Subcortical Brain Lesions Research Articles

Seizure and Myelin Oligodendrocyte Glycoprotein Antibody-Associated Encephalomyelitis in a Retrospective Cohort of Chinese Patients.

Background: Myelin oligodendrocyte glycoprotein (MOG) antibody associated encephalomyelitis is increasingly being considered a distinct disease entity, with seizures and encephalopathy commonly reported. We investigated the clinical features of MOG-IgG positive patients presenting with seizures and/or encephalopathy in a single cohort.Methods: Consecutive patients with suspected idiopathic inflammatory demyelinating diseases were recruited from a tertiary University hospital in Guangdong province, China. Subjects with MOG-IgG seropositivity were analyzed according to whether they presented with or without seizure and/or encephalopathy.Results: Overall, 58 subjects seropositive for MOG-IgG were analyzed, including 23 (40%) subjects presenting with seizures and/or encephalopathy. Meningeal irritation (P = 0.030), fever (P = 0.001), headache (P = 0.001), nausea, and vomiting (P = 0.004) were more commonly found in subjects who had seizures and/or encephalopathy, either at presentation or during the disease course. Nonetheless, there was less optic nerve (4/23, 17.4%, P = 0.003) and spinal cord (6/16, 37.5%, P = 0.037) involvement as compared to subjects without seizures or encephalopathy. Most MOG encephalomyelitis subjects had cortical/subcortical lesions: 65.2% (15/23) in the seizures and/or encephalopathy group and 50.0% (13/26) in the without seizures or encephalopathy group. Cerebrospinal fluid (CSF) leukocytes were elevated in both groups. Subgroup analysis showed that 30% (7/23) MOG-IgG positive subjects with seizures and/or encephalopathy had been misdiagnosed for central nervous system infection on the basis of meningoencephalitis symptoms and elevated CSF leukocytes (P = 0.002).Conclusions: Seizures and encephalopathy are not rare in MOG encephalomyelitis, and are commonly associated with cortical and subcortical brain lesions. MOG-encephalomyelitis often presents with clinical meningoencephalitis symptoms and abnormal CSF findings mimicking central nervous system infection in pediatric and young adult patients.

Basic Neuronavigation Options for Cortical and Subcortical Brain Lesions Surgery

Summary Craniometric points are essential for orienting neurosurgeons in their practice. Understanding the correlations of these points help to manage any pathological lesion located on the cortical surface and subcortically. The brain sulci and gyri should be identified before craniotomy. It is difficult to identify these anatomical structures intraoperatively (after craniotomy) with precision. The main purpose of this study was to collect as much information as possible from the literature and our clinical practice in order to facilitate the placement of craniotomies without using modern neuronavigation systems. Operative reports from the last five years on cranial operations for cortical and subcortical lesions were reviewed. All the craniotomies had been planned, using four methods: detection of craniometric points, computed tomography (CT) scans/topograms, magnetic resonance imaging (MRI) scans/topograms, and intraoperative real-time ultrasonography (USG). Retrospectively, we analyzed 295 cranial operations. Our analysis showed that operating on for cortical lesions, we had frequently used the first and the second method mentioned above (118 patients), while in cases of subcortical lesions, we had used craniometric points, MRI scans/topograms and intraoperative real-time USG as methods of neuronavigation (177 patients). These results show that craniometric points are essential in both neurosurgical procedures.

