Abolished laser-evoked potentials and normal blink reflex in midlateral medullary infarction

We investigated two patients presenting with the rare finding of almost isolated hemianalgesia with a sensory level on the contralateral side sparing the face. Clinical findings, electrophysiological studies (absent laser-evoked pain-related somatosensory potentials, normal electrically evoked somatosensory potentials, magnetically evoked potentials, and blink reflexes), and magnetic resonance imaging showed the ventrolateral medullar tegmentum containing the spinothalamic tract to be affected by lacunar infarction. The blink reflex R2 component was unimpaired in both patients. Received: 7 May 1998 Received in revised form: 21 July 1998 Accepted: 26 August 1998     

Electrophysiological findings in neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a common, autosomal dominant neurocutaneous disorder in which any organ system, including the skin, skeleton and nervous system can be affected. In this study, we compared the electrophysiological and magnetic resonance imaging (MRI) findings in patients with NF1. Thirty-nine adolescent and adult patients (23 women and 16 men) diagnosed with NF1 with a mean age of 25.8±10 years (10-56) were included in this study. We collected data in the form of the results of neurological examinations, multimodal evoked potentials (EPs; brainstem auditory evoked potentials, BAEPs; somatosensory evoked potentials, SEPs; and visual evoked potentials, VEPs), cerebral/orbital/spinal MRIs, and electroneuromyography (ENMG). Twenty (51.3%) patients showed abnormal VEPs, 14 (35.9%) showed abnormal SEPs, and six (15.4%) showed abnormal BAEPs. All evoked potentials were abnormal in four (10.3%) cases. These electrophysiological findings occurred primarily in the absence of any clinical sign related to the affected system. MRI revealed pathologic findings in 26 of 39 patients, and these were not always correlated with visual, auditory, or somatosensory pathway abnormalities. ENMG showed polyneuropathy in two of 33 patients who underwent ENMG. Our study showed that MRI and electrophysiological abnormalities may be found in most patients with NF1, even in the absence of associated clinical symptoms or signs. Electrophysiological testing is helpful for monitoring the subclinical involvement of the central and peripheral nervous systems in patients with NF1.     

Utility of multimodal evoked potentials study in neurofibromatosis type 1 of childhood

A group of 21 children affected by neurofibromatosis type 1 has been investigated with the aim of studying multimodal (visual, brainstem auditory, and somatosensory) evoked potentials and their correlations with neurologic, electroencephalographic, and cranial magnetic resonance imaging. In the present series, cranial magnetic resonance imaging and evoked potentials were the most frequently abnormal instrumental tests. In approximately two thirds of the cases at least one of the evoked potentials (particularly visual and auditory evoked potentials) was compromised, always without clinical signs of related sensory (visual, auditory, and somatosensory) pathway pathology and sometimes in the absence of magnetic resonance imaging signs of central nervous system involvement. This study indicates that in patients with neurofibromatosis type 1, multimodal evoked potentials are useful and should be part of the diagnostic protocol of encephalic lesions together with magnetic resonance imaging. The use of both methods could aid in early detection of central nervous system dysfunction in both the initial evaluation of disease and its follow-up.     

Hereditary neuronal intranuclear inclusion disease with autonomic failure and cerebellar degeneration

