Somatosensory evoked potentials in motor neuron disease

We studied median somatosensory evoked potentials (SEPs) in an unselected series of 30 patients with sporadic motor neuron disease (MND). SEPs were affected in 17 patients (57%), with a higher incidence of abnormality in amyotrophic lateral sclerosis and bulbar palsy than in progressive muscular atrophy. In a majority of patients, simultaneous bilateral stimulation of the median nerve revealed a delay or absence of scalp-recorded central N32 and/or N60, leaving the earlier peaks intact. In the remaining cases, the N19 peak was asymmetrically prolonged. These findings suggest common involvement of somatosensory pathways in MND, either at cortical or subcortical levels, and correlate with neuropathologic reports of neuronal degeneration beyond the primary motor system.     

Far-field and cortical somatosensory evoked potentials in motor neuron disease

We examined median somatosensory evoked potentials (SEPs) in 26 patients with sporadic motor neuron disease (MND). SEPs were recorded with multiple scalp derivations, using both the midfront and the earlobe as references for each subject. Central conduction time (CCT) was abnormal in three patients, but only when using the midfront reference. Moreover, an exclusive alteration of the early prerolandic potentials (absent or delayed P20 and/or P22) was noted using the earlobe reference in amyotrophic lateral sclerosis and in progressive bulbar palsy (54% and 50% of patients, respectively) but not in progressive muscular atrophy. These findings correlated with clinical evidence of upper motor neuron signs and with the severity of the disease. In agreement with recent views regarding the sources of the early anterior cortical responses, neuronal loss in the motor cortex may be considered as affecting the generator sites of these potentials.     

Multimodality evoked potentials in children with moyamoya disease

Twenty Japanese children with Moyamoya disease were investigated by examining the multimodality evoked potentials (BAEPs, FVEPs and SSEPs). BAEPs were abnormally prolonged wave I-III and wave III-V in each one (10%). FVEPs were abnormal in 6 (30%), included prolonged latencies, reduced amplitudes and poor waveform in one each, and delayed latencies as well as reduced amplitudes in three. FVEPs significantly correlated with intellectual deterioration (p less than 0.01). SSEPs were abnormal in 13 (65%) significantly more frequent than BAEPs and FVEPs (p less than 0.01); reduction of N20 in 7, delayed latencies of N13-N20 in 4, and both delayed latencies and reduced amplitudes of N20 in two. These findings correlated well with the neurologic deficits, CT findings and EEG findings in this progressive cerebrovascular disease (Moyamoya disease) in children.     

Multimodality evoked potentials in myotonic dystrophy

Multimodality evoked potentials were performed in 18 patients affected by myotonic dystrophy (8 males and 10 females); the aim was to make an electrophysiological evaluation of the central nervous system involvement in this disease. We observed brainstem, somatosensory and visual evoked potential abnormalities respectively in 53%, 62.5% and 71.4% of cases, with no apparent relationship to the severity of the disease. Our abnormal findings provide further confirmation of CNS involvement in myotonic dystrophy and occur in various combinations suggesting an aspecific involvement at different levels, reflecting the multisystemic character of this disease.

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Sommario I potenziali evocati multimodali sono stati effettuati in 18 pazienti (8 maschi e 10 femmine), affetti da distrofia miotonica. Lo scopo era di effettuare una valutazione elettrofisiologica dell'interessamento del sistema nervoso centrale in questa malattia. I potenziali evocati del tronco, somatosensitivi e visivi sono risultati abnormi rispettivamente nel 53%, 62.5% e 71.4% dei casi, senza apparente relazione con la gravità della malattia. I risultati da noi ottenuti forniscono un'ulteriore conferma dell'interessamento del SNC nella distrofia miotonica che è possibile in varie combinazioni, suggerendo un aspecifico interessamento a diversi livelli, che riflette il carattere multisistemico della malattia.

     

Multimodality evoked potentials in closed head trauma

Patients with closed head injuries who had Glasgow coma scale scores of 7 or less were studied with evoked potentials soon after trauma. Of the patients, 39 had brain-stem auditory evoked potentials (BAEPs); 12, stroboscopic visual evoked potentials (VEPs); and 23, short-latency somatosensory evoked potentials (SSEPs). Evoked potential results were graded from 1 (normal) to 4 (most abnormal). Outcomes were categorized by the Glasgow outcome scale, with good outcome and moderate disability further classified as "favorable" and severe disability, vegetative state, and death as "unfavorable." The BAEPs and VEPs were reliable predictors of an unfavorable but not a favorable outcome. The SSEPs reliably predicted both kinds of outcomes. No instances of "false pessimism" were encountered in any modality. Evoked potential results were more reliable than intracranial pressure, pupillary light reaction, or motor findings in predicting outcome. Frequent occurrence of peripheral auditory injuries was shown.     