A clinical study on closing-in in focal brain-damaged individuals

In visuo-constructional assessment, brain-damaged individuals may copy figures near to or superimposed on the model, showing the Closing-in (CI). CI has been largely investigated in dementia, and often ascribed to impairments of the attention/executive abilities (“Attraction hypothesis”). Only a few dated studies investigated frequency of CI in brain-damaged individuals, without clarifying the genesis of the phenomenon. We aimed at testing the “Attraction hypothesis” in 27 individuals with focal frontal cortical or sub-cortical brain lesions by a dual-task experimental paradigm. The participants underwent a neuropsychological battery and a copying task to be performed alone (single task condition), or concurrently with a simple or a complex verbal secondary task (dual-task conditions). CI was found in 66% of frontal-damaged individuals, who scored significantly lower than healthy adults on all neuropsychological measures; brain-damaged individuals showing CI performed worse than frontal-damaged individuals without CI on frontal and visuo-constructional measures. In the dual-task condition with the complex secondary task CI was significantly enhanced, with a weaker tendency to self-correction, in individuals with CI compared to individuals without CI. These findings would confirm that the CI in brain-damaged individuals is related to reduction of attentional resources, consistently with the “Attraction hypothesis”.

Conjugate eye deviation as predictor of acute cortical and subcortical ischemic brain lesions

ObjectivesNon-enhanced computed tomography (NECT) of the brain is used to exclude intracranial hemorrhage in patients who are considered for treatment with tissue plasminogen activator due to stroke symptoms. However, early infarct signs on NECT have low sensitivity for ischemic stroke. It was hypothesized that horizontal conjugate eye deviation (average ocular gaze deviation-OGD >14°) on NECT predicts ischemic brain injury on a second detailed examination. Patients and methodsPatients who underwent brain NECT within three hours after the onset of stroke symptoms and subsequently had brain CT scan with intravenous contrast or MRI were potential participants. OGD was measured from the cross-sectional image including both globes at their maximum diameter. Results73 subjects were studied (mean age 64.2±20.8 years) with a median interval (interquartile range) of 56h (22–109.3h) between NECT and the second examination. On NECT, 24 of 73 (32.9%) subjects had OGD >14°. Of 32 individuals with acute ischemic injury on the second examination, 19 (59.4%) had OGD >14° on NECT. OGD >14° was associated with increased risk of ischemic injury: OR=10.5 (95% confidence interval 3.33–33.9); P=0.002. OGD >14° had significantly higher sensitivity and negative predictive value than early infarct signs on NECT (59.4% vs. 21.9% and 73.5% vs. 59.7%, respectively; P<0.05), and similar specificity and positive predictive value (87.8% vs. 90.2% and 79.2% vs. 63.6%; P>0.05). ConclusionIn the presence of stroke symptoms, average OGD >14° on the initial brain NECT is early predictor of ischemic brain injury.

A simple, safe and effective surface marking and targeting method combined with intraoperative ultrasonography for small subcortical intracranial lesions.

Accurately locating small subcortical brain lesions is very important for maximal surgical resection with minimal neurological damage. Intraoperative MRI has proved to be more precise than ultrasound, it is relatively expensive and is not available in all centers. Herein we describe a new, simple, safe and effective method for determining a small skin incision and craniotomy via skin staples combined with intraoperative ultrasonography to determine the margins, vascularity and residue of the lesion. Thirty-three patients with small subcortical lesions were admitted into the study. The maximum diameter of the lesions ranged between 18 and 30 mm. The depth of the lesion was described as the distance between the cortical surface and most outer point of the lesion. The mean of the depth of the lesions was 10.56 mm ranging between 3.3 and 18.7 mm. Multiple skin staples were used as irremovable skin markers. Before and after dural incision, ultrasound was used to assess the lesion size and location, its relationship with the surrounding tissue and the Doppler function to reveal the blood supply to the lesion. In this study mean craniotomy diameter was 44 mm ranging between 32-55 mm. The location, extent, characteristics and adjacent tissue of the lesion were observed by high frequency ultrasonography during the operation. We describe a simple, safe and effective method for determining a small skin incision and craniotomy combined with intraoperative ultrasound for small subcortical intracranial lesions for health center that does not have intraoperative MRI and navigation systems.