BACKGROUND: Neuronal intranuclear inclusion disease (NIID), a multiple-system degeneration, occurs usually as a sporadic disorder with onset in childhood. The disease has been found in monozygotic twins and in siblings. In 2 previously described families, the disorder has affected 2 generations. OBJECTIVE: To investigate the clinical, anatomical, and electrophysiological characteristics of NIID that affect the central nervous system and the central and peripheral components of the autonomic nervous system in 2 successive generations of a family. DESIGN: Case report. SETTING: Tertiary care hospital. PATIENTS: A 53-year old woman and her sons, aged 28 and 25 years. Symptoms began in childhood in 2 of the 3 cases, and consisted of urinary and fecal incontinence, erectile dysfunction in the men, and recurrent orthostatic hypotension. METHODS: We used results of clinical neurological evaluations; cranial magnetic resonance imaging; skeletal muscle and sphincter electromyography (EMG); peripheral nerve conduction and bulbocavernosus reflex studies; autonomic function tests; brainstem, visual, somatosensory, and motor evoked potentials; auditory and vestibular testing; metabolic and molecular genetic testing; and muscle and rectal biopsy with immunohistochemistry. RESULTS: We found variable degrees of ocular dysmetria in 2 cases, ataxic dysarthria and limb ataxia in 1, and hyperreflexia in 2. Magnetic resonance imaging revealed cerebellar atrophy in all 3 cases and diffuse cerebral cortical atrophy in 1. Results of peripheral nerve conduction studies were normal. Sphincter EMG findings were abnormal in 2 of the 3 cases, and results of autonomic function tests were abnormal in the same 2. The EMG in 1 case revealed a chronic neurogenic pattern in the distal limb muscles. Metabolic and molecular genetic testing revealed no abnormal findings. Results of the muscle biopsy were negative, but results of the rectal biopsy revealed eosinophilic ubiquitinated intranuclear inclusions in neurons. CONCLUSION: Transmission of NIID in 2 generations presenting with autonomic failure and cerebellar ataxia was hereditary.     

Congenital hemiparesis: different functional reorganization of somatosensory and motor pathways.

OBJECTIVES: To investigate the reorganization of somatosensory and motor cortex in congenital brain injury. METHODS: We recorded motor evoked potentials (MEPs) following transcranial magnetic stimulation (TMS) and somatosensory evoked potentials (SEPs) in a 41 year old man with severe congenital right hemiparesis but only mild proprioceptive impairment. Brain magnetic resonance imaging showed a large porencephalic cavitation in the left hemisphere mainly involving the frontal and parietal lobes. RESULTS: TMS showed fast-conducting projections from the undamaged primary motor cortex to both hands, whereas MEPs were not elicited from the damaged hemisphere. Left median nerve stimulation evoked normal short-latency SEPs in the contralateral undamaged somatosensory cortex. Right median nerve stimulation did not evoke any SEP in the contralateral damaged hemisphere, but a middle-latency SEP (positive-negative-positive, 39-44-48 ms) in the ipsilateral undamaged hemisphere, with a fronto-central scalp distribution. CONCLUSIONS: Our data show that somatosensory function of the affected arm is preserved, most likely through slow-conducting non-lemniscal connections between the affected arm and ipsilateral non-primary somatosensory cortex. In contrast, motor function was poor despite fast-conducting ipsilateral cortico-motoneuronal output from the primary motor cortex of the undamaged hemisphere to the affected arm. This suggests that different forms of reorganization operate in congenital brain injury and that fast-conducting connections between primary cortex areas and ipsilateral spinal cord are not sufficient for preservation or recovery of function.     

Ataxia telangiectasia in Chinese children. A clinical and electrophysiological study

The clinical manifestations, immunological, chromosomal, and multimodal electrophysiological studies of five Chinese patients with ataxia telangiectasia are described. One died of hepatocellular carcinoma not associated with Hepatitis B-antigenaemia. Another died of respiratory failure. Two siblings are free of sinopulmonary infections although they are wheelchair bound. Computed tomography of the brain showed cerebellar atrophy in four cases. Nerve conduction studies showed evidence of axonal neuropathy in all cases with the earliest detection at six years. Electromyography showed mild denervation changes in two cases. Two patients had abnormal somatosensory evoked potentials and one had abnormal visual and brain stem auditory evoked potentials. The level of alpha foetal protein was elevated whereas the serum carcino-embryonic antigen was normal in all patients.     

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.     

First report of two Taiwanese siblings with sialidosis type I: a 10-year follow-up study

We report the clinical features, electrophysiological findings and genetic characteristics of the first two Taiwanese siblings ever reported with sialidosis type I. We also provide a 10-year follow-up result. Enzymological analysis revealed a primary sialidase deficit. The back-averaged electroencephalography demonstrated myoclonic jerk-related cortical activities and the somatosensory evoked potential studies revealed giant cortical components. During the 10-year follow-up, the brain magnetic resonance images of the younger brother remained normal, whereas they showed mild cerebellar atrophy in the older sister. Macular cherry red spots were absent in both siblings. However, visual evoked potential revealed progressively prolonged latencies of P100 bilaterally, which was consistent with progressive deterioration of the siblings' visions. DNA analysis showed that the siblings had a homozygous missense point mutation c.544A-->G (Ser182Gly) in the exon 3 of the alpha-N-acetyl-neuraminidase (NEU1) gene. The mutation is predicted to cause a decreased sialidase activity but the mutant sialidase can still be targeted to the lysosomes, which may correlate with the mild clinical phenotypes and absent cherry red spots in the siblings.     

