Amnesic syndrome with a unilateral thalamic lesion: a case report

Summary A 40-year-old man suffered an attack of transient global amnesia. The anterograde amnesia receded after 2 days, but a deficit remained in the retrieval stage of memory, which impaired the recall of names and of the information necessary to give details of particular events. Computed tomography revealed ischaemic infarction in the left anterolateral thalamus.

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Zusammenfassung Bei einem 40jährigen Mann trat eine amnestische Episode auf. Die anterograde Amnesie dauerte nur 2 Tage, aber es blieb eine spezifische Gedächtnisstörung, die das Wiederfinden von verbalem Material, besonders von Namen, betraf, darüber hinaus aber auch den Zugang zu jenen spezifischen Informationen und Details behinderte, die der einzelnen Erinnerung ihren individuellen Charakter geben. Das CT zeigte einen ischämischen Infarkt im linken anterolateralen Thalamus.

     

Somatosensory evoked potentials in a case of neurosyphilis

Here we report median and common peroneal nerve SEPs in a patient with tabes dorsalis. SEPs were within normal limits following median nerve stimulation, but of prolonged latency for common peroneal nerve. This was in keeping with clinical findings of posterior column involvement confined to the lumbosacral tract and with pathological features of tabetic neurosyphilis.

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Sommario Gli autori riportano le caratteristiche dei potenziali evocati somatosensoriali del nervo mediano e peroneo comune in un paziente affetto da tabe dorsale. I potenziali evocati somatosensoriali sono risultati nei limiti della norma stimolando il nervo mediano ma di latenza aumentata per il nervo peroneo comune. Ciò risultava in accordo sia con le caratteristiche cliniche di segni di interessamento dei cordoni posteriori limitato al tratto lombosacrale che con le caratteristiche anatomopatologiche della neurosifilide.

     

Thalamic degeneration with negative prion protein immunostaining

A 34-year-old woman presented with an insidious 5-year history of cognitive decline and apathy, associated with hypersomnia, ataxia, and dysarthria. Magnetic resonance imaging of the brain showed cortical and subcortical atrophy. At autopsy we found abnormalities in the subcortical grey matter and brainstem, with a relatively preserved cerebral cortex. The thalami showed symmetrical neuronal loss and astrocytosis, particularly severe in the dorsal medial nucleus, followed by the lateral nuclei group. Prion protein immuno-staining was negative, and there was no spongiform change. No mutations were detected in the prion protein gene. Received: 23 April 1999/Received in revised form: 16 August 1999/Accepted: 8 October 1999     

Thalamic stroke: correlation of clinical symptoms, somatosensory evoked potentials, and CT findings

We studied 18 patients with a single ischemic thalamic lesion, who had somatosensory disturbances and/or central pain in the opposite hemibody, by correlating their clinical symptoms, somatosensory evoked potentials (SEPs), and computed tomography (CT) findings. Patients were divided into three groups: (1) those with somatosensory deficits, central pain, and abnormal SEPs, which comprised two thirds of the patients (classic thalamic pain syndrome), (2) those with somatosensory deficits, no central pain, and abnormal SEPs (analgetic thalamic syndrome), and (3) those with almost normal sense perception, central pain, and normal SEPs (pure algetic thalamic syndrome). CT evidence of a paramedian or anterolateral thalamic lesion might be an indicator for the development of central pain, because these types of infarctions occurred only in patients with the classic thalamic syndrome or the pure algetic thalamic syndrome. The differentiation of the thalamic syndrome into three subtypes is of prognostic value, because patients with a loss of cortical SEPs and a posterolateral ischemic thalamic lesion on the CT scan probably will not exhibit central pain.     

Thalamic aphasia associated with mitochondrial encephalopathy,lactic acidosis,and stroke-like episodes: A case report

BackgroundMitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) with aphasia is a rare disorder, with the associated aphasia reported as either Wernicke’s or Broca’s. Herein, we report a patient with MELAS complicated by thalamic aphasia.CaseA 15-year-old right-handed girl presented with headache, nausea, right homonymous hemianopsia, and aphasia. She could repeat words said by others, but had word-finding difficulty, paraphasia, and dysgraphia. Brain MRI revealed abnormal signals from the left occipital lobe to the temporal lobe and left thalamus, but Wernicke’s area and Broca’s area were not involved. Additionally, she had short stature, lactic acidosis, bilateral sensorineural hearing loss, and a maternal family history of diabetes and mild deafness. Based on clinical findings and the presence of a mitochondrial A3243G mutation, she was diagnosed with MELAS. With treatment, the brain MRI lesions disappeared and her symptoms improved. Her aphasia was classified as amnesic aphasia because she could repeat words, despite having word-finding difficulty, paraphasia, and dysgraphia. Based on MRI findings of a left thalamic lesion, we diagnosed her with thalamic aphasia.ConclusionThalamic aphasia may be caused by MELAS. Assessment of whether repetition is preserved is important for classifying aphasia.     