An integrative view of Luria’s perspective on arithmetic problem solving: The two sides of environmental dependency

Introduction: A. R. Luria was the first author to hypothesize that executive dysfunction can lead to specific deficits in arithmetic problem solving, showing that patients’ performance depends on the structure of the tasks. Cummings (1995. Anatomic and behavioral aspects of frontal-subcortical circuits. Annals of the New York Academy of Sciences, 15, 1–13) proposed the term “environmental dependency” to define such behavioral disorders triggered by the characteristics of the test and pointed out also the role of executive impairments. Few studies compare executive functioning and problem solving in brain-damaged patients, and none have examined the question from this point of view. Thus, the main aim of the present paper was to study the relationship between environmental dependency and executive functions. Method: Fifty neurological patients with frontal, subcortical, and posterior brain lesions were compared to 45 matched healthy controls and were divided into two groups (dysexecutive/nondysexecutive) according to their performances on executive tasks. Then, we confronted the results of the two groups on an experimental protocol designed in accordance with Luria’s proposals. We made also comparisons between groups on the basis of lesion location. Results: Our findings indicate a high association between executive functions and environmental dependency, showing that dysexecutive patients’ performances were dependent on task demands. In addition, a specific frontal behavior not associated with executive functions and characterized by the solving of insoluble problems was highlighted. Conclusion: The discussion focused on the interest to take into account the methodological and clinical contributions of environmental dependency. Based on our findings and theoretical arguments, we highlight the need to fractionate this concept.

Usefulness of Preoperative Surgical Simulation with Three-Dimensional Fusion Images for Resection of Cerebral Cavernous Malformations Near Broca's Area.

Treating subcortical brain lesions in or near eloquent areas is challenging not only because lesions must be resected while preserving brain tissue involved in essential functions, but also because lesions often cannot be easily identified from the surface of the brain. Here, we report 2 cases of cerebral cavernous malformations near Broca's area. In both cases, lesions were surgically removed by utilizing three-dimensional fusion images created using preoperative magnetic resonance imaging and computed tomography data. Excisions were completed without any worsening of speech function, and the use of presurgical simulations was found to be useful in the design and execution of the actual operations. The technique described in this report serves as a useful tool in simulating surgical strategies by using brain gyri and sulci as surgical landmarks. Furthermore, in contrast to other intraoperative techniques, this method can aid in shortening the duration of surgery and can help limit damage to eloquent areas of the brain.

Devastating aquaporin-4 and HTLV-1-associated necrotizing encephalopathy

Anti-aquaporin 4 (AQP4) antibody is a marker of neuromyelitis optica (NMO) spectrum diseases, characteristically presenting with myelitis longitudinally extensive transverse myelitis or optic neuritis (ON). While cerebral lesions are recognized, extensive brain involvement and cognitive impairment is rare. We report a case of subacute encephalopathy associated with fulminant subcortical brain lesions. A 19-year-old Jamaican woman reported decreased sensation and power in the left leg, recovering over 2 weeks without medical investigation. Eight months later, she developed painless bilateral visual loss (no perception of light on right, counting fingers on left), treated with intravenous methylprednisolone and plasma exchange. Vision improved gradually to 1/60 (right) and 6/6 (left). Recurrent ON 10 months later reduced acuity to counting fingers bilaterally. With further methylprednisolone, and azathioprine commencement (100 mg/day, low dose because of lymphopenia), acuities improved over 2 months. However, another relapse reduced vision to hand movements bilaterally, necessitating further plasma exchange. Two months thereafter, she developed gait failure, worsening vision, confusion and aggression, severe executive dysfunction, impaired attention, memory and verbal fluency, and suffered a generalized tonic–clonic seizure. There was no perception of light bilaterally, spastic paraparesis and hemisensory loss. With no response to further methylprednisolone and plasma exchange, she was given rituximab (375 mg/kg weekly for 4 weeks). Despite this, 2 weeks later she developed flaccid paraplegia with an extensive cord lesion from cervical to L1 vertebral segments. She remains profoundly disabled; blind, paraplegic, and with impaired comprehension. AQP4-IgG antibody titers were extremely high (maximal level 1:45,000 dilution). Double-stranded DNA antibodies (244 IU/l) and pANCA staining (myeloperoxidase antibody negative) were found. Cerebrospinal fluid (CSF) showed \3 white cells/ll, with normal protein (0.17 g/l). Oligoclonal bands were present in CSF, but not in blood. Antibodies to human T cell lymphotrophic virus (HTLV-1) were present in blood. Viral load was three HTLV-1 DNA copies per 100 peripheral blood mononuclear cells (3 % PBMCs) in blood and 14 % in CSF. MRI revealed T2-hyperintense changes in optic pathways, and numerous periventricular, callosal and juxtacortical white-matter lesions. Over 10 months, scans deteriorated (Fig. 1a, b). A brain biopsy, to exclude other treatable diagnoses, showed features consistent with necrotizing active demyelination (Fig. 1c, e, f; Fig. S1), and absence of AQP4 (Fig. 1d; Figs. S2, S3). Our patient presented with recurrent bilateral ON leading to blindness, and an evolving encephalopathy with necrotizing cerebral white matter destruction. Several features may explain this severity. Electronic supplementary material The online version of this article (doi:10.1007/s00415-012-6651-y) contains supplementary material, which is available to authorized users.

