Neurophysiological impairments in multiple sclerosis—Central and peripheral motor pathways

A systematic review of the literature was conducted comparing neurophysiological outcomes in persons with multiple sclerosis (PwMS) to healthy controls (HC), in studies of the central nervous system (CNS) function comprising motor evoked potentials (MEP) elicited by transcranial magnetic stimulation (TMS) and in studies of the peripheral nervous system (PNS) function comprising electroneuronography (ENG) outcomes elicited by peripheral nerve stimulation. Studies comparing neuromuscular function, assessed during maximal voluntary contraction (MVC) of muscle, were included if they reported muscle strength along with muscle activation by use of electromyography (EMG) and/or interpolated twitch technique (ITT). Studies investigating CNS function showed prolonged central motor conduction times, asymmetry of nerve conduction motor pathways, and prolonged latencies in PwMS when compared to HC. Resting motor threshold, amplitude, and cortical silent periods showed conflicting results. CNS findings generally correlated with disabilities. Studies of PNS function showed near significant prolongation in motor latency of the median nerve, reduced nerve conduction velocities in the tibial and peroneal nerves, and decreased compound muscle action potential amplitudes of the tibial nerve in PwMS. ENG findings did not correlate with clinical severity of disabilities. Studies of neuromuscular function showed lower voluntary muscle activation and increased central fatigue in PwMS, whereas EMG showed divergent muscle activation (ie, EMG amplitude) during MVC. When comparing the existing literature on neurophysiological motor examinations in PwMS and HC, consistent and substantial impairments of CNS function were seen in PwMS, whereas impairments of the PNS were less pronounced and inconsistent. In addition, impairments in muscle activation were observed in PwMS.     

Somatosensory evoked potentials in the evaluation of patients with stocking/glove paresthesias

We studied 10 patients referred for suspicion of peripheral neuropathy. They all complained of paresthesias with a stocking distribution. As EMG, motor and sensory nerve conduction studies failed to confirm the clinical diagnosis, we studied somatosensory evoked potentials (SEP) following median and tibial nerve stimulation. The SEP findings were compared with controls and 10 spastic paraplegias. The evoked potential study revealed prolonged latencies of cortical potentials after tibial nerve stimulation in all the patients with paresthesias and were considered evidence of myelopathy.     

Electrophysiological study of neuromuscular function in a population poisoned by lead

A comprehensive electrophysiological examination of the peripheral nervous system was carried out in 12 patients who proved to be toxicated with lead (high lead blood levels, and diminished activity of the delta-aminolevulinate dehydratase, ALA D, in erythrocytes). Maximal motor nerve conduction velocities and terminal latencies were investigated in the median, radial and deep peroneal nerves. Also the amplitude of the evoked muscle response (M wave) was measured in thenar, extensor longus and extensor digitorium brevis muscles. Sensory conduction velocity and amplitude of the nerve compound action potential were measured at the median nerve. Tibialis anterior muscle responses to deep peroneal nerve repetitive stimulation were also explored. Conventional needle electromyogram was performed in the deltoid and tibialis anterior muscles. Slight diminished motor and sensory conduction velocities were found as well as a reduction of the amplitude of the evoked muscle response of the compound sensory action potential. Four out of the 12 patients tested showed either decremental or incremental amplitude of the muscle response with nerve repetitive stimulation. A electromyographical diminished interference pattern was found in all patients tested. Most of the remaining motor unit potentials were fragmented or polyphasic. Just one patient disclosed potentials of enhanced duration and amplitude. No relationship was found between blood lead levels or ALA D erythrocytes concentration and the different electrophysiological tests performed, except between reduced ALA D concentration and diminished amplitudes of the M wave and of the sensory compound action potential, and also between ALA D and diminished radial motor conduction velocity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Peripheral neuropathy in patients with beta-thalassaemia.

As some patients with beta-thalassaemia manifested neurological signs, clinical and electrophysiological investigations were carried out on 53 thalassaemic patients and 29 healthy control subjects. Twenty per cent of the patients showed clinical and electrophysiological findings of a mild peripheral sensorimotor neuropathy, mainly of the lower limbs. The clinical symptoms were numbness, pins and needles sensations, muscular cramps, myalgia and muscle weakness. The electrophysiological abnormalities were manifested by decreased motor conduction velocity (MCV) and prolonged F-wave latencies of the tibial and the peroneal nerves. Borderline increase in the latencies of the sensory potentials of the median nerve was also observed. The electromyographic findings of the patients with diminished MCVs were compatible with a predominantly motor peripheral neuropathy. This neuropathy appears during the second and third decade of life.     

