The clinical spectrum of isolated peripheral motor dysfunction.

INTRODUCTION: Isolated peripheral motor dysfunction due to lower motor neuron or peripheral nerve disorders presents an interesting challenge to clinicians because of the diverse differential diagnosis with a broad range of prognoses. METHODS: We retrospectively reviewed clinical data of adults who presented over 12 years with muscle weakness, atrophy, or fasciculations, but without hyperreflexia or sensory involvement. RESULTS: In 119 patients, 52% had a motor neuron disease (MND), 13% had immune neuropathies, 11% had genetic neuronopathies, 10% had residual or post-polio syndrome, 5% had benign fasciculation, 1% had an infectious etiology, and 8% were not given a final diagnosis. Only MND patients had cognitive dysfunction or frontal release signs. Bulbar and respiratory symptoms virtually excluded consideration of immune neuropathy. CONCLUSIONS: Only half of the patients were diagnosed with MND. A significant minority have treatable conditions. Cognitive involvement, frontal release signs, and bulbar or respiratory symptoms are strongly suggestive of MND.

Laboratory evaluation of suspected motor neuron disease: A survey of physicians.

INTRODUCTION: The clinical diagnosis of amyotrophic lateral sclerosis (ALS) relies on exclusion of mimic syndromes, but there are no specific guidelines regarding the extent of laboratory testing required. METHODS: A survey was sent to 274 physicians listed in the Neuromuscular Section of the American Academy of Neurology. The survey asked how often they order 21 different laboratory tests in patients suspected of having ALS. RESULTS: Ninety-nine responses were received (36% response rate). Greater than 75% ordered serum creatine kinase, chemistry panel, and thyroid functions often or always. Fewer than 25% tested for serum complement, hexosaminidase A, spinal muscular atrophy, Kennedy disease, heavy metals, or human T-cell lymphotrophic virus often or always. Twelve other tests had intermediate responses. CONCLUSIONS: There is a lack of consensus among respondents regarding the laboratory evaluation of suspected ALS. Prospective studies are needed to define the diagnostic yield and cost-effectiveness of laboratory testing in this population.