CNS Disease as the Presenting Feature in Four Cases of Juvenile Dermatomyositis (P07.218)

Objective: Presentation of four cases of juvenile dermatomyositis with CNS involvement as the initial feature. Background There are very few case reports in the literature of CNS involvement with JD. There are even fewer cases reported in which the initial presentation of CNS vasculitis and demyelinating disease develops into more recognizable JD. Design/Methods: Four patient cases are presented. Results: We present case reports of four patients who presented with CNS lesions and various degrees of encephalopathy who later progressed to meet clinical criteria for the diagnosis of juvenile dermatomyositis. The first patient we report is a 13 year old male who presented with demyelinating lesions of the spinal cord and optic nerves. He went on to develop weakness of the lower extremities. The second patient, a 6 year old female, initially presented with a viral meningitis, and then went on to develop a myriad of brain lesions on MRI. A third patient, a 9 year old female presented with seizures and encephalopathy. She had both cortical and subcortical brain lesions that showed both inflammation and hemorrhage. The final patient, a 16 year old girl presented with demyelinating lesions of the brain stem and spinal cord. All four of the patients went on to develop proximal muscle weakness, primarily of the lower extremities and had muscle biopsies demonstrating perifascisular atrophy and inflammatory changes consistent with juvenile dermatomyositis. All of these patients responded well to immunosuppressive therapy and made substantial recoveries. Conclusions: These reports should encourage investigation into autoimmune disease in general and JD in particular when cases of CNS disease of unknown etiology present in pediatric patients. There are implications for both prognosis and treatment when the disease course is recognized early. Disclosure: Dr. Lee has nothing to disclose. Dr. Bishop has nothing to disclose. Dr. Vedanarayanan has nothing to disclose.

Bilateral alterations in somatosensory cortical processing in hemiplegic cerebral palsy

In individuals with cerebral palsy (CP), cerebral insults during early development may induce profound reorganization of the motor representation. This study determined the extent of alterations in cortical somatosensory functions in adolescents with hemiplegic CP with subcortical brain lesions. We recorded somatosensory evoked magnetic fields in response to hand area stimulation from eight adolescents with hemiplegic CP (five females and three males; mean age 14y 6mo, SD 2y 3mo) and eight age- and sex-matched healthy comparison adolescents (mean age 15y 4mo, SD 2y 4mo). All participants in the CP group had purely subcortical brain lesions in magnetic resonance images. The somatosensory representation of the affected limb was contralateral (i.e. ipsilesional), but detailed inspection of the evoked responses showed alterations bilaterally. In the primary somatosensory cortex, the representation areas of digits II and V were in both hemispheres closer to each other in participants with CP than in comparison participants [ANOVA main effect group F(1,14) =5.58; p=0.03]. In addition, the morphology of median nerve evoked fields was altered in the participants with CP. In hemiplegic CP, modification of the somatosensory cortical network extends beyond what would be expected based on the unilateral symptoms and the anatomical lesion. Further understanding of the functional alterations in the sensorimotor networks may aid in developing more precisely designed rehabilitation strategies.