Multimodality evoked potentials in amyotrophic lateral sclerosis

Visual, brainstem auditory and somatosensory evoked potentials to medial nerve stimulation were recorded in 27 patients affected by amyotrophic lateral sclerosis. VEP N75, P100, N140, N75-P100 latencies and P100 amplitude, BAEP I-III, III-V and I-V interpeak-latencies were within normal limits in all ALS patients. Somatosensory evoked potentials were abnormally delayed in 8 patients: in 3 arms because of a delayed N9-N13 latency, in 9 arms because of a delayed N13-N19 latency.     

Multimodality evoked potentials in HTLV-I associated myelopathy.

Multimodality evoked potentials (EPs) consisting of somatosensory EPs (SEPs), visual EPs (VEPs) and brainstem auditory EPs (BAEPs) were studied in 16 cases with HTLV-I associated myelopathy (HAM). Median nerve SEPs were normal in all cases. In posterior tibial nerve SEPs, the potential recorded at the 12th thoracic spinal process was normal in every case but cortical components were significantly prolonged in 10 cases, although five of these showed no sensory impairment. BAEPs were normal in every case whose hearing was intact, but VEPs were abnormal in two cases whose visual acuities were normal. The present results in HAM indicate predominant lesion in the thoracic cord, and might also suggest some subclinical lesion in the visual pathway.     

Multimodality evoked potentials in progression of metachromatic leukodystrophy

A 2-yr-3-mo-old girl with metachromatic leukodystrophy (MLD) was examined using serial multiple electrophysiological procedures. Sensory nerve conduction velocity was delayed earlier and more severely than motor nerve conduction velocity. Visual evoked potentials (VEPs) showed prolonged latency of wave IV. Auditory brainstem responses (ABRs) showed prolonged latency of waves I and V, and the I-V interval. As to the interpeak latency of somatosensory evoked potentials (SEPs), the P9-P14 and the P14-N20 intervals were prolonged on admission. Two months later, both intervals were more prolonged, but the prolongation of the P9-P14 interval was the most prominent. The demyelination in our case may have started in the cerebral white matter, progressed to the peripheral nerves, and at last via the spinal root reached the brainstem. An electrophysiological follow-up study may be valuable in the understanding of the progressive pathological changes and in the evaluation of therapeutic measures.     

Identifying fasciculation potentials in motor neuron disease: A matter of probability

Introduction: Fasciculations, the spontaneous activity of single motor units (MUs) are characteristic, but nonspecific for motor neuron disease (MND). We aimed to identify MU discharge properties to optimally differentiate MND patients from healthy controls. Methods: High‐density surface electromyography recordings were performed in the thenar muscles during 10 min of rest. MU discharges were classified as “isolated” when the interspike intervals (ISIs) before and after were > 250 ms, “continual” when both ISIs were ≤ 250 ms, or as “other”. Results: In patients (n = 30) compared with controls (n = 14), more MUs were active (9 vs. 3, P < 0.001) and generated relatively more isolated discharges (35% vs. 10%, P = 0.01). Two or more MUs with isolated discharges occurred more frequently in patients compared with controls (24% vs. <1% of 10‐s windows, P < 0.001). Conclusions: More frequent occurrence of multiple MUs showing isolated discharges may improve identification of patients with MND. Muscle Nerve 53: 227–233, 2016     

Motor evoked potentials in Wilson's disease: early and late motor responses

Motor evoked potentials following magnetic stimulation of the motor cortex and the spinal roots were studied in 13 patients with Wilson's disease (WD). The fast-conducting motor pathway function was normal in 9 patients. The cortically-evoked motor responses were absent in patients with cerebral white matter lesion and akinetic rigid syndrome. In addition to the primary or early motor response, late motor response was common in WD and occurred with a latency of 70-90 msec for the upper limb and 90-110 msec for the lower limb. The cause of the late motor response is unknown, but may be an enhanced late response infrequently observed in normal subjects.     

Multimodality evoked potentials in HIV infected subjects: A longitudinal study

18 subjects with symptomless HIV infection were investigated with multimodal evoked potentials for possible CNS involvement and again after an 8–12 month interval. 13 subjects showed neuropsychological changes, which were confirmed at the second examination. The 5 subjects found normal remained so at the second examination. On WAIS assessment the only patient to earn pathological scores was the one with the greatest evoked potentials changes. Thus the evoked potentials procedure proved capable of identifying early CNS involvement by HIV infection.

