Femoral and obturator neuropathies.

Femoral, saphenous, and obturator neuropathies have diverse causes, many of which are iatrogenic. They have overlapping, but distinct, clinical features. Electrodiagnostic testing can distinguish between these disorders and others in the differential diagnosis. Imaging studies may demonstrate the origin of the neuropathy in some cases. Conservative treatment is usually sufficient, but occasionally surgical exploration of the affected nerve is indicated.

Neurology in the electronic information age.

This review discusses the state of neurology and the Internet at the turn of the millennium. First, some basic definitions about the Internet and its component protocols are presented. Next, ways neurologists and patients can use the Internet are enumerated. Internet resources or applications are available or are being created that can aid in the successful fulfillment of a neurologist's core professional activities: clinical care, teaching, research, and practice issues. Currently, the most useful categories of Internet resources for neurologists are electronic communication and access to knowledge bases. They fulfill needs that are not met by traditional, non-electronic media. There are many other types of Internet applications that supplement traditional medical methodologies. Finally, some problems and prospects concerning medical uses of the Internet are discussed: technological infrastructure including usability, security, meaning, validity/quality, value, outcomes, and responsibility. These issues must be successfully addressed if Internet computing is to become truly useful 'just in time' at the point of medical care. Solutions are actively under development today. The prospects are bright for neurology, and medicine in general, on the Internet. The Internet will become an essential medical device in the near future.

Myofibrillar myopathy with abnormal foci of desmin positivity. I. Light and electron microscopy analysis of 10 cases.

A number of myopathies whose common denominator is abnormal foci of desmin positivity have been described under the rubrics of spheroid body myopathy, cytoplasmic body myopathy, Mallory body myopathy, myopathy with granulofilamentous inclusions, desmin storage myopathy, and intermediate filament myopathy. In this study we reevaluate the light microscopic and ultrastructural features of the myopathy with abnormal foci of desmin positivity. In 10 cases of the disease, ultrastructural analysis reveals 2 major types of lesions: (a) foci of myofibrillar destruction and (b) hyaline structures that appear as spheroidal bodies on electron microscopy. The foci of myofibrillar destruction consist of fiber areas containing disrupted myofilaments, Z-disk-derived bodies, dappled dense structures of Z-disk origin, and streaming Z-disks that are sometimes adjacent to lakes of dense material. The spheroid bodies are composed of compacted and degraded myofibrillar elements. Membrane-bound vacuoles harboring degenerating membranous organelles are a less frequent and probably secondary abnormality. None of the lesions in muscle comprise 8 to 10 nm intermediate filaments. The findings imply that spheroid body myopathy, cytoplasmic body myopathy, Mallory body myopathy, and myopathy with granulofilamentous inclusions are consequences of a single or closely related pathologic processes. Because the common denominator appears to be focal dissolution of the myofibrils followed by accumulation of the products of the degradative process, we propose the term myofibrillar myopathy to cover the observed spectrum of pathologic changes.

Neurological manifestations of acute posterior multifocal placoid pigment epitheliopathy.

BACKGROUND: Acute posterior multifocal placoid pigment epitheliopathy (APMPPE) is a chorioretinal disease that causes acute visual symptoms with characteristic fundus findings. Although this entity has been associated with a variety of neurological complications, it has received little attention in the neurological literature. We wanted to emphasize the spectrum of neurological involvement, in particular the occurrence and management of strokes in patients with APMPPE. CASE DESCRIPTIONS: We report three patients with APMPPE and neurological disease. All three presented with marked visual disturbances and headaches. One patient developed recurrent strokes involving different vascular territories of the brain and required immunosuppressive treatment for presumed cerebral vasculitis. The other two patients had cerebrospinal fluid pleocytosis and persistent headaches but recovered spontaneously. The review of the literature demonstrates a particular pattern of neurological complications in a subgroup of patients with APMPPE. CONCLUSIONS: APMPPE should be considered among the causes of stroke and aseptic meningitis in young adults. The diagnosis is critically dependent on a thorough ophthalmologic examination. Severe neurological complications are difficult to predict at the onset of the ophthalmologic disease. The patients should be monitored closely. If investigations suggest cerebral vasculitis, immunosuppressive treatment may be helpful to prevent recurrences.