A contribution to the study of environmental dependency phenomena: The social hypothesis

Environmental dependency phenomena refer to the symptoms initially described by Lhermitte (1983, 1984) under the terms of “utilization behavior” and “imitation behavior”. These clinical signs are linked to essential notions such as free-will and human autonomy, and seem to be specific of the frontal pathology. Surprisingly, few studies have addressed these symptoms and inconsistent definitions are available. To investigate the theoretical and clinical definitions of environmental dependency phenomena, three groups of neurological patients (n=60) with frontal, subcortical, and posterior brain lesions were compared. Clinically, our findings help to rehabilitate the definitions of Lhermitte (1983, 1984) and challenge the classical interpretation in terms of an executive control deficit. The frontal specificity of the disorders and the lack of relation between executive/behavioral deficits were supported. The right orbitofrontal cortex seems particularly involved in environmental dependency. These results offer some evidences for differentiate two historical concepts of neuropsychology, namely the “frontal” and “dysexecutive” syndromes. A new interpretation of environmental dependency phenomena is provided which could be helpful to orient the neuropsychology of frontal syndrome.

Lateral Cord Stimulation Decreases Spastic Electromyographic Spreading: Responses in a Brain-Damaged Pig Preparation

Objective. The aim of our work was to investigate whether lateral stimulation of the spinal cord, lateral cord stimulation (LCS), results in inhibition of the spastic phenomena of upper motor lesions in an animal model. Methods. This study was conducted using an animal model consisting of surgically brain damaged pigs subjected to unilateral cortical and subcortical brain lesions. A double laminectomy at cervical (C3-C4) and lumbar (L3-L6) was performed, and spastic thresholds of abnormal electromyographic responses, disseminated to adjacent segments, facilitated by spinal liberation, and produced by extradural electrical stimulation of the fourth lumbar root, were measured before and after cervical stimulation of the LCS. The variable studied was the minimal amount of current of LCS necessary to abolish electromyographic responses in the L7 myotome, away from the stimulated L4 nerve root. Results. Experiments in 12 animals showed a significant increase of threshold after LCS, with a marked posteffect, signaling a less abnormal threshold. Conclusions. This experiment demonstrated that LCS produces threshold increases to abolish abnormally propagated electromyographic evoked responses induced by the electrical stimulation of the fourth lumbar root in pigs with experimental cortical and subcortical brain lesions.

Intraoperative localization of subcortical brain lesions

Some brain tumors may grow immediately beneath the cortical surface without distorting its appearance. Intraoperative image guidance promotes safe resection. We have developed MRI-based corticotopography (MRI-bct), to localize lesions during surgery, using simple, non-dedicated equipment, to match a three-dimensional reconstruction with the corresponding appearance of the brain cortex. Forty-six patients underwent resection of subcortical brain lesions, aided by MRI-bct. The lesions had a maximum diameter less than 3 cm, were subcortical but no deeper than the floor of the nearest cerebral sulcus. Each patient had a volumetric MRI scan with and without contrast administration. Data sets were transferred to a laptop personal computer and processed using a rendering software. At operation, the three-dimensional model of the brain, including a surface overlay of the lesion, was matched to the exposed brain surface. After its exact relationship with the overlying sulcal pattern was defined, the lesion was localized and resected. In selected patients, the procedure was coupled with functional brain mapping. Data processing took from 10 to 15 min and could be done whenever convenient before operation. Surface matching between the surgical field and the reformatted MRI always required less than 5 min and was done near the operating table. In all patients, the lesion was identified at the first attempt, through a small corticotomy, regardless of the brain shift after dural opening. MRI-bct is a practical, time-saving neuronavigational aid ideal for localizing superficial lesions underlying the cerebral cortex because it unmistakably characterizes the adjacent sulcal anatomy.

