Brain immunohistopathological study in a patient with anti-NMDAR encephalitis.

BACKGROUND AND PURPOSE: Anti-N-methyl-D-asparate (NMDA) receptor encephalitis is thought to be antibody-mediated. To perform an immunohistopathological study of the inflammatory reaction in a brain biopsy performed before immunomodulatory treatments in a patient with anti-NMDA receptor encephalitis. METHODS: An immunohistochemical study was performed using CD3, CD68, CD20, CD138 and CD1a antibodies. RESULTS: Prominent B-cell cuffing was present around brain vessels accompanied by some plasma cells, while macrophages and T cells were scattered throughout the brain parenchyma. CONCLUSION: These findings suggest that the B cells interact with the T cells and are involved in antibody secretion by the plasma cells.

[Small fiber sensory neuropathies: contribution of laser evoked potentials]. / Neuropathies sensitives des petites fibres : intérêt des potentiels évoqués laser.

Standard neurophysiological techniques evaluate exclusively large myelinated fibers, but are not useful to explore sensory small fibers. Quantitative sensory tests have been developed to explore the thermal nociceptive function but this exploration is only subjective. Laser evoked potentials (LEPs) represent a noninvasive and objective test to explore thermal and nociceptive pathways. The clinical interest of LEPs have been assessed recently in the diagnosis of small fibers sensory neuropathies. In routine, the determination of detection and nociceptive thresholds, the analysis of N2P2 latencies and amplitudes enable demonstration of a dysfunction of A delta nerve fibers, to quantify these lesions and to determine whether the neuropathies are length-dependent or not. The LEP amplitude is negatively correlated to deafferentation. The interest of LEPs remained to be studied compared to skin biopsy.

[Differential diagnosis of status epilepticus]. / Diagnostics différentiels des états de mal épileptiques.

The diagnosis of status epilepticus can be retained, wrongly, in several circumstances. Nonepileptic pseudoseizures from a psychiatric origin and some movement disorders can mimic convulsive status epilepticus. Encephalopathy of various causes (post-anoxic, metabolic, toxic, Creutzfeldt-Jakob disease) can be wrongly taken for non-convulsive status epilepticus, mainly due to inadequate interpretation of the electroencephalogram (EEG). In these encephalopathies, the existence of (non-epileptic) myoclonus and the abolition of the EEG abnormalities with the use of a benzodiazepine (without correction of the clinical symptoms) are additional confounding factors, leading to false diagnosis. Nevertheless, in general, the diagnosis of status epilepticus can be confirmed or rejected base on a combined analysis of the clinical data and the EEG.

An odd manifestation of the Capgras syndrome: loss of familiarity even with the sexual partner.

We report the case of a patient who presented visual hallucinations and identification disorders associated with a Capgras syndrome. During the Capgras periods, there was not only a misidentification of his wife's face, but also a more global perceptive and emotional sexual identification disorder. Thus, he had sexual intercourse with his wife's "double" without having the slightest recollection feeling of familiarity towards his "wife" and even changed his sexual habits. To the best of our knowledge, he is the only neurological patient who made his wife a mistress. Starting from this global familiarity loss, we discuss the mechanism of Capgras delusion with reference to the role of the implicit system of face recognition. Such behavior of familiarity loss not only with face but also with all intimacy aspects argues for a specific disconnection between the ventral visual pathway of face identification and the limbic system involved in emotional and episodic memory contents.

Central representation of the RIII flexion reflex associated with overt motor reaction: an fMRI study.

Recent neuroimaging studies precised the functions of the brain regions included in the so-called "pain-matrix". They isolated brain structures mediating attentional, emotional, anticipatory, cognitive, and discriminative aspects of pain perception. Surprisingly, little attention was devoted to isolate the cerebral network associated with the motor response to pain. In this study, we used fMRI to measure BOLD signal changes in nine volunteers while they received low- (L-) and high- (H-) intensity painful electrical shocks on the (left) lower limb. High-intensity stimulation was associated with a significantly stronger pain sensation and with a pronounced motor (withdrawal) reflex. BOLD responses common to L- and H-stimulation intensities were found in the right prefrontal and right posterior parietal cortices. These did not correlate with subjective pain ratings and probably mediate attentional processes unrelated to pain intensity and withdrawal. In contrast, signal changes in insula, left SII cortices and right amygdala did correlate with pain ratings and are therefore likely to encode for pain intensity. High-intensity shocks selectively recruited a motor network, including vermis, MI, SI, and paracentral cortices bilaterally, right premotor, right SII and posterior cingulate cortices. These responses, assessed for the first time in a functional imaging study, emphazised on the presence of a motor component in what has been described as the pain-matrix. They should be considered as a motor component of pain-related processes activated in case of intense pain.

