THE VESTIBULAR SYSTEM IN MULTIPLE SCLEROSIS. A CLINICAL-HISTOPATHOLOGICAL STUDY

Wave I of early auditory evoked potentials in multiple sclerosis

Early auditory evoked potentials (EAEPs) were recorded in a series of 71 consecutively examined patients suffering from clinically definite or probable multiple sclerosis (MS). Wave I abnormalities, i.e., delayed latency, with or without reduced amplitude, were observed in 15 such patients and were interpreted as due to MS in 8 of them. As EAEP wave I is identical with the potential N1 in electrocochleography and corresponds to activity of the most distal part of the acoustic nerve or the spiral ganglion, it is concluded that the peripheral part of the acoustic nerve is involved in about 10% of MS patients. In two cases normalization of initially delayed wave I latencies were demonstrated during follow-up recording. The pattern of a late wave I but normal hearing in 3 patients is interpreted in terms of a desynchronized compound nerve activity with fully preserved conductivity, segmental demyelination of a considerable number of acoustic nerve fibres being the most likely cause.

Neurologic disorders: amyotrophic lateral sclerosis, myasthenia gravis, multiple sclerosis, and poliomyelitis

The patient who has multiple cranial neuropathies may pose a diagnostic dilemma. The neurologic disorders of amyotrophic lateral sclerosis, multiple sclerosis, myasthenia gravis, and poliomyelitis often cause bulbar dysfunctions such as diplopia, facial weakness, slurred or hypernasal speech, dysphagia, and hoarseness. In general, treatment is supportive and is directed toward restoring or aiding lost function (i.e., tracheostomy, esophagostomy, and cricopharyngeal myotomy). The relative infrequency of these disorders can lead to delays in diagnosis and rehabilitative therapy.

Multiple sclerosis associated with defects in neuromuscular transmission

Three patients with multiple sclerosis characterized by exacerbations and remissions of nervous system signs and symptoms disseminated in time and space also had the kind of easy fatiguability seen in myasthenia gravis. In each case abnormal decrements to repetitive stimulation were electromyographically demonstrated and treatment with ephedrine or anticholinesterase drugs increased the patient's functional capacity while improving the electromyographic abnormality. The suggestion is that these patients represent an overlap syndrome, analogous to the overlap syndrome existing between systemic lupus erythematosus and rheumatoid arthritis where clinical and laboratory features of two diseases coexist in the same patient at the same time. Presumably some patients with multiple sclerosis have deficient production of acetylcholine, just like patients with myasthenia, and treatment with agents useful in myasthenia is able partially to correct the symptoms caused by the deficiency. The cases illustrate how in neurology greater attention to the more immediate cause of clinical symptoms, in the absence of a known aetiology, may result in benefit to the patients.