Stretch-induced spinal accessory nerve palsy.

Left spinal accessory nerve palsy occurred in a young man when he quickly turned his head to the right while his shoulders were pulled down by heavy hand-held objects. Electrophysiologic studies demonstrated partial axonotmesis of the spinal accessory nerve branches innervating the sternocleidomastoid and upper and middle trapezius and complete axonotmesis of spinal accessory branches to the lower trapezius. There was a separate, although functionally minor, cervical plexus innervation of the lower trapezius.

Lumbrical sparing in carpal tunnel syndrome: anatomic, physiologic, and diagnostic implications.

Motor axons supplying lumbrical muscles are less severely affected than axons supplying thenar muscles in the carpal tunnel syndrome; sometimes lumbrical motor fibers are less affected than digit 2 sensory fibers. This pattern is consistent with compression of both the anterior and posterior aspects of the median nerve in the carpal tunnel because nerve fibers responsible for thenar, lumbrical, and digit 2 functions lie in an anterior-posterior gradient within the distal median nerve. Recognition of lumbrical sparing supports the electrodiagnosis of carpal tunnel syndrome when the distal latency to thenar muscles or the palm-to-wrist mixed median nerve conduction velocity is normal.

Cervical root stimulation in the diagnosis of radiculopathy.

Cervical root stimulation (CRS) was compared with conventional EMG, nerve conduction, and late response studies in 34 patients with possible cervical radiculopathy. Cervical roots were stimulated by monopolar needles inserted into paraspinal muscles, recording compound muscle action potentials in biceps, triceps, and abductor digiti minimi muscles. In 18 patients with clinical evidence of radiculopathy, EMG was abnormal in 11 (61%), but CRS was abnormal in all 18. Of 16 patients with symptoms but no signs of radiculopathy, EMG was abnormal in 5 (31%) and CRS was abnormal in 9 (56%).

Electrophysiologic assessment of a median nerve injury in the palm.

In median nerve lesions of the hand, electrophysiologic evaluation of the second lumbrical muscle can help to differentiate between lesions of the common digital nerves and the proper digital nerves, as illustrated by this case report. Median nerve conduction studies to the second lumbrical muscle can be performed by placing an active recording electrode just radial to the midpoint of the third metacarpal and stimulating the median nerve at the wrist or elbow.

A discrete lesion of ventral hypothalamus and optic chiasm that disturbed the daily temperature rhythm.

A patient with a discrete metastasis in the ventral hypothalamus and optic chiasm is reported, who developed an abnormal daily rhythm of oral temperature without alteration of the 24-h mean temperature. This region, its afferents, and its efferents appear to be important in the neural regulation of human circadian rhythmicity.

Periodic leg movements of sleep (nocturnal myoclonus): an electrophysiological study.

Six patients with periodic leg movements of sleep (PLMS) were studied electrophysiologically. All patients had normal results on routine nerve conduction studies and electromyography. In 5 patients the blink reflex consisted of three components, and in 1 patient it consisted of four components, with two components being normal. The second component of their blink reflex did not habituate. Other abnormalities included long-latency responses in the extremities in 2 patients, release of H-reflexes from flexor hallucis brevis muscle in 2 patients, and an Hmax/Mmax ratio of 98% in 2 patients. One patient's median nerve somatosensory-evoked response had a markedly enlarged P22 wave. These electrophysiological abnormalities suggest a disorder of the central nervous system producing increased excitability of segmental reflexes. To produce increased excitability of both brainstem and spinal cord reflexes, the disorder must be operative at the pontine level or rostral to it. Since long-latency components of blink reflexes occurred in all our patients, this may be a helpful diagnostic test when PLMS is suspected.

Familial syringomyelia.

A woman with syringobulbia and syringomyelia and her sister with syringomyelia are described. The diagnosis was confirmed radiologically and surgically in the first sister and no other definite abnormalities of her craniocervical junction were found.

Intraneuronal accumulation of myeloma proteins.

