) have been reported to be specific serologic markers of systemic necrotizing vasculitis. We looked for ANCA in 166 consecutive patients referred for evaluation of peripheral neuropathy, wondering if ANCA might be helpful in diagnosing vasculitic neuropathy. ANCA were found in four of six patients with vasculitic neuropathy. However, false-positive results limited the diagnostic usefulness of ANCA in peripheral neuropathy.

Application of immunohistochemical techniques to sural nerve biopsies

The role of immunohistochemistry in the day-to-day diagnostic work of a peripheral nerve laboratory is not yet clearly established, although for conditions such as amyloid neuropathy, immunohistochemistry appears to be a useful adjunct to conventional techniques. Immunohistochemistry has provided new information about some neuropathies in which immune dysfunction is believed to play a central role. Immunohistochemical data about normal human nerve are scarce; a better appreciation of the normal cellular constituents of nerve, particularly the endoneurium, is needed. In the future, the techniques may be a means to understand better the pathogenesis of other types of neuropathy, such as inherited or toxic neuropathies, or to examine fundamental pathologic events such as axonal degeneration.

The distinctive clinical features of paraneoplastic sensory neuronopathy

A 15-year experience with paraneoplastic sensory neuronopathy at the Mayo Clinic is reviewed. Of 26 patients with paraneoplastic sensory neuropathy, 19 had small cell lung cancer, 4 had breast cancer, and 3 had other neoplasms. There was a striking predominance of females (20:6). Neuropathic symptoms (pain, paresthesia, sensory loss) were asymmetric at onset, with a predilection for the upper limbs; in three patients, symptoms were confined to the arms. Electrophysiologic testing revealed absent sensory responses and normal or minimally altered motor responses. Slightly more than half the patients had associated autonomic, cerebellar, or cerebral abnormalities. In some patients, treatment of the neoplasm seemed to halt progression of the neuronopathy, but none had neurologic improvement and most continued to worsen, even when the oncologic response was good. Distinguishing between paraneoplastic and nonparaneoplastic sensory neuronopathies can be difficult, but prominent neuropathic pain, neurologic dysfunction involving more than the peripheral sensory system, or an increased cerebrospinal fluid protein value should prompt a careful search for a cancer.

Cryptococcal meningitis manifesting as epilepsia partialis continua of the abdomen

We report a case of epilepsia partialis continua that primarily involved the abdominal muscles. Thorough assessment ultimately showed that the condition was due to cryptococcal meningitis. Surface electrode electromyography and electroencephalography were helpful in analyzing this unusual epileptic phenomenon. An 8-week treatment regimen of amphotericin B and a 30-day course of 5-fluorocytosine abolished the epilepsia partialis continua and cured the meningitis. This case should alert physicians to the fact that patients with epilepsia partialis continua may have clonic movements of only the trunk and that the spectrum of neurologic manifestations of cryptococcal infection must now include this seizure disorder.

Response of the Lambert-Eaton myasthenic syndrome to treatment of associated small-cell lung carcinoma

We evaluated the outcome in 16 patients with Lambert-Eaton myasthenic syndrome (LEMS) associated with histologically verified small-cell carcinoma (SCC). Thirteen patients received specific tumor therapy (chemotherapy, radiation therapy, or resection) and most also received pharmacologic and immunologic treatment for LEMS. Seven of 11 patients surviving for more than 2 months after tumor therapy showed substantial neurologic improvement (1 patient being in complete remission at 7 years); in 3 of 11 improvement was transient. An EMG index of disease severity (compound muscle action potential amplitude in abductor digiti minimi) was significantly increased at final follow-up (p less than 0.01; n = 11). A pretreatment amplitude greater than 3.0 mV was a good prognostic sign. We conclude that a combined treatment approach in SCC-LEMS usually results in neurologic improvement.

Familial multiple symmetric lipomatosis with peripheral neuropathy

We describe coexisting peripheral neuropathy and multiple symmetric lipomatosis in 4 of 7 siblings. The absence of either condition in 3 other generations of this family suggests autosomal recessive inheritance. None of the affected siblings were alcoholic, a factor some have proposed to explain the frequent occurrence of peripheral neuropathy in sporadic multiple symmetric lipomatosis. Serum lipid studies, including apoprotein A levels, were normal. Sural nerve biopsy from 1 patient showed nerve fiber loss, predominantly affecting large myelinated fibers. The relationship between myelin sheath thickness and axon diameter was normal, arguing that this neuropathy is not due to primary axonal atrophy.