Antiepileptic drug effects on somatosensory evoked potentials

Some evoked potential changes have been documented in chronic phenytoin (PHT), valproate (VPA), or benzodiazepine therapy, whereas other studies have suggested little change with carbamazepine (CBZ) or phenobarbital (PB). We recorded median and posterior tibial nerve somatosensory evoked potentials (SEPs) in complex partial seizure patients taking PHT, CBZ, or VPA in monotherapy with stable therapeutic serum levels and no toxic symptoms. Ten patients each were studied with PHT, CBZ, and VPA and were compared with age-matched controls. Median nerve responses were recorded at Erb's point, cervical spine, and contralateral cerebral sites; tibial nerve evoked potentials were recorded from popliteal fossa, lumbar, cervical spine, and midline scalp electrodes. Epileptic patients and controls did not differ in SEP latency, amplitude, or central condition time. PHT prolonged Erb's point and popliteal fossa latencies, but not central conduction time. CBZ had no effect on latencies or amplitudes. Evoked potential amplitudes were reduced by VPA, and cortical response latencies were minimally prolonged. Chronic antiepileptic therapy without toxicity had little effect on SEPs. PHT may have a slight effect on peripheral nerve conduction, and VPA may have an effect on amplitude of cerebral responses.     

多发性硬化周围神经病变的电生理评价

目的研究多发性硬化(MS)患者的周围神经病变，并评价神经电生理技术的应用价值。方法采用神经传导速度(NCV)技术检测MS患者周围神经的运动传导速度(MCV)、感觉传导速度(SCV)及其潜伏期；采用运动诱发电位(MEP)检测正中神经和胫神经的潜伏期；采用F波检测正中神经的出现率和传导速度。结果MS患者NCV均不同程度地减慢，MCV的异常率高于SCV，NCV结果提示轴突损害比脱髓鞘显著。MEP测得肘点和腰4点的潜伏期延长，提示正中神经远端和腰骶神经根功能的损害。部分患者F波的出现率降低．提示周围神经根功能异常。结论MS患者存在周围神经病变；综合运用电生理技术可以全面地评价MS周围神经功能。     

Evaluation of central neuropathy in type II diabetes mellitus by multimodal evoked potentials

The electrophysiological results in 51 patients with diabetes mellitus type II were compared with those in 30 age and sex matched healthy control subjects. Peripheral and cortical latencies of median and tibial somatosensory evoked potentials (SEP), bilateral I-III and I-V interpeak latencies (IPL) of brainstem auditory evoked potentials (BAEP), bilateral P100 latency of visual evoked potentials (VEP) and bilateral cortical latency and central motor conduction time of motor evoked potentials (MEP) were evaluated. We observed prolonged latencies suggestive of central neuropathy in DM type II. It has been shown that most of the electrophysiological parameters in patients with DM type II correlate with the duration of the disease, some of them with the age of the patient, and few of them with the onset of the disease. To our knowledge, there is no correlation between the electrophysiological parameters and the level of glycemia or the degree of metabolic control. We conclude that central and peripheral neuropathies in DM are related to the duration of the disease and not to the degree of hyperglycemia and metabolic control.     

Neurological complications of prolonged hunger strike

We investigated neurological findings in 41 prisoners (mean age: 28.6) who participated in a hunger strike between 2000 and 2002. All cases were evaluated using neuropsychological, neuroradiological, and electrophysiological methods. The total duration of fasting ranged from 130 to 324 days (mean 199 days). All cases had 200–600 mg/day thiamine orally for 60–294 days (mean 156) during the hunger strike, and had neurological findings consistent with Wernicke–Korsakoff syndrome. All 41 patients exhibited altered consciousness which lasted from 3 to 31 days. All patients also presented gaze-evoked horizontal nystagmus and truncal ataxia. Paralysis of lateral rectus muscles was found in 14. Amnesia was apparent in all cases. Abnormal nerve conduction study parameters were not found in the patient group, but the amplitude of compound muscle action potential of the median and fibular nerves and sensory nerve action potential amplitude of the sural nerve were lower than the control group, and distal motor latency of the posterior tibial nerve was significantly prolonged as compared with the control group. The latency of visual evoked potential was prolonged in 22 cases. Somatosensory evoked potential (P37) was prolonged but not statistically significant. Our most significant finding was that the effect of hunger was more prominent on the central nervous system than on the neuromuscular system, despite the fact that all patients were taking thiamine. In our opinion, partial recovery of neurological, and neurocognitive signs in prolonged hunger could be a result of permanent neurological injury.     