We studied a patient with multiple myeloma who had immunologically identified myeloma light chain proteins within neurons projecting beyond the blood-brain barrier, but not within intrinsic neurons of the spinal cord, brain stem, and cerebral cortex. There was a possibility that these myeloma light chain proteins or their immunologically recognizable fragments were transported intra-axonally by human peripheral nerves. Myeloma light chain proteins were also identified within cerebellar Purkinje's neurons. This labeling may have been secondary to transport from cerebrospinal fluid.

Peripheral neuropathy, high serum IgM, and paraproteinemia in mother and son.

A mother and son had peripheral neuropathy, abnormal elevation of serum IgM, and paraproteinemia. These patients may have a familial disorder of immune regulation with antibody-mediated neuropathy or a familial neuropathy with a secondary immune response.

Three cholinergic neuroblastoma hybrid cell lines that form few synapses on myotubes are deficient in acetylcholine receptor aggregation molecules and large dense core vesicles.

Three neuroblastoma X glioma hybrid cell lines that synthesize and release acetylcholine but that form few or no synapses with cultured skeletal muscle cells lack two characteristics of neuroblastoma or hybrid cell lines that do form many synapses with myotubes: large dense core vesicles and the ability to increase the number of nicotinic acetylcholine receptor clusters on co-cultured myotube membranes. Functional synapse formation on myotubes was increased by co-culturing myotubes and cells from one of the defective lines with neuroblastoma cells that induce myotube acetylcholine receptor aggregation but which synthesize little or no acetylcholine.

Long-lasting synaptic potentials and the modulation of synaptic transmission.

Long-lasting postsynaptic potentials (PSPs) generated by decreases in membrane conductance (permeability) have been reported in many types of neurons. We investigated the possible role of such long-lasting decreases in membrane conductance in the modulation of synaptic transmission in the sympathetic ganglion of the bullfrog. The molecular basis by which such conductance-decrease PSPs are generated was also investigated. Synaptic activation of muscarinic cholinergic receptors on these sympathetic neurons results in the generation of a slow EPSP (excitatory postsynaptic potential), which is accompanied by a decrease in membrane conductance. We found that the conventional "fast" EPSPs were increased in amplitude and duration during the iontophoretic application of methacholine, which activates the muscarinic postsynaptic receptors. A similar result was obtained when a noncholinergic conductance-decrease PSP--the late-slow EPSP--was elicited by stimulation of a separate synaptic pathway. The enhancement of fast EPSP amplitude increased the probability of postsynaptic action potential generation, thus increasing the efficacy of impulse transmission across the synapse. Stimulation of one synaptic pathway is therefore capable of increasing the efficacy of synaptic transmission in a second synaptic pathway by a postsynaptic mechanism. Furthermore, this enhancement of synaptic efficacy is long-lasting by virtue of the long duration of the slow PSP. Biochemical and electrophysiological techniques were used to investigate whether cyclic nucleotides are intracellular second messengers mediating the membrane permeability changes underlying slow-PSP generation. Stimulation of the synaptic inputs, which lead to the generation of the slow-PSPs, increased the ganglionic content of both cyclic AMP and cyclic GMP. However, electrophysiological analysis of the actions of these cyclic nucleotides and the actions of agents that affect their metabolism does not provide support for such a second messenger role for either cyclic nucleotide.

Synaptic potentials in sympathetic ganglia: are they mediated by cyclic nucleotides?

The hypothesis that cyclic nucleotides are intracellular second messengers mediating the generation of synaptic potentials was studied in the sympathetic ganglia of the bullfrog. Synaptic potentials and the effect of administering cyclic nucleotides and agents which affect cyclic nucleotide metabolism were recorded by the sucrose gap technique. The administration of adenosine 3',5'-monophosphate (cyclic AMP), guanosine 3',5'-monophosphate (cyclic GMP), or several of their derivatives produced little or no change in membrane potential. Prostaglandin E1 did not block the generation of postsynaptic potentials. Theophylline produced membrane effects that were different from those associated with postsynaptic potential generation; it also reduced the slow excitatory postsynaptic potential (EPSP) and potentiated the slow inhibitory postsynaptic potential (IPSP). The administration of papaverine, however, reduced both the slow EPSP and the slow IPSP. Although synaptic stimulation increases both cyclic GMP and cyclic AMP in these neurons, these results raise the possibility that these cyclic nucleotides may have functionla roles other than mediation of synaptic potentials.