EEG in adults in the laboratory or at the patient's bedside.

Electroencephalogram (EEG) recording in the laboratory lasts at least 20 minutes and uses 19 active electrodes. It includes rest periods, stimulation procedures, a 3-mn hyperventilation period and intermittent photic stimulation (IPS). Recorded at the bedside, the EEG uses at least eight electrodes; the stimulation procedures, duration of the EEG and need to repeat the examination depend on the indication. Simultaneous video recording is recommended. The EEG report describes the basic rhythm, its reactivity and pathological activities, whether epileptic or not, and their organization. The synthetic conclusion interprets the results while taking into account the clinical context and contributes, if possible, diagnostic and/or therapeutic help in patient management. EEG performed as soon as possible after a seizure is essential for the diagnosis and initial management of epilepsy. It is helpful to characterize the epileptic syndrome in order to initiate optimal treatment. EEG is also useful in managing the withdrawal of antiepileptic drugs. EEG is also extremely useful in case of impaired consciousness, confusional state or even acute or subacute cognitive disorders. It is the only available tool able to validate the diagnosis of non-convulsive status epilepticus presenting with confusional state. EEG helps in the diagnosis of toxic or metabolic encephalopathy and can assess its severity, especially in hepatic encephalopathy. Except in rare exceptions, EEG is not routinely indicated for the evaluation of typical vasovagal syncope, headaches, dizziness, typical transient global amnesia and transient ischemic attack. EEG is irreplaceable in the diagnosis and management of certain severe and frequent pathologies involving the cerebral cortex.

Somatosensory evoked potentials in the assessment of peripheral neuropathies: Commented results of a survey among French-speaking practitioners and recommendations for practice.

BACKGROUND: Somatosensory evoked potentials (SSEPs) are increasingly performed for the assessment of peripheral neuropathies, but no practical guidelines have yet been established in this specific application. STUDY AIM: To determine the relevant indication criteria and optimal technical parameters for SSEP recording in peripheral neuropathy investigation. METHODS: A survey was conducted among the French-speaking practitioners with experience of SSEP recording in the context of peripheral neuropathies. The results of the survey were analyzed and discussed to provide recommendations for practice. RESULTS: SSEPs appear to be a second-line test when electroneuromyographic investigation is not sufficiently conclusive, providing complementary and valuable information on central and proximal peripheral conduction in the somatosensory pathways. CONCLUSIONS: Guidelines for a standardized recording protocol, including the various parameters to be measured, are proposed. CLINICAL RELEVANCE: We hope that these proposals will help to recognize the value of this technique in peripheral neuropathy assessment in clinical practice.

Unusual amyloid polyneuropathy with predominant lumbosacral nerve roots and plexus involvement.

We report a 25-year-old patient with a progressive asymmetric peripheral neuropathy of the distal lower limbs. Imaging studies showed enlargement of lumbosacral roots, plexus, and proximal sciatic nerve. Sacral plexus biopsy revealed amyloidosis associated with endoneurial edema. Immunohistochemistry with anti-prealbumin, serum amyloid A, and immunoglobulin light chain antisera failed to label the amyloid.

Electrical stimulation of precentral cortical area in the treatment of central pain: electrophysiological and PET study.