术中监护下神经导航显微手术切除功能区及深部病变

目的研究术中监护下神经导航手术切除功能区及深部病变的疗效.方法在神经导航引导的显微神经外科手术中,对32例脑功能区及深部病变病人进行正中神经N20、P25和胫后神经P40、N50体感诱发电位（SEP）监护,以及大鱼际肌和胫前肌运动诱发电位（MEP）监护,以指导手术操作.结果术后MR复查示均达到全切除.24例偏瘫病人中术后症状改善21例,17例癫癎病人中癫癎症状术后消失13例,12例失语病人中术后改善10例.术后未产生新的神经损害症状,无手术并发症及死亡.结论术中神经电生理监护对于提高脑功能区及深部区域病变的手术疗效和安全性有重要意义.     

20 and 40 somatosensory evoked potentials: Thalamic lesions and subcortical origin

Three patients with well-defined clinical and radiographic lesions have been studied with somatosensory evoked potentials (SSEPs). The data indicate that the primary scalp potentials from stimulation of both the arm and leg (N20 and P40) can be lost with thalamic lesions and would be consistent with these potentials being generated in either the thalamus or thalamocortical radiations.     

Somatosensory and visual evoked potentials in children with cerebral palsy: Correlations and discrepancies with MRI findings and clinical picture

Purpose: To determine if there is any association between the findings of visual evoked potentials (VEPs), somatosensory evoked potentials (SEPs), and magnetic resonance imaging (MRI) findings with the neurodevelopment and severity in children with cerebral palsy (CP). Methods: The present study included 15 children with spastic diplegic CP and five children with spastic hemiplegic CP and 42 healthy children as controls. The number of the controls was two-times greater than the study group to increase statistical power of this study. VEPs and SEPs were recorded in the CP children and compared with healthy controls. All MR scans were obtained using a 1.5 T MR scanner. Results: A significant difference was found in the latencies P100 (VEP) between the CP and controls. No correlations between increased P100 latencies and asphyxia, prematurity, the CP severity, MRI findings and mental retardation were noted. A significant difference in N13–N20 conductions (SEPs) between the subjects with CP and the control group was found. SEPs were positively correlated with mental retardation in CP children. The brain lesions in MRI showed a significant correlation with the CP severity scores and mental retardation. Conclusion: The differences in VEPs and SEPs were determined between CP children and healthy children. The MRI findings were positively correlated with the CP severity and mental retardation.     

Giant somatosensory evoked potentials in a patient with the anterior spinal artery syndrome

We studied a previously healthy 25-year-old woman with the anterior spinal artery syndrome, a rare thoracocervical myelopathy with multiple potential etiologies. Quantitative and clinical sensory examination showed dissociated loss of pin-prick and temperature discrimination below the level of the lesion, with normal light touch, vibratory, and position sense. Magnetic resonance imaging was consistent with cervical spinal cord infarction. Median SEPs showed normal Erb's potential with absent spinal N—₁₃ and normal scalp N—₂₀ latency. Tibial SEPs showed normal lumbosacral responses and normal scalp P—₃₀ latency. Both median and tibial nerve stimulation produced cortical responses of unusually large amplitude (median 38 m?V, tibial 17 m?V). We hypothesize that large SEP amplitudes in this patient resulted from loss of anterolateral inhibitory influences on the dorsal column–medial lemniscal system. © 1993 John Wiley & Soncs, Inc.     