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Sommario Diciotto soggetti affetti da infezione da HIV in fase asintomatica sono stati studiati con Potenziali Evocati Multimodali per indagare l'eventuale coinvolgimento del S.N.C. Lo studio è stato ripetuto a 8–12 mesi di distanza. In 13 soggetti sono state evidenziate alterazioni neuropsicologiche confermate dal successivo controllo. I 5 soggetti risultati normali alla I registrazione si sono conservati tali alla registrazione successiva. I pazienti sono stati valutati anche con la WAIS. L'unico soggetto che ha presentato punteggi patologici era quello con maggiori alterazioni dei potenziali evocati. La metodica dei potenziali evocati si è mostrata capace di individuare il precoce interessamento del S.N.C. nell'infezione da HIV.

     

Multimodality evoked potentials in patients and carriers with adrenoleukodystrophy and adrenomyeloneuropathy

A combination of brain-stem auditory evoked potentials (BAEPs), short latency somatosensory evoked potentials (SEPs) and pattern reversal visual evoked potentials (VEPs), were studied in two patients with adrenoleukodystrophy (ALD) and one patient with adrenomyeloneuropathy (AMN), as well as in one female carrier of each of the respective diseases. Abnormalities in at least 1 of the 3 evoked potentials were found in every case, including the carriers of ALD and AMN. The two most common findings were prolongation of the I-V interval of the BAEP and the N13-N20 interval of the SEP. These abnormalities were recorded either alone or in combination in all 5 cases. This finding suggests delayed conduction time in the central sensory pathways in both diseases, probably due to demyelination. The remarkable result, which distinguished AMN from ALD, even in their respective carriers, was delay of the N9 latency of the SEP, indicating slowing in conduction velocity of the peripheral nerve. Multimodality evoked potentials are useful not only in raising the detection rate for abnormal findings, but also in providing additional information about the functional state of separate afferent pathways. It is also of value in detecting and differentiating the carriers of ALD and AMN.     

Multimodality evoked potentials and electrically elicited blink reflex in optic neuritis

Summary Pattern shift visual evoked potentials, brain stem auditory evoked potentials, spinal and scalp recorded somatosensory evoked potentials, and electrically elicited blink reflexes were investigated in 32 patients with isolated optic neuritis. Eleven patients were shown to have one additional lesion in the central nervous system outside the optic nerve. Therefore, cases with optic neuritis of unknown origin should be considered as possible cases of multiple sclerosis.

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Zusammenfassung Visuelle, durch Musterumkehr evozierte Potentiale, akustisch evozierte Hirnstammpotentiale, somatosensorisch evozierte Potentiale mit Ableitung über dem unteren Cervicalmark und über dem kontralateralen Handfeld sowie elektrisch ausgelöste Blinkreflexe wurden bei 32 Patienten mit einer isolierten Opticusneuritis untersucht.Bei 11 Patienten konnten mit Hilfe dieser elektrophysiologischen Untersuchungen eine oder mehrere, weitere Läsionen im Bereich des Zentralnervensystems nachgewiesen werden. Es wird vorgeschlagen, Fälle mit einer isolierten Opticusneuritis unklarer Ursache deshalb in die Kategorie mögliche MS einzureihen.

     

Central motor conduction in motor neuron disease

Central motor conduction was assessed in 13 patients with motor neuron disease and in 15 control subjects. All patients with motor neuron disease, even those without clinical pyramidal signs, had slowed central motor conduction, and in some the delays were asymmetrical. Evoked motor potentials represent a new and reliable method to detect physiological abnormalities of central motor pathways early in the course of motor neuron disease.     

Flaviviruses in motor neuron disease

Sporadic motor neuron disease (MND) causes a progressive loss of motor neurons. West Nile virus can attack motor neurons, so we examined whether flavivirus infection could be detected in MND cases. Spinal cord sections from 22 MND cases were stained immunohistochemically with a flavivirus-specific antibody. No staining for flavivirus was seen in any case. Sporadic MND does not appear to arise from a recent infection with a flavivirus.     

A comparison of somatosensory evoked and motor evoked potentials in stroke

Nineteen patients with radiologically confirmed stroke, and varying degrees of hemiparesis, were studied using somatosensory evoked potentials and the recently developed technique of transcutaneous motor cortex stimulation. The functional deficit caused by stroke was assessed at the time of evoked potential testing and again on follow-up 2 months after stroke. Stroke location and degree of recovery were compared with the evoked potentials elicited an average of 8 days after the acute event. The motor response was better (p less than 0.01) than somatosensory response at predicting an outcome in terms of functional recovery, both overall and when comparing patients with similar degrees of weakness. Normal somatosensory evoked potentials also predicted recovery but were not as sensitive as the motor evoked potentials (0.01 less than p less than 0.05). Motor evoked potentials in conjunction with clinical assessment may offer a means of more accurately predicting functional outcome following stroke than can be achieved with clinical assessment, with or without somatosensory evoked potentials. The additional finding that cortically evoked motor evoked potentials were delayed only by subcortical lesions is of interest and may extend the understanding of the pathophysiological mechanism of this response in humans.