The clinical, electrophysiological and haemodynamic effects of precentral gyrus stimulation (PGS) as a treatment of refractory post-stroke pain were studied in 2 patients. The first patient had a right hemibody pain secondary to a left parietal infarct sparing the thalamus, while the second patient had left lower limb pain developed after a right mesencephalic infarct. In both cases, spontaneous pain was associated with hyperpathia, allodynia and hypoaesthesia in the painful territory involving both lemniscal and extra-lemniscal sensory modalities in patient 1, extra-lemniscal sensory modality only in patient 2. Both patients were treated with electrical PGS by means of a 4-pole electrode, the central sulcus being per-operatively located using the phase-reversal of the N20 wave of somatosensory evoked potentials. No sensory side effect, abnormal movement or epileptic seizure were observed during PGS. The analgesic effects were somatotopically distributed according to the localization of electrode on motor cortex. A satisfactory long-lasting pain control (60-70% on visual analog scale) as well as attenuation of nociceptive reflexes were obtained during PGS in the first patient. Pain relief was less marked and only transient (2 months) in patient 2, in spite of a similar operative procedure. In this patient, in whom PGS eventually evoked painful dysethesiae, no attenuation of nociceptive RIII reflex could be evidenced during PGS. Cerebral blood flow (CBF) was studied using emission tomography (PET) with O-labeled water. The sites of CBF increase during PGS were the same in both patients, namely the thalamus ipsilateral to PGS, cingulate gyrus, orbito-frontal cortex and brainstem. CBF increase in brainstem structures was greater and lasted longer in patient 1 while patient 2 showed a greater CBF increase in orbito-frontal and cingular regions. Our results suggest that PGS-induced analgesia is somatotopically mediated and does not require the integrity of somatosensory cortex and lemniscal system. PGS analgesic efficacy may be mainly related to increased synaptic activity in the thalamus and brainstem while changes in cingulate gyrus and orbito-frontal cortex may be rather related to attentional and/or emotional processes. The inhibitory control on pain would involve thalamic and/or brainstem relays on descending pathways down to the spinal cord segments, leading to a depression of nociceptive reflexes. Painful dysesthesiae during stimulation have to be distinguished from other innocuous sensory side effects, since they may compromise PGS efficacy.

Parietal and cingulate processes in central pain. A combined positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) study of an unusual case.

Parietal, insular and anterior cingulate cortices are involved in the processing of noxious inputs and genesis of pain sensation. Parietal lesions may generate central pain by mechanisms generally assumed to involve the 'medial' pain system (i.e. medial thalamic nuclei and anterior cingulate cortex (ACC)). We report here PET and fMRI data in a patient who developed central pain and allodynia in her left side after a bifocal infarct involving both the right parietal cortex (SI and SII) and the right ACC (Brodmann areas 24 and 32), thus questioning the schematic representation of cortical pain processing. No rCBF increase was found in any part of the residual cingulate cortices, neither in the basal state (which included spontaneous pain and extended hypoperfusion around the infarct), nor during left allodynic pain. Thus, as previously observed in patients with lateral medullary infarct, neither spontaneous pain nor allodynia reproduce the cingulate activation observed after noxious pain in normal subjects. Conversely, both PET and fMRI data argue in favour of plastic changes in the 'lateral discriminative' pain system. Particularly, allodynia was associated with increased activity anteriorly to the infarct in the right insula/SII cortex. This response is likely to be responsible for the strange and very unpleasant allodynic sensation elicited on the left side by a non-noxious stimulation.

Electrical stimulation of motor cortex for pain control: a combined PET-scan and electrophysiological study.

Although electrical stimulation of the precentral gyrus (MCS) is emerging as a promising technique for pain control, its mechanisms of action remain obscure, and its application largely empirical. Using positron emission tomography (PET) we studied regional changes in cerebral flood flow (rCBF) in 10 patients undergoing motor cortex stimulation for pain control, seven of whom also underwent somatosensory evoked potentials and nociceptive spinal reflex recordings. The most significant MCS-related increase in rCBF concerned the ventral-lateral thalamus, probably reflecting cortico-thalamic connections from motor areas. CBF increases were also observed in medial thalamus, anterior cingulate/orbitofrontal cortex, anterior insula and upper brainstem; conversely, no significant CBF changes appeared in motor areas beneath the stimulating electrode. Somatosensory evoked potentials from SI remained stable during MCS, and no rCBF changes were observed in somatosensory cortex during the procedure. Our results suggest that descending axons, rather than apical dendrites, are primarily activated by MCS, and highlight the thalamus as the key structure mediating functional MCS effects. A model of MCS action is proposed, whereby activation of thalamic nuclei directly connected with motor and premotor cortices would entail a cascade of synaptic events in pain-related structures receiving afferents from these nuclei, including the medial thalamus, anterior cingulate and upper brainstem. MCS could influence the affective-emotional component of chronic pain by way of cingulate/orbitofrontal activation, and lead to descending inhibition of pain impulses by activation of the brainstem, also suggested by attenuation of spinal flexion reflexes. In contrast, the hypothesis of somatosensory cortex activation by MCS could not be confirmed by our results.

Thrombotic thrombocytopenic purpura: MR findings.

Neurologic manifestations occur in over 90% of patients with thrombotic thrombocytopenic purpura. Neuropathologically, thrombi produce occlusion of terminal arterioles and capillaries resulting in diffuse small infarcts. In the great majority of surviving patients, brain CT does not disclose any abnormalities. The authors report a case of thrombotic thrombocytopenic purpura in which brain MR examination showed multiple punctate lesions in the white matter.