Evoked potentials in multiple system atrophy (MSA)

OBJECTIVES: To study the involvement of pyramidal tracts and sensory pathways in multiple system atrophy (MSA). MATERIALS AND METHODS: Evoked potential studies were performed in 45 MSA patients suffering from either MSA of cerebellar type (MSA-C) or MSA of parkinsonian type (MSA-P). RESULTS: Motor evoked potentials were normal in all MSA patients, whereas visual and somatosensory evoked potential abnormalities were found in about 40% of the MSA patients with no significant difference between the cerebellar (MSA-C) and parkinsonian (MSA-P) subgroup. Abnormal latencies of wave III in brainstem auditory evoked potentials were significantly more frequent in MSA-C. CONCLUSIONS: Abnormalities of somatosensory, visual and auditory evoked potentials are frequent findings in MSA, whereas abnormal motor evoked potentials are not a characteristic feature of the disease.     

嗅鞘细胞移植修复坐骨神经缺损

背景：研究表明,嗅鞘细胞有利于神经元存活并促进轴突再生。 目的：验证局部注射嗅鞘细胞治疗大鼠周围神经损伤的可行性。 方法：体外分离、培养SD大鼠嗅鞘细胞。40只SD大鼠切除坐骨神经1.0 cm,植入异体神经1.0 cm。随机分为2组,嗅鞘细胞组局部注射嗅鞘细胞,生理盐水组局部注射生理盐水。术后3个月检测体感诱发电位及运动诱发电位,光镜、电镜观察神经电生理恢复情况。 结果与结论：电镜观察嗅鞘细胞组大鼠在损伤区有较多神经纤维通过,明显多于生理盐水组(P < 0.01)。嗅鞘细胞组大鼠体感诱发电位及运动诱发电位的潜伏期及波幅明显优于生理盐水组(P < 0.01)。提示局部注射嗅鞘细胞能更好地恢复周围神经损伤后的功能。     

Neuromuscular consequences of prolonged hunger strike: an electrophysiological study.

OBJECTIVES: The purpose of this study was to determine the electrophysiological consequences of neuromuscular and central nervous system involvement in a group of patients presented with the neurological complications of a long-term hunger strike (HS). METHODS: Motor and sensory nerve conduction (NCV), F wave, somatosensory evoked potential (SEP) and motor evoked potential (MEP) studies were performed in 12 male and 3 female patients (mean age: 29.4) following HS. RESULTS: All patients whose weight loss was 11-31 (mean: 22.8) kg after 69-day HS, had neurological findings consistent with Wernicke's encephalopathy or Wernicke-Korsakoff syndrome. Abnormally prolonged latency and/or low amplitude sensory nerve action potentials were found in 7 patients. The amplitudes of compound muscle action potentials were significantly reduced in ulnar, median and tibial motor NCV studies as compared to the controls. F waves elicited by median nerve stimulation at wrist and muscle responses evoked by cervical and lumbar magnetic stimulation had significantly prolonged latencies. MEPs recorded from the lower extremities showed a slight prolongation in central conduction times. The cortical response latencies were prolonged in tibial SEPs. CONCLUSIONS: The most prominent finding in this patient group was the low amplitude of CMAPs elicited in motor NCV studies which was concluded to be resulted from the reversible muscular changes. The other electrophysiological findings suggested that peripheral nerves and long central nervous system pathways were also mildly involved.     