A new EAE model of brain demyelination induced by intracerebroventricular pertussis toxin

Experimental autoimmune encephalomyelitis (EAE) is a primary animal model of multiple sclerosis (MS). MS predominantly presents with evidence of lesions in the subcortical periventricular white matter regions of the brain. Research into the pathogenesis of the demyelinating lesions in the brain has been hampered by the fact that conventional models of EAE present with progressive ascending paralysis which recapitulates mainly the spinal cord lesions of multiple sclerosis. There is little evidence of brain involvement. Systemic administration of pertussis toxin (PTx) has been shown to induce the proinflammatory cascade of TGF-β, IL-6, and Th17 in the central nervous system, which recently has been identified as essential in the development of EAE. To determine whether intracerebroventricular (icv) administration of PTx would result in subcortical periventricular demyelinating lesions in the brain, we examined the effect in a MOG induced EAE model. We found that icv PTx induced subcortical periventricular brain lesions that resemble the pathologic demyelinating lesions of MS. Moreover, icv PTx induced Th17 infiltration and increased expression of cytokines IL-6 and TGF-β. We thus generated a highly reproducible model with remarkable histological similarities to the predominant demyelinating brain lesions seen in MS.

Resection of a left insular cavernoma aided by a simple navigational tool

The management of cavernous malformations of the brain is markedly influenced by the location of the lesions themselves. In the last decade, resection of cavernomas arising in the dominant insular lobe has been deemed safe only with the guidance of neuronavigation. Most navigation equipment, however, shares some minor drawbacks, including costs, longer operating time, and a variable loss of accuracy due to intraoperative brain shift. In this paper the authors present the case of a left dominant insular cavernoma that was successfully removed using a novel form of navigation that they call magnetic resonance imaging-based corticotopography. This technique, which is unaffected by the brain shift phenomenon, provided a simple and inexpensive alternative to standard neuronavigation. Selected cases of subcortical brain lesions could be conveniently approached using the same technique.

Transsulcal microsurgical approach for subcortical small brain lesions: technical note

We describe a transsulcal microsurgical approach for removal of small subcortical brain lesions, guided by frameless stereotaxy. This technique of simultaneous stereotactic localization of the subcortical lesion and its adjacent sulcus, before surgical approach, results in optimal surgical planning, leading to minimal brain tissue loss and excellent surgical outcome.

Recruitment and sequencing of different degrees of freedom during pointing movements involving the trunk in healthy and hemiparetic subjects.