Painful Diabetic Neuropathy - A Therapeutic Challenge For The New Millennium

Clinical spectrum of diabetic neuropathy is variable; it may be asymptomatic, but once established, it becomes irreversible and disabling. Some investigators suggested that earliest change in diabetic nerve function is alteration in axonal excitability due to alterations in ion conductance of axon membrane, although these functional changes of ion channels necessarily cause permanent damage or degeneration of nerve fibers. Among various parameter of nerve conduction study in diabetics, prolonged F-wave latency in the peroneal and tibial nerve seems the commonest abnormality in asymptomatic patients. Decrease in amplitude of compound sensory action potential of sural nerve is another earlier abnormality, which is, then, accompanied by a fall in motor amplitude of peroneal and tibial nerves in advanced patients. In disabled patients no motor response is often elicited in the legs. Previous electrophysiological studies could not make clear if central axons were involved or not in diabetic neuropathy. Recently, our group has demonstrated that somatosensory central conduction from the spinal cord to the sensory cortex is delayed in diabetics as well as in the peripheral conduction, which might be partly responsible for the irreversible clinical presentation of diabetic neuropathy.     

Neurological multisystem manifestation in multiple symmetric lipomatosis: A clinical and electrophysiological study

Multiple symmetric lipomatosis (MSL) is characterized by a typical neck and shoulder distribution of subcutaneous lipomata and is often associated with polyneuropathy. Occasionally, the central nervous system (CNS) can be involved. Twelve of 14 patients in this retrospective study had clinical or electrophysiological evidence of a predominantly axonal polyneuropathy. Among those were 10 with alcohol abuse, but 2 patients without alcohol abuse also showed clinical or electrophysiological polyneuropathy. Clinical CNS involvement was present in 4 patients. CNS dysfunction was documented by evoked potentials in 8 subjects [prolonged latency or low amplitude of the motor response following cortical magnetic stimulation (4 patients), abnormal visually evoked potentials (4 patients) or somatosensory evoked potentials (SEP) (4 patients)]. These findings were compared to 10 chronic alcoholics without clinical signs of MSL. Five of these showed mild sensory neuropathy. Additionally, 2 also had delayed SEP latencies. Motor evoked potentials were normal in all controls. We propose that the multisystem involvement in MSL demonstrated here cannot be attributed to alcohol abuse alone. Biochemical studies have suggested mitochondrial dysfunction as the basis of the widespread neurological pathology in MSL. © 1995 John Wiley & Sons, Inc.     

Subclinical lesions of peripheral nervous system in multiple sclerosis patients

BACKGROUND AND PURPOSE: In the last years the presence of peripheral nervous system (PNS) lesions has been noted in patients with multiple sclerosis (MS). The frequency and degree of PNS damage reported by many authors differ among publications, so does the type of PNS lesions. The aim of our study was to perform an electrophysiological evaluation of the peripheral nervous system in patients with a definite diagnosis of multiple sclerosis and without any clinical signs of peripheral neuropathy. MATERIAL AND METHODS: 110 patients were included in the study, comprising 70 people with a definite diagnosis of multiple sclerosis and 40 people without any symptoms of organic nervous system lesion serving as a control group. During neurologic examination of MS patients the degree of disability measured by EDSS scale, the duration of the disease as well as number of relapses were assessed. A "disease progression factor" was calculated by dividing a number of relapses by disease duration in years. Patients with common etiologies for peripheral neuropathy such as diabetes, renal insufficiency, thyroid gland dysfunction, proliferative disorders etc. were excluded from the study. Orthodromic motor conduction and late responses (F wave) in median, ulnar, peroneal and tibial nerves as well as sensory conduction in median, ulnar (orthodromic) and sural (antidromic) nerves were evaluated. RESULTS: There was electrophysiological evidence of peripheral nervous system lesions in at least one nerve in 52 (74.2%) MS patients. In 30 patients (42.8%) more than one peripheral nerve was lesioned. There were more significant differences noted during the examination of sensory nerves. Sensory amplitudes in all of the sensory nerves examined were significantly lower than in control group. Furthermore we observed slow sensory conduction velocities and prolonged sensory latencies in ulnar and sural nerves. There were significant differences between the two groups of patients concerning motor conduction too: prolonged distal latency in tibial and sural nerves, prolonged F wave latency in median, peroneal and tibial nerves, low motor amplitude in ulnar and peroneal nerves, low motor conduction velocity in ulnar nerve -- all noted in MS patients. We found no correlation between conduction parameters and the patients' age, disease duration, number of relapses and disease progression degree. CONCLUSIONS: We found out that subclinical peripheral nervous system abnormalities are very frequent in MS patients. We noted both sensory and motor nerve lesions of a demyelinating-axonal character. Sensory abnormalities were more pronounced than motor ones. There was no correlation between the degree of PNS lesions and the patients' age and/or progression of multiple sclerosis.     

