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The pathogenesis of sporadic amyotrophic lateral sclerosis (ALS) remains unknown. Neurophysiological studies provide evidence of hyperexcitability of the motor cortex or of impairment of inhibitory intrahemispheric modulation of the corticomotoneuron in ALS. In this paper, we used TMS to elicit transcallosal inhibition of the motor cortex in ALS patients in order to investigate whether interhemispheric inhibitory mechanisms subserved by callosal fibres are also disturbed in ALS. Twenty-five patients with ALS and 18 controls were recruited for the study. Resting Motor Threshold (RMT), Silent Period (SP) and interhemispheric inhibition (IHI) were recorded. No significant difference was detected regarding RMT or the duration of SP between patients and controls. IHI was detected in all controls. IHI was totally absent in eight patients, in another eight patients IHI did not reach a significant level and in the remaining nine patients was normal. The degree of IHI was significantly lower in ALS patients than in controls (p = 0.001). In conclusion, altered IHI in ALS patients is in line with the general pattern of reduced corticomotoneuron inhibition, being thus, one of the factors which may lead to chronic overexcitation of pyramidal cells. [ABSTRACT FROM AUTHOR]

Owing to the variety of its clinical presentations, amyotrophic lateral sclerosis (ALS) may mimic several neurological syndromes and even lead to inappropriate surgical procedures. We wished to assess the impact of unnecessary surgical treatments among ALS patients, and therefore we retrospectively reviewed medical records of 164 consecutive ALS patients. We collected data on the clinical presentation of ALS at onset, the initial symptom that led the patients to seek medical care, the timing of diagnosis and surgical procedures attributed to the onset of symptoms. Results showed that among 164 consecutive patients with ALS, 13 (7.9%) were surgically treated as a consequence of false diagnosis. Despite this, these patients showed no statistically significant difference in time of diagnosis compared to non-operated patients. In conclusion, a small but not negligible number of ALS patients are misdiagnosed. The diagnostic pathway of these patients includes often specialists other than neurologists who should be more aware of this disease in order to avoid inappropriate surgical treatments and provide the patients the appropriate diagnostic and therapeutic procedure by referring them promptly to a neurologist. [ABSTRACT FROM AUTHOR]

In spite of the diagnostic importance of the early phase of the sensory nerve action potential (SNAP), reliable electrodiagnostic metrics for this part of the recorded waveform are lacking. The average rise slope of the SNAP appreciates the steepness of the initial negative deflection of the waveform, which might be a useful metric for the first part of the potential. Sural nerve sensory neurography was performed in patients with various axonal neuropathies, and median nerve sensory studies were carried out in patients with carpal tunnel syndrome. Age-matched healthy individuals served as controls. The rise slope was compared to conventional SNAP parameters such as conduction velocity, latency, duration, and rise time. Overall, 537 sensory studies were prospectively analyzed. The rise slope of the sural SNAP demonstrated superior classification performance in terms of sensitivity (92.5%), specificity (97%), and area under the receiver operating characteristic curve (0.986), as compared to conventional SNAP parameters. Its diagnostic power was similarly excellent in median nerve studies, whereas here a slightly better classification performance was obtained by SNAP latency and conduction velocity. The average rise slope appears to do justice to the tight interplay between amplitude and rise time of the initial negative spike deflection, outperforming many conventional measures. This composite metric proved high diagnostic potency in particular with regard to axonal sensory nerve dysfunction. [ABSTRACT FROM AUTHOR]