大脑语言运动区手术中的神经电生理监测(附52例分析)

目的研究大脑语言运动区病变手术中神经电生理监测的方法。方法对52例病变位于语言运动区的病人采用术中唤醒全麻，联合监测皮质体感诱发电位、直接皮质电刺激、肌电图及脑电图，同时行显微手术切除病变。结果全切除42例，次全切除10例。术中记录到典型的皮质体感诱发电位38例，其中波形倒置23例，最大波幅者20例。皮质电刺激与体感诱发电位所判定的中央前回位置完全相符者33例．皮质体感诱发电位不典型者电刺激阳性5例。肌电图变化与肌肉运动相符者20例，肌电图出现反应波而未见肌肉运动者10例。脑电图示癫痫波20例，广泛性慢波40例。术后症状改善或消失47例。结论语言运动区病变采用术中唤醒全麻，联合监测皮质体感诱发电位、直接皮质电刺激、肌电图与脑电图等神经电生理指标，有助于在最大限度保留脑功能的前提下全切除病变．保证手术安全．明显减少术后功能障碍的发生。     

Abnormalities of somatosensory and motor evoked potentials in adrenomyeloneuropathy: Comparison with magnetic resonance imaging and clinical findings

We studied 6 patients with adrenomyeloneuropathy (AMN) showing mild signs of central nervous system involvement. All patients underwent brain and spinal magnetic resonance imaging (MRI) and somatosensory (SEP) and motor (MEP) evoked potential study. Whereas SEPs and MEPs were abnormal in all patients, only 1 patient showed brain MRI abnormalities; spinal MRI showed hypotrophy without focal abnormalities in 4 of 6 patients. Median nerve SEPs, which were recorded with noncephalic reference montage, revealed delayed or absent scalp P14 far-field potential in all patients and abnormal spinal N13 in 2. Moreover, tibial nerve SEPs revealed abnormalities of the subcortical P30 response in all 4 patients in whom scalp-to-ear recording was employed. These findings strongly suggest that in the early stages of disease neurological dysfunction is localized in the spinal cord, where it is difficult to assess using MRI. However, SEPs and MEPs, which show a typical pattern of abnormality in these patients, could be useful in disclosing signs of long tract involvement and in monitoring treatment. © 1997 John Wiley & Sons, Inc. Muscle Nerve 20: 1249–1257, 1997     

Visual evoked potential abnormalities in dementia with Lewy bodies

ObjectivesVisuo-perceptual deficits and visual hallucinations (VHs) are common disturbances in patients with dementia with Lewy bodies (DLB) and those with Parkinson’s disease (PD). In particular, delays in visual evoked potential (VEP), reversed by l-dopa administration, have previously been observed in PD patients. Impairment in metabolic functions of dopaminergic amacrine cells within the inner plexiform layer of the retina has been largely documented and has been posited as the underlying cause of visual and retinal alterations in PD. The aims of the present study were to investigate the presence of VEP abnormalities in DLB patients, as compared to a PD control group, and to assess the presence of significant correlations between neurophysiological measures and clinical symptoms (i.e., presence of visuospatial deficits and/or visual hallucinations).MethodsFifteen DLB patients and fifteen matched PD patients underwent pattern reversal before and after l-dopa administration, and a short neuropsychological assessment.ResultsIn DLB patients, we observed delay of the P100 latency to foveal stimuli in both eyes compared to normative values. Compared to PD, DLB patients showed higher values of the P100 latency for foveal stimulation from the right eye prior to l-dopa administration (p = 0.018). No correlations between VEP alterations, visuo-spatial deficit and visual hallucinations were found.DiscussionOur findings demonstrated a longer P100 delay in DLB than in PD patients, especially along the right visual pathway. In contrast to previous studies, which focused on a dopaminergic pre-geniculate impairment of visual pathways, our evidence suggests that other mechanisms, possibly relying on thalamic involvement, which is known to be dysfunctional in DLB, can interfere with VEP abnormalities.     

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.     

White matter lucencies in multi-infarct dementia: a somatosensory evoked potentials and CT study

White matter low attenuation (WMLA) on computed tomography (CT) and the central conduction time (CCT) measured by median nerve-somatosensory evoked potentials were examined in 12 multi-infarct dementia (MID) patients, 10 patients with multiple infarcts (MI) without dementia and 11 age-matched controls. Patients with deep vascular lesions without cortical infarcts on CT were included. In MID, prolongation of CCT and moderate to severe WMLA were observed. The CCT and WMLA in MI patients were intermediate. The CCT was longer when the WMLA was more extensive. The result suggests that white matter disease in MID is concerned to the occurrence of dementia by disturbing axonal conduction.     