Pathology of roots, spinal cord and brainstem in syringomyelia-like syndrome of Tangier disease.

We report here a post-mortem examination of a 46-year-old patient who died after a 23-year-long syringomyelia-like syndrome of Tangier disease. The L5 dorsal root and the superficial peroneal nerve showed fiber loss and lipid vacuole accumulation in Schwann cell cytoplasm. The L5 ventral root had moderate fiber loss without lipid vacuoles. In the cervical roots, fiber loss was intense and there were no foamy Schwann cells. Motor neuron loss was severe in the cervical spinal cord and the facial nerve nucleus and slight at the lumbar level. Under electron microscopy, some neurons of the lower spinal cord showed atypical inclusions. These data suggest that an unknown metabolic defect is responsible for a primary neuronopathy. Lipid accumulation in Schwann cells, resulting from fiber degeneration is probably transient, accounting for the absence of foamy cells in regions with longstanding involvement.

[Anomalies in early somatosensory evoked potentials in brain stem lesions (study of 64 cases)]. / Les anomalies des potentiels évoqués somesthésiques précoces dans les lésions du tronc cérébral (étude de 64 observations).

Short latency somatosensory evoked potentials (SEPs) have been recorded in 64 patients with brainstem lesions documented by neuroimaging techniques. Patients were classified in four groups according to the lesion topography: cervico-medullary junction and medulla (16 cases), pons (19 cases), mesencephalon (8 cases), extensive (21 cases). SEPs were abnormal in 57.8% of cases either bilaterally (17.2%), or unilaterally (40.6%). The different components were affected as follows, P14: 34.4%; N20: 56.9%; P22 and N30: 54.7%, peripheral and spinal responses were always spared: N18 and P14 abnormalities were highly correlated. In cervico-medullary lesions P14 and N20 were constantly abnormal, P14 was normal in strictly mesencephalic lesions but could be abnormal in cases of subthalamic lesions with mesencephalic extension; in pontic lesions, P14 could be normal or not, and N20 was always very reduced. These results confirm that P14 has a supra-spinal origin and may have two generators. SEPs detected a subclinical dysfunction of the lemniscal pathways in 18% of patients with normal somatosensory performances and, as BAEPs (abnormal in 54% of the 54 recordings performed in this series) deserve to be recorded for the routine investigation of brainstem function.

Cognitive effects of precentral cortical stimulation for pain control: an ERP study.

Electrical stimulation of the motor cortex (MCS) is a promising and increasingly used neurosurgical technique for the control of refractory neuropathic pain. Although its mechanisms of action remain unknown, recent functional imaging data suggest involvement of the thalamus, brainstem and anterior cingulate/orbitofrontal cortex. Since some of these areas are also implicated in higher cognitive functions, notably attentional processes, we analysed cognitive ERPs and behavioural performance during an "oddball" auditory detection task in patients submitted to this procedure. Eleven consecutive patients undergoing MCS because of neuropathic refractory pain, ranging in age from 25 to 71 years, were included in the study. ERPs were obtained in all cases both during the application ("MCS-on") and within the 10 min that followed discontinuation of the procedure ("MCS-off"). In five patients, ERPs could also be obtained just before the start of MCS. When the patients' sample was taken as a whole, there were no consistent effects of MCS on the ERPs. There was, however, a significant interaction of MCS action with the patients' age, reflecting a significant delay during MCS of the cognitive responses N2 and P3 (N200 and P300) in the group of patients older than 50 years exclusively. This effect was rapidly reversible after MCS discontinuation. No MCS-related changes were observed in the N1 component. At the individual level, the effect of MCS on the endogenous ERPs was highly variable, ranging from a total stability of ERPs (mostly in younger subjects) to latency differences of tens of milliseconds in the older group. These results, together with recent experiments showing P300 alteration during repetitive transcranial stimulation, suggest that motor cortex stimulation may interfere with relatively simple cognitive processes such as those underlying target detection, and that the risk of abnormal cognitive effects related to cortical stimulation may increase with age. Although the procedure appears on the whole remarkably safe, complementary neuropsychological studies in this category of patients are advised, as well as caution to possible adverse cognitive effects when using MCS in the elderly, notably in the presence of pre-existent cerebral lesions.

[Post-traumatic syringomyelobulbia and inferior vertical nystagmus]. / Syringomyélobulbie post-traumatique et nystagmus vertical inférieur.

