Assessing diaphragmatic contractility is a common goal in various situations. This assessment is mainly based on static or dynamic maximal voluntary maneuvers and twitch transdiaphragmatic pressures (Pdi) obtained by stimulation of the phrenic nerves (PS). PS eliminates the central components of diaphragmatic activation, but the available techniques of PS remain subject to some limitations. Transcutaneous PS is painful, and needle PS is potentially dangerous. Time-varying magnetic fields can stimulate nervous structures without pain and without adverse effects. In six subjects, we have studied cervical magnetic stimulation (CMS) as a method of PS. We have compared the stimulated Pdi (Pdistim) with the maximal Pdi obtained during static combined expulsive-Mueller maneuver (Pdimax) and with the Pdi generated during a sniff test (Pdisniff). CMS produced twitch Pdi averaging 33.4 +/- 9.7 cmH2O. Pdistim/Pdimax and Pdistim/Pdisniff were 24 +/- 6 and 41 +/- 14%, respectively. These values are comparable to those obtained in other studies with transcutaneous PS. They were highly reproducible in all the subjects. Electromyographic data provided evidence of bilateral maximal stimulation. CMS is a nonspecific method and may stimulate various nervous structures. However, diaphragmatic contraction was elicited by stimulation of the phrenic trunk, since the phrenicodiaphragmatic latencies (less than 7 ms) were in the range of values reported with direct stimulation of the trunk. Cocontraction of neck muscles, including the sternomastoid, was present, but its influence in the CMS-induced Pdi seems minimal. We conclude that magnetic stimulation is an easy, well-tolerated, reproducible safe, and valuable method to assess phrenic conduction and diaphragmatic twitch response.

Clinical and electrophysiologic data recorded in patients with Fisher syndrome characterized by ophthalmoplegia, ataxia, and areflexia are presented. Cases with limb weakness or pleocytosis in the CSF were excluded, according to Fisher. Ten patients were selected. All had hand and foot numbness. A large amount of protein without cell reaction was found during the third week of illness in serial CSF examinations. EMGs showed very slight limb involvement without spontaneous activity, and in most cases, facial muscles exhibited a denervation pattern. Distal motor nerve conduction velocity on limbs and F wave latencies were normal, whereas the sensory nerve action potentials were altered in all but one case when tested (seven out of eight cases). By means of blink reflex study performed in four patients, no significant pattern of brainstem dysfunction was discovered. The authors discuss the preeminent role of peripheral nerve lesions with regard to the ataxia and ophthalmoplegia.

SUMMARY Twenty five patients with peripheral neuropathy at different stages of human immunodeficiency virus (HIV) infection are reported. Cerebrospinal fluid (CSF) findings were available in 17 cases, electrophysiology in all and a neuromuscular biopsy in 11. Of six otherwise asymptomatic HIV + patients, five had chronic inflammatory demyelinating polyneuropathy (CIDP) and one acute inflammatory demyelinating polyneuropathy (AIDP). CSF showed pleocytosis in all cases. Infiltration of the endoneurium and/or the epineurium by mononuclear cells was seen in biopsies from three cases. These six patients recovered either spontaneously, or with corticosteroids or plasmaphereses. Of five patients with AIDS related complex (ARC), three had distal predominantly sensory peripheral neuropathy(DSPN), one CIDP and one mixed neuropathy. Of 14 patients with AIDS, one had mononeuropathy multiplex and 13 painful DSPN. Electrophysiological studies were consistent with an axonopathy. Nerve biopsies in six cases showed axonal changes but surprisingly associated with marked segmental demyelination in two cases. Cell infiltration was present in nerve samples in two cases. Five patients died within six months after the onset of the neuropathy.

Twenty-two patients with evidence of systemic vasculitis and peripheral neuropathy were clinically and electrophysiologically investigated in a retrospective study. Ten had a polyarteritis nodosa, 6 a probable polyarteritis nodosa, and 6 a Churg-Strauss syndrome. Nine patients presented clinically with mononeuropathy or mononeuropathy multiplex considered typical of ischemic involvement of peripheral nerve; nine had more diffuse neuropathy, two of them a symmetric polyneuropathy. EMG examination revealed more diffuse neuropathy than clinically predicted. Findings were of acute or subacute axonal neuropathy.

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