An association of human T-cell lymphotropie virus type I infection with vascular dementia

Subjects ranging in age from 50 to 89 years old, either with or without dementia were studied by both ELISA for anti-human T-cell lymphotropie virus type I (HTLV-I) gag 100–130 antibody and by cranial CT in order to clarify the relationship between HTLV-I infection and dementia. The frequency of anti-HTLV-I antibody was found to be significantly higher in the patients with dementia (24/130,18.5%) than in those without dementia (11/139, 7.9%) ( P =0.0169). Among the various types of dementia, HTLV-I seropositivity was found to be significantly associated with vascular dementia (11/48,23%) ( P =0.0087), but not with Alzheimer type dementia. In addition, HTLV-I seropositivity was also associated with Babinski sign, and the severity of cerebral infarction, ventricular dilatation and periventricular lucency on CT. The presence of HTLV-I therefore appears to be one of the risk factors for vascular dementia in HTLV-I endemic areas.     

Cortical excitability changes associated with fixation-off sensitivity: a case report

"Fixation-off sensitivity" (FOS) is an ideal human model for studying the features of epileptic discharges. Physiologically, FOS is expected to correspond to enhanced excitability of widespread cortical structures. To test this hypothesis, we measured by transcranial magnetic stimulation (TMS), the excitability level of the primary motor area in a 22-year-old woman with eyelid myoclonias and absences, who presented with generalized FOS. We also explored her visual system by pattern-reversal and flash-visual evoked potentials (VEPs). Both outside and within FOS, the cortical silent period was dramatically short, indicating defective γ-aminobutyric acid (GABA)(B) inhibition as a persistent background factor. The same was true for the short-interval intracortical inhibition, a TMS marker of cortical GABA(A) inhibition. The FOS state corresponded then to a pathologic enhancement of intracortical facilitation, a TMS marker of Glu/Asp transmission. During FOS, the flash VEP exhibited a hugely enhanced afterdischarge, expressing a pathologic overactivity of secondary visual areas. Within the limits of a single-case study, we thus provide electrophysiologic evidence supporting a grossly imbalanced cortical excitability, in both the frontal and posterior areas, as an important correlate of the present FOS subtype.     

The effects of a supratentorial mass lesion on brain-stem auditory evoked potentials and short latency somatosensory evoked potentials

Nineteen patients with unilateral supratentorial mass lesion and without any evident clinical signs of transtentorial herniation were studied with Computed Tomography (CT), brain-stem evoked potentials (BAEPs) and central conduction time (CCT) of short latency somatosensory evoked potentials (SEPs). Sixteen had tumours, two had intracranial haematoma and one had chronic subdural haematoma. CT detected the initial signs of transtentorial herniation in every case. Preoperative I-V interpeak latency (IPL) was significantly (M+2SD) prolonged in 26% of cases on the lesion side and in 21% of cases on the opposite side. The mean I-V IPL was significantly prolonged both on the lesion side and the opposite side (P < 0.01, P < 0.02, respectively). Suppression of Wave V (M-2SD) was seen only in two cases, however, the mean amplitude of Wave V was significantly decreased both on the lesion side and on the opposite side (P < 0.001, P < 0.01, respectively). CCT of SEPs was significantly (M+2SD) prolonged in 33% of cases on the lesion side and in only 13% on the opposite side. The mean CCT was, however, significantly prolonged both on the lesion and on the opposite side (P < 0.001, P < 0.02, respectively). Postoperative I-V IPL was significantly prolonged in only 11% of cases while the mean I-V IPL was still significantly prolonged (P < 0.07) and the mean amplitude of Wave V was still suppressed (P < 0.001) on the lesion side. On the other hand, there was neither abnormality of I-V IPL nor suppression of Wave V on the opposite side. Postoperative CCT was significantly prolonged in 43% of cases and the mean CCT was also significantly (P < 0.01) prolonged on the lesion side. However, there was no prolongation of CCT on the opposite side. Preoperative findings of both BAEPs and SEPs show the abnormality due to the supratentorial lesion and postoperative findings of these potentials indicate both the effects of surgical decompression and the residual abnormalities due to the supratentorial mass lesion.     

Thalamic infarct presenting with thalamic astasia

Astasia, inability to stand unsupported despite good strength, resembles the marked balance impairment of patients with vestibulocerebellar disease. We describe a patient with unilateral thalamic infarct that presented with astasia. A 76-year-old hypertensive woman was admitted to our hospital because of marked unsteadiness. On neurological examination, she could not stand unsupported and the woman's body swayed back and forth markedly. The swaying was not compensated for by her taking a step forward or backward, and she frequently collapsed when support was withdrawn. Diffusion-weighted magnetic resonance image revealed a discrete infarct within the right posterolateral thalamus. Brain single photon emission computerized tomography revealed markedly decreased regional cerebral blood flow within in the right thalamus with concomitant left superior cerebellar region. We discuss the possible pathomechanisms of thalamic astasia.