Evoked potentials in HIV infection]

The study of the literature data on the multimodal evoked potentials in HIV infected patients shows many abnormalities as well in asymptomatic subjects without AIDS as in AIDS subjects with or without neurological signs. Visual evoked potentials (VEPs) reveal prolonged P100 wave latency in 22% of HIV asymptomatic subjects and in 26% of HIV symptomatic subjects; brainstem auditory evoked potentials (BAEPs) reveal an increase of the interpeak latency I-V in 16% of asymptomatic subjects and in 32% of symptomatic subjects; somatosensory evoked potentials (SEPs) by median nerve stimulation reveal prolonged central conduction time in 6% of asymptomatic subjects and in 11% of symptomatic subjects; somatosensory evoked potentials (SEPs) by tibial nerve stimulation reveal prolonged central conduction time in 4% of asymptomatic subjects and in 45% of symptomatic subjects; motor evoked potentials (MEPs) by magnetic stimulation reveal prolonged central motor conduction time in 46% of asymptomatic subjects.     

腓骨肌萎缩症2F型1家系临床分析

目的探讨腓骨肌萎缩症(CMT)2F型的临床特点。方法对1家系内3例患者的临床表现和神经电生理资料进行回顾性分析。结果该家系为晚发(37~60岁),感觉障碍轻,1例伴右侧听力下降;神经传导速度检查示下肢感觉和运动传导速度减慢,甚至引不出反应波,但上肢正常或接近正常;躯体感觉诱发电位示中枢神经和周围神经均受累,运动诱发电位示运动通路周围段传导减慢,脑干听觉诱发电位示一侧听通路周围段严重受累。结论CMT2F型患者的临床特征有助于CMT患者的诊断和分型。     

Electrophysiological studies in cerebrotendinous xanthomatosis.

Seven patients with cerebrotendinous xanthomatosis (CTX) were studied by electrophysiological techniques. The percentages of abnormalities detected in nerve conduction studies and electroencephalograms were 28.6% (two patients) and 100%, respectively. All patients showed prolonged central conduction times in short latency somatosensory evoked potentials (SSEPs) by tibial nerve stimulation but normal SSEPs by median nerve stimulation. Brain stem auditory evoked potentials and visual evoked potentials were abnormal in three (42.9%) and four patients (57.1%), respectively. These electrophysiological parameters were correlated with the ratio of serum cholestanol to cholesterol concentration. The results of SSEPs suggest that the polyneuropathy in CTX is caused by distal axonopathy affecting longer axons before shorter axons (central-peripheral distal axonopathy).     

Electrophysiological studies in spinocerebellar ataxia type 6: a statistical approach

In spinocerebellar ataxia type 6 (SCA6), the cerebellum is predominantly affected, but several electrophysiological studies have revealed subclinical disorders other than cerebellar lesions. We conducted statistical analyses by comparing SCA6 patients and age-matched normal controls to asses whether electrophysiological abnormalities are directly associated with SCA6 because late onset of SCA6 may involve senile changes. We performed brain stem auditory evoked potentials (BAEP), visual evoked potentials, somatosensory evoked potentials and nerve conduction studies in 10 SCA6 patients. The BAEP latencies of wave I was prolonged and compound muscle action potentials of peroneal nerve and sensory nerve action potentials of sural nerve reduced in SCA6 patients. Our results suggest an existence of peripheral impairment in the auditory pathway and axonal neuropathy in SCA6.     