Previous studies have shown that in neurologically normal subjects the addition of trunk motion during a reaching task does not affect the trajectory of the arm endpoint. Typically, the trunk begins to move before the onset and continues to move after the offset of the arm endpoint displacement. This observation shows that the potential contribution of the trunk to the motion of the arm endpoint toward a target is neutralized by appropriate compensatory movements of the shoulder and elbow. We tested the hypothesis that cortical and subcortical brain lesions may disrupt the timing of trunk and arm endpoint motion in hemiparetic subjects. Eight hemiparetic and six age-matched healthy subjects were seated on a stool with the right (dominant) arm in front of them on a table. The tip of the index finger (the arm endpoint) was initially at a distance of 20 cm from the midline of the chest. Wrist, elbow, and upper body positions as well as the coordinates of the arm endpoint were recorded with a three-dimensional motion analysis system (Optotrak) by infrared light-emitting diodes placed on the tip of the finger, the styloid process of the ulna, the lateral epicondyle of the humerus, the acromion processes bilaterally, and the sternal notch. In response to a preparatory signal, subjects lifted their arm 1-2 cm above the table and in response to a "go" signal moved their endpoint as fast as possible from a near to a far target located at a distance of 35 cm and at a 45 degrees angle to the right or left of the sagittal midline of the trunk. After a pause (200-500 ms) they moved the endpoint back to the near target. Pointing movements were made without trunk motion (control trials) or with a sagittal motion of the trunk produced by means of a hip flexion or extension (test trials). In one set of test trials, subjects were required to move the trunk forward while moving the arm to the target ("in-phase movements"). In the other set, subjects were required to move the trunk backward when the arm moved to the far target ("out-of-phase movements"). Compared with healthy subjects, movements in hemiparetic subjects were segmented, slower, and characterized by a greater variability and by deflection of the trajectory from a straight line. In addition, there was a moderate increase in the errors in movement direction and extent. These deficits were similar in magnitude whether or not the trunk was involved. Although hemiparetic subjects were able to compensate the influence of the trunk motion on the movement of the arm endpoint, they accomplished this by making more segmented movements than healthy subjects. In addition, they were unable to stabilize the sequence of trunk and arm endpoint movements in a set of trials. It is concluded that recruitment and sequencing of different degrees of freedom may be impaired in this population of patients. This inability may partly be responsible for other deficits observed in hemiparetic subjects, including an increase in movement segmentation and duration. The lack of stereotypic movement sequencing may imply that these subjects had deficits in learning associated with short-term memory.

Structural and Functional Meta-analytic Evidence for Fronto-subcortical System Deficit in Progressive Supranuclear Palsy

Meta-analytic methods were used to determine the most sensitive indexes to fronto-subcortical deficit in progressive supranuclear palsy (PSP) and to further characterize the neurocognitive and related features of PSP that can provide a basis of comparison to other disorders with prominent subcortical brain lesions. Studies dating back to 1984 were gathered and calibrated to compare the neuropsychological, neuroimaging, and neurophysiological test results from 229 patients with PSP, and 357 healthy controls. The tests most sensitive to fronto-subcortical deficit in PSP were mostly neuropsychological measures that include such tests as the Stroop Task, Trail Making Test Part A, and Purdue pegboard performance. We conclude that although neuropsychological measures may be most sensitive to deficits in PSP, they are also less specific and valid indicators of fronto-subcortical brain system integrity.

Seizures in neurofibromatosis 1

Neurofibromatosis 1 is a common, genetically transmitted neurodevelopmental disorder with a high potential to cause subcortical focal brain lesions. Although seizures occasionally complicate neurofibromatosis 1, they have not been characterized adequately in the disease. Other phacomatoses with attendant subcortical focal brain lesions have been associated with an evolution from generalized to focal-onset epilepsy. This evolution may be related to the cortical dysplasias that also appear in such disorders. Cortical dysplasias, although occasionally found in neurofibromatosis 1 epileptic patients, are not as frequent as in other phacomatoses. The authors retrospectively screened 499 neurofibromatosis 1 patients for the prevalence and etiology of seizures, their response to therapy, and the evolution of seizure type over time. The prevalence of epileptic seizures (4.2%) was about twice the prevalence in the general population. There were no significant cortical dysplasias identified radiographically nor was there a relationship among the presence of subcortical focal brain lesions and seizure type, response to treatment, or evolution of epilepsy in the neurofibromatosis 1 population. The authors’ data do not suggest an ontogeny of epilepsy in neurofibromatosis 1 that is different from the general epileptic population.

Random motor generation in a finger tapping task: influence of spatial contingency and of cortical and subcortical hemispheric brain lesions

OBJECTIVETo test the hypothesis that, during random motor generation, the spatial contingencies inherent to the task would induce additional preferences in normal subjects, shifting their performances farther from randomness. By...