A case of post-traumatic cervico-thoracic syringomyelia was complicated, 3 years after the injury, by a bulbar extension manifested by a downbeat vertical nystagmus which became a source of disabling oscillopsia. The syringobulbia was visualized at MRI. The usefulness of syringostomy in such a case is discussed.

[Dissecting aneurysm of the intracranial vertebral artery. An anatomo-clinical case]. / Anévrysme disséquant de l'artère vertébrale intracrânienne. Un cas anatomo-clinique.

A 64 year old patient with a cardiac prosthesis and receiving antivitamin K therapy presented with a right bulbar syndrome. Based on absence of meningeal signs and hemorrhage on CT scan heparin therapy was instituted. Fatal coma developed two and a half days later. Autopsy findings included a right lateral bulbar infarct and meningeal hemorrhage, predominant around a fusiform dilatation of the end of the right vertebral artery. Serial sections showed a large dissecting aneurysm between media and adventitia communicating with an intimal tear. Among intracranial dissecting aneurysms those of vertebrobasilar localization have the peculiarity of being subadventitial in some cases, with a subsequent enhanced risk of hemorrhagic complications. The use of anticoagulants appears contraindicated in these cases, even if their clinical expression is suggestive of an infarct. Their etiology is often unknown.

[Unilateral scapulohumeral amyotrophy. Contribution of imaging]. / Amyotrophie scapulo-humérale unilatérale. Apport de l'imagerie.

A case of right scapulohumeral muscular atrophy stable after a 6 month progressive course is reported. Cervical metrizamide CT and MRI showed a flattened right cervical spinal cord regarded as a segmental atrophy. The case could belong to the Kaeser type of sporadic chronic spinal amyotrophy, or perhaps corresponds to a benign focal amyotrophy.

[Contribution of magnetic resonance imaging in 100 cases of refractory partial epilepsy with normal CT scans]. / Apport de l'imagerie par résonance magnétique dans 100 cas d'épilepsie partielle rebelle à scanner X normal.

One hundred epileptic patients were included in this study according to the following criteria: intractable partial epilepsy, normal CT scan and focal EEG abnormalities. Eighty-nine patients were suffering from complex partial seizures of temporal or frontal origin, 55 and 34 cases respectively. Eleven patients presented with only simple partial seizures. MRI was abnormal in 31 patients. The abnormalities were: focal T2 increased signal intensity (13 cases) most often temporal (10 cases), cryptic arteriovenous malformation (4 cases), focal T1 and T2 signal abnormality (4 cases), focal atrophy (2 cases) and multiple abnormal T2 signals scattered in the white matter (8 cases). The site of MRI abnormalities was consistent with electroclinical data in 22 patients, of whom 20 had a temporal lobe epilepsy. Thus MRI proved to be more often abnormal in temporal than in frontal lobe epilepsy (36 p. 100 and 5.9 p. 100 respectively) when the CT scan is normal. However MRI data, particularly focal T2 hypersignals should be confronted to electroclinical and metabolic findings whenever functional surgery is considered.

[First epileptic seizure in the elderly: electroclinical and etiological data in 341 patients]. / Première crise d'épilepsie chez le sujet de plus de 60 ans: données électrocliniques et étiologiques.

This study included 341 subjects aged over 60 years, 174 females and 167 males, (mean age 72-years), who experienced their first epileptic seizure and fulfilled all inclusion criteria over an 8-year period. Data were available from the physical examination, EEG, laboratory tests and CT scan or MRI for all patients. The international classification of epileptic seizures was applied, 41 p.cent of the seizures were generalized and 59 p.cent were partial. Status epilepticus occurred in 8 p.cent of the patients. The EEG recording was contributive to diagnosis or helpful for localizing the epileptic focus in 55 p.cent of the patients. Normal brain imaging was observed in 40 p.cent of the patients. The main etiology was cerebrovascular disease (33 p.cent), acute stroke (27 patients), or more often postvascular epilepsy (87 patients). Other etiologies were degenerative cortical dementia in 7 p.cent of the patients, metabolic and toxic disorders in 11 p.cent, and benign or malignant brain tumors in 6.5 p.cent. Thirty-two percent of the seizures were of unknown origin (cryptogenic seizures). No correlation was found between sex, age, and etiology. An antiepileptic drug treatment was initiated in 77 p.cent of the patients who were given either valproate (43 p.cent), carbamazepine (26 p.cent) or barbiturates (7 p.cent). These findings are in agreement with those reported in the reviewed literature.