The electrophysiology of migraine

PURPOSE OF REVIEW: The pathophysiology of migraine is far from being understood. Electrophysiological methods are useful to investigate peripheral and central mechanisms underlying this disorder. The purpose of this review is to highlight the results of electrophysiological studies published during the last year and to examine their added value to our previous knowledge. RECENT FINDINGS: Studies by visual and auditory evoked potentials and event-related responses suggested that lack of habituation is the principal interictal abnormality of sensory processing in migraineurs. Recently confirmed for somatosensory and laser-evoked cortical potentials and for brainstem responses, it is also responsible for the increased intensity dependence of auditory evoked potentials. This abnormality is possibly caused by a reduced cortical preactivation level due to hypofunctioning subcortico-cortical aminergic pathways. Although studies of cortical excitability by transcranial magnetic stimulation have yielded conflicting results, results obtained using habituation of pattern-reversal visual evoked potentials to explore cortical excitability changes induced by repetitive transcranial magnetic stimulation strongly favour the hypothesis that migraine is characterized by a decreased level of preactivation excitability. With regard to pain mechanisms in migraine, electrophysiological studies of trigeminal pathways using nociceptive blink and corneal reflexes have confirmed that sensitization of central trigeminal nociceptors occurs during the attack, and may even persist interictally. SUMMARY: Scientific publications over the last year confirmed that electrophysiological methods are particularly suited to unravelling some of the pathophysiological mechanisms of migraine. To improve their future contribution, they need to be better standardized and to be correlated with behavioural, metabolic and genetic studies.     

Further evidence of involvement of central and peripheral sensory pathways in olivopontocerebellar atrophy

We report the electrophysiological findings of the central and peripheral somatosensory pathways in 20 patients with olivopontocerebellar atrophy. Changes in sensory action potentials of the median nerve were observed in 14 patients and consisted of reduced sensory potential amplitudes associated in 10 cases with an increase in distal latencies. Sixteen out of 20 patients also showed changes in somatosensory evoked potentials after stimulation of the median nerve, consisting of decreased amplitude of N13 (13 cases) and N20 (16 cases) components, associated with increased N9-N13 interpeak latency in 9 and N13-N20 in 14 patients. The origin of these alterations is discussed.     

大剂量甲钴铵治疗亚急性联合变性的临床、影像及电生理分析

目的：观察亚急性联合变性（SCD）患者的临床特点、影像学（MRI）、电生理表现及甲钻铵治疗前后的变化,评价其诊断价值和疗效。方法：选取15例SCD患者,检测血常规和血清维生素B12、叶酸浓度,进行周围神经传导速度、体感诱发电位、视觉诱发电位、听觉诱发电位及脊髓MRI检查,观察治疗前后血红蛋白、血清维生素B12浓度、MRI及电生理的变化,并进行神经功能评定。结果：经甲钴铵治疗后患者临床症状明显改善,脊髓MRI显示的颈胸髓内后索、侧素长条状等T1长T2异常信号,治疗后多数病灶缩小或消失,电生理改变亦明显好转。结论：MRI诊断SCD准确度高;电生理检查敏感度高,且可发现亚临床病灶。两者结合可有助于SCD的早期明确诊断。大剂量甲钻铵静脉滴注可迅速提高血清维生素B12浓度,吸收利用度好,能有效改善SCD患者的神经功能。     

Prognosis of conservatively treated patients with Pott's paraplegia: logistic regression analysis

OBJECTIVE: To evaluate the prognostic significance of various clinical, radiological, and neurophysiological findings in conservatively treated patients with Pott's paraplegia, using multiple regression analysis. METHODS: The study included 43 patients with Pott's paraplegia, managed conservatively. The diagnosis of Pott's spine was based on clinical, magnetic resonance imaging, and computed tomography or ultrasound guided aspiration biopsy. All patients were examined clinically, and motor evoked potentials (MEPs) to lower limbs and tibial somatosensory evoked potentials (SEP) were recorded. Outcome at six months was defined as good or poor. For evaluating predictors of outcome, 15 clinical, investigative, and evoked potential variables were analysed, using multiple logistic regression analysis. RESULTS: The age range of the patients was 16-70 years, and 22 were female. Mild spasticity with hyperreflexia only was seen in 13 patients. In the remaining, weakness was severe in eight, and moderate and mild in 11 patients each. Twenty patients had loss of joint position sensation. MEP and SEP were abnormal in 19 and 18 patients, respectively. On multiple regression analysis, the best model predicting six month outcome included power, paraplegia score, SEP, and MEP. CONCLUSION: Patients with Pott's paraplegia are likely to recover completely by six months if they have mild weakness, lower paraplegia score and normal SEPs and MEPs.     