Ataxia and areflexia in SOAA

Fifteen patients with the classical syndrome of ophthalmoplegia, ataxia, and tendon areflexia (SOAA) were studied in an attempt to clarify the mechanisms of ataxia and myotatic hyporeflexia. All showed features of cerebellar rather than sensory ataxia. Peripheral nerve conduction studies, including F-waves, were normal in a majority of the patients, as was needle EMG. Low-amplitude compound sensory nerve potentials were seen in four patients only, and mild slowing of sensory conduction velocity in two. Three had abnormal blink reflex studies, suggestive of a central lesion in two, and another two showed a transient delay of N5 peak of brainstem auditory evoked potentials. Somatosensory evoked potentials were normal. Despite clinically depressed or absent tendon jerks, T-waves were elicited at normal latencies. These findings do not support the prevailing view that the neurological abnormalities in SOAA are due to involvement of sensory fibres in the peripheral nerves and dorsal roots. We suggest that lesions scattered in the brainstem tegmentum and in the cerebellar peduncles are responsible for the ataxia and the depressed tendon jerks.     

糖尿病周围神经病电生理特点及与血糖水平的关系

目的研究糖尿病周围神经病的神经电生理特点以及与血糖水平的关系。方法分析2013年3月~2014年3月于本院神经内科住院的108例糖尿病周围神经病患者,测定其正中、尺、胫、腓总神经的运动传导速度(MCV)和复合肌肉动作电位波幅(CMAP),以及正中、尺、腓肠神经、腓浅神经的感觉传导速度(SCV)和感觉神经动作电位波幅(SNAP),比较上、下肢和运动、感觉神经异常情况,分析糖化血红蛋白(HbA1C)、餐后2 h血糖对神经传导速度(NCV)的影响。结果糖尿病患者下肢运动神经病变重于上肢,且差异明显(P<0.05)。感觉神经损害重于运动神经,且差异明显(P     

Electrophysiological studies in five cases of abetalipoproteinemia

Auditory brainstem responses (ABRs), visual and somatosensory evoked responses (VEPs and SEPs) and nerve conduction studies were conducted in 5 patients with abetalipoproteinemia. The ABRs were normal in all cases. The VEPs were of normal amplitude but of increased latencies in two patients. The four eldest patients had delayed cortical SEPs but normal peripheral sensory nerve conduction studies. The peripheral motor conduction velocities were normal in all cases. The peripheral sensory studies showed normal velocity when a response was seen; however, the amplitude of the response was often reduced or it was absent. The electrophysiological studies reported here support a model of axonal loss of large myelinated fibres with secondary demyelination in abetalipoproteinemia.     

Nitrous oxide: clinical and electrophysiologic investigation of neurologic complications

Prolonged exposure to nitrous oxide produces a recognized neurologic syndrome. We report clinical and electrophysiologic studies of nervous system involvement in a 25-year-old student who abused nitrous oxide. He developed signs of a sensorimotor polyneuropathy and of myelopathy. Routine blood studies, CSF examination, and myelogram were normal. Clinical electrophysiologic studies were performed serially. Nerve conduction studies demonstrated reduced amplitude and slowed sensory potentials, and mildly prolonged late responses. Sensory evoked potentials revealed prolonged latency of scalp-evoked potentials from tibial nerve stimulation with normal median nerve values. The foveal visual evoked potential was delayed in the right eye, with normal visual acuity, funduscopic examination, and spatial contrast sensitivity. Repeat electrophysiologic studies demonstrated improvement. Nitrous oxide produces multifocal reversible dysfunction within the nervous system similar to that described in patients with vitamin B12 deficiency.     

Axonal neuropathy in chronic peripheral arterial occlusive disease

Chronic peripheral arterial occlusive disease of the lower limbs may cause tissue damage. Type and extent of peripheral nerve involvement is controversial. We examined 25 patients with peripheral arterial occlusive disease in various grades of severity and 37 age-matched healthy controls using conventional angiography and motor and sensory nerve conduction tests. Subjects with confounding factors for peripheral neuropathies were excluded. We found prolongation of distal motor latencies, decrease of motor and sensory nerve conduction velocities, and reduction in amplitude of the compound muscle action potential. Amplitudes of the compound muscle action potentials were lower in patients with pain at rest than in patients with intermittent claudication and decreased with increasing neurological disability score. Sural nerve conduction velocity, peroneal nerve F-wave chronodispersion, and tibial nerve F-wave persistence were the most frequent abnormal findings. Therefore we concluded that chronic peripheral arterial occlusive disease causes axonal degeneration, resulting in axonal polyneuropathy.