Hand muscle atrophy in multiple sclerosis.

The occurrence of muscular atrophy in multiple sclerosis (MS) has been considered unusual and classically has been ascribed to disease involving the motor unit. Nine patients with MS in a single clinic were found by strict criteria to have focal hand muscle atrophy associated with weakness. None had electrodiagnostic evidence of either anterior horn cell or axonal abnormalities. These observations indicate that focal muscular atrophy is common in MS; it may often occur as a result of relative disuse resulting from disease of central pathways involved in motor control.

Paralytic shellfish poisoning: a case report and serial electrophysiologic observations.

We report serial electrophysiologic observations in a patient with acute bulbar and respiratory paralysis following ingestion of saxitoxin-contaminated clams. Prolonged distal motor and sensory latencies, slowed conduction velocities, and moderately diminished amplitudes were present at the outset. All values returned to normal over 5 days. These findings, the result of incomplete sodium channel blockade, distinguish paralytic shellfish poisoning from most other acute paralytic illnesses.

Reversible somatosensory evoked potential changes with neodymium: yttrium-aluminum-garnet laser use.

Reversible prolongation and dissolution of the tibial somatosensory evoked potential (SEP) was observed with operative use of the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser during extirpation of a foramen magnum meningioma. Rapid normalization of the SEP followed irrigation with cool saline. The absence of postoperative dorsal column deficit suggests that heat-related physiological changes occurred before the point of irreversible tissue injury. Should intraoperative SEP monitoring prove a reliable index of tissue temperature, it could enable safer use of the Nd:YAG laser in the vicinity of the spinal cord and brain stem.

Angiotropic lymphoma (intravascular large cell lymphoma) presenting with cauda equina syndrome.

A 50-year-old man developed cauda equina syndrome of unknown etiology that was stable for 20 months. Two months prior to sudden death, he experienced new back pain, confusion, seizures, and multiple cranial nerve palsies. Neuropathologic examination revealed angiotropic lymphoma without parenchymal involvement or infarcts in the brain, spinal cord, and muscle. In addition, nerve roots in the cauda equina contained angiotropic lymphoma and infarcts of various ages. Angiotropic lymphoma should be considered as a cause of cauda equina syndrome and of disorders that affect the central and peripheral nervous systems concurrently.

Increased levels of IgE and autoreactive, polyreactive IgG in wild rodents: implications for the hygiene hypothesis.

To probe the potential role of Th1 versus Th2 reactivity underlying the hygiene hypothesis, intrinsic levels of Th1-associated and Th2-associated antibodies in the serum of wild rodents were compared with that in various strains of laboratory rodents. Studies using rat lung antigens as a target indicated that wild rats have substantially greater levels of autoreactive, polyreactive immunoglobulin G (IgG), but not autoreactive, polyreactive IgM than do laboratory rats, both on a quantitative and qualitative basis. Increased levels of serum IgG and IgE were observed in both wild rats and wild mice relative to their laboratory-raised counterparts, with the effect being most pronounced for IgE levels. Further, wild rats had greater intrinsic levels of both Th1- and Th2-associated IgG subclasses than did lab rats. The habitat (wild versus laboratory raised) had a more substantial impact on immunoglobulin concentration than did age, strain or gender in the animals studied. The presence in wild rodents of increased intrinsic, presumably protective, non-pathogenic responses similar to both autoimmune (autoreactive IgG, Th1-associated) and allergic (IgE, Th2-associated) reactions as well as increased levels of Th1-associated and Th2-associated IgG subclasses points toward a generally increased stimulation of the immune system in these animals rather than a shift in the nature of the immunoreactivity. It is concluded that, at least to the extent that feedback inhibition is a controlling element of immunoreactivity, an overly hygienic environment may affect the threshold of both types of immune responses more so than the balance between the different responses.

Pitcher's arm: an electrodiagnostic enigma.

Every major league baseball pitcher, most minor league pitchers, but only few amateur pitchers that we have studied have had reduced sensory nerve action potentials in the throwing arm. We present 6 clinical cases which demonstrate the spectrum of "pitcher's arm." These cases suggest that the phenomenon is a pathologic process, probably an example of a repetitive use syndrome affecting the brachial plexus. Although it does not appear to impact performance, it has clear implications for the interpretation of electrodiagnostic studies in symptomatic pitchers.

Topographic mapping of brain electrical activity in the assessment of central auditory nervous system pathology.

Topographic mapping of brain electrical activity is a method of converting electrical measurements of brain activity (evoked potential and EEG) into quantitative data that then can be displayed as colored visual maps. In this article, we review the basic principles underlying the procedures involved and then discuss their use in the assessment of central auditory nervous system (CANS) pathology. Finally, we highlight some of the limitations of the procedures as presently used.