Clinical and electrophysiological findings in various hereditary sensory neuropathies]

An electrophysiological study, comprehensive of peripheral sensory and motor conduction velocity (SCV, MCV), motor cortical stimulation (CS), median nerve somatosensory evoked potentials (SSEPs), brainstem evoked potentials (BAEPs) and sural nerve biopsy, was performed on 100 hereditary ataxia patients: 48 with Friedreich's ataxia (FA), 18 with Early Onset Cerebellar Ataxia (EOCA) and 34 with Autosomal Dominant Cerebellar Ataxia (ADCA). An early "peripheral" and "central" sensory impairment was observed in FA probably due to axonal loss and not related to disease severity or duration. On the contrary, BAEP and CS findings suggested a progressive involvement of the auditory and motor pathways. The presence of a non progressive sensory neuropathy allowed a distinction of EOCA patients in two groups: with and without peripheral neuropathy. The clinical and genetic heterogeneity was confirmed by the variability of evoked potential results. The ADCA patients showed the mildest degree of electrophysiologic abnormalities with an involvement of the peripheral pathways, both sensory and motor, more frequent than the central ones.     

Autosomal dominant cerebellar ataxia: Phenotypic differences in genetically defined subtypes?

Seventy-seven families with autosomal dominant cerebellar ataxia were analyzed for the CAG repeat expansions causing spinocerebellar ataxia (SCA) types 1, 2, 3, and 6. The SCA1 mutation accounted for 9%, SCA2 for 10%, SCA3 for 42%, and SCA6 for 22% of German ataxia families. Seven of 27 SCA6 patients had no family history of ataxia. Age at onset correlated inversely with repeat length in all subtypes. Yet the average effect of one CAG unit on onset age was different for each SCA subtype. We compared clinical, electrophysiological, and magnetic resonance imaging (MRI) findings to identify phenotypic characteristics of genetically defined SCA subtypes. Slow saccades, hyporeflexia, myoclonus, and action tremor proposed SCA2. SCA3 patients frequently developed diplopia, severe spasticity or pronounced peripheral neuropathy, and impaired temperature discrimination, apart from ataxia. SCA6 presented with a predominantly cerebellar syndrome and patients often had onset after 55 years of age. SCAI was characterized by markedly prolonged peripheral and central motor conduction times in motor evoked potentials. MRI scans showed pontine and cerebellar atrophy in SCA1 and SCA2. In SCA3, enlargement of the fourth ventricle was the main sequel of atrophy. SCA6 presented with pure cerebellar atrophy on MRI. However, overlap between the four SCA subtypes was broad.     

Sensory function in severe semilobar holoprosencephaly

We report a 4-year-old child with severe semi-lobar holoprosencephaly (HPE) not expected to survive after birth. Magnetic resonance imaging (MRI) revealed agenesis of the corpus callosum, absence of the third ventricle, fused thalami and basal ganglia. To investigate sensory function, visual, auditory and somatosensory evoked potential and imaging studies were carried out. The visual response evoked by human face stimuli evoked larger responses over the left side of the holosphere as compared to responses evoked by checkerboard pattern, while auditory evoked potentials were evident over the frontal regions to both pure tones and speech stimuli. No consistent scalp somatosensory evoked potentials were evident. This case demonstrates that electrophysiological measures are able to identify and quantify sensory processing not expected to be present based on the anatomical presentation of the cortex in a child with severe HPE.     

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。     

Spike topography and functional magnetic resonance imaging (fMRI) in benign rolandic epilepsy with spikes evoked by tapping stimulation

We performed a spike topography study and a functional magnetic resonance imaging (fMRI) in a female patient with benign rolandic epilepsy presenting single high-amplitude evoked spikes in response to somatosensory peripheral stimulation. The stimulus was delivered to the first finger of the right hand using a tendon hammer, which evoked a single spike followed by a slow wave, showing the maximal amplitude over the left central regions. fMRI showed that the contralateral sensory cortices (S1 and S2) and the motor cortex (M I) were activated during tapping stimulation. In 3 normal subjects, tapping stimulation produced no fMRl activation. This fMRI study documents a highly focal activation of sensorimotor areas related to subclinical evoked spikes in benign rolandic epilepsy.