Mirror movements following cortical resection of polymicrogyria in a child with intractable epilepsy

Surgical treatment of polymicrogyria-related epilepsy

OBJECTIVE

The role of resective surgery in the treatment of polymicrogyria (PMG)-related focal epilepsy is uncertain. Our aim was to retrospectively evaluate the seizure outcome in a consecutive series of patients with PMG-related epilepsy who received, or did not receive, surgical treatment, and to outline the clinical characteristics of patients who underwent surgery.

METHODS

We evaluated 64 patients with epilepsy associated with magnetic resonance imaging (MRI)-documented PMG. After presurgical evaluation, 32 patients were excluded from surgical treatment and 32 were offered surgery, which was declined by 8 patients. Seizure outcome was assessed in the 40 nonsurgical and 24 surgical patients.

RESULTS

Of 40 nonsurgical patients, 8 (20%) were seizure-free after a mean follow-up of 91.7 ± (standard deviation) 59.5 months. None of the eight patients who declined surgical treatment was seizure-free (mean follow-up: 74.3 ± 60.6 months). These seizure outcomes differ significantly (p = 0.000005 and p = 0.0003, respectively) from that of the 24 surgical patients, 18 of whom (66.7%) were Engel's class I postoperatively (mean follow-up: 66.5 ± 54.0 months). Of the eight patients excluded from surgery for seizure control at first visit, two had seizure recurrence at last contact. At last contact, antiepileptic drugs (AEDs) had been withdrawn in 6 of 24 surgical and in one of 40 nonsurgical cases (p = 0.0092).

SIGNIFICANCE

The present study indicates that, at least in a subset of adequately selected patients with PMG-related epilepsy, surgery may provide excellent seizure outcomes. Furthermore, it suggests that surgery is superior to AEDs for achieving seizure freedom in these cases.

Mirror movements in progressive hemifacial atrophy

Mirror movements are simultaneous, involuntary, identical movements occurring during contralateral voluntary movements. These movements are considered as soft neurologic signs seen uncommonly in clinical practice. The mirror movements are described in various neurological disorders which include parkinsonism, cranio veretebral junction anamolies, and hemiplegic cerebral palsy. These movements are intriguing and can pose significant disability. However, no such observation regarding mirror movements in progressive hemifacial atrophy have been reported previously. We are reporting a teenage girl suffering from progressive hemifacial atrophy and epilepsy with demonstrable mirror movements in hand.

Polymicrogyria-associated epilepsy: a multicenter phenotypic study from the Epilepsy Phenome/Genome Project

PURPOSE

Polymicrogyria (PMG) is an epileptogenic malformation of cortical development. We describe the clinical epilepsy and imaging features of a large cohort with PMG-related epilepsy.

METHODS

Participants were recruited through the Epilepsy Phenome/Genome Project, a multicenter collaborative effort to collect detailed phenotypic data on individuals with epilepsy. We reviewed phenotypic data from participants with epilepsy and PMG.

KEY FINDINGS

We identified 87 participants, 43 female and 44 male, with PMG and epilepsy. Median age of seizure onset was 3 years (range <1 month to 37 years). Most presented with focal epilepsy (87.4%), some in combination with seizures generalized from onset (23.0%). Focal seizures with dyscognitive features were most common (54.3%). Of those presenting with generalized seizure types, infantile spasms were most prevalent (45.2%). The most common topographic pattern was perisylvian PMG (77.0%), of which the majority was bilateral (56.7%). Generalized PMG presented with an earlier age of seizure onset (median age of 8 months) and an increased prevalence of developmental delay prior to seizure onset (57.1%). Of the unilateral, and asymmetric bilateral groups where PMG was more involved in one hemisphere, the majority (71.4%) of participants had seizures that lateralized to the same hemisphere as the PMG or the hemisphere with greater involvement.

SIGNIFICANCE

Participants with PMG had both focal and generalized onset of seizures. Our data confirm the involvement of known topographic patterns of PMG and suggest that more extensive distributions of PMG present with an earlier age of seizure onset and increased prevalence of developmental delay prior to seizure onset.

Seckel syndrome with asymptomatic tonsillar herniation and congenital mirror movements

Seckel syndrome is a rare genetic disorder of recessive inheritance characterized by prenatal-onset growth retardation, abnormally small head, varying degrees of mental retardation and an unusual ''beak-like'' protrusion of the nose. Additionally, it is associated with multiple organ system anomalies, including that of the central nervous system. An 8-year-old male child with typical features of Seckel syndrome and asymptomatic cerebellar tonsillar herniation diagnosed by magnetic resonance imaging associated with congenital mirror movements of the upper extremities is described. The child, additionally, had agenesis of the corpus callosum. Previously reported central nervous system anomalies associated with congenital mirror movements include corpus callosal agenesis and cranio-vertebral anomalies, both of which were present in this child. To the best of our knowledge, this is the first report of congenital mirror movements occurring in association with Seckel syndrome.

Intralesional recordings and epileptogenic zone in focal polymicrogyria

PURPOSE

Polymicrogyria (PMG) is recognized as an epileptogenic lesion but few data concerning organization of the epileptogenic zone (EZ) are available.

METHODS

We analyzed the distribution of the EZ according to Stereo-EEG (SEEG) with intralesional recordings in four patients evaluated for intractable partial epilepsy associated with focal unilateral PMG, involving the posterior temporal region in two, the perisylvian area in one and the temporoparietal junction in the other. All had ictal scalp EEG, high-resolution structural and functional MRI, fluorodeoxyglucose positron emission tomography (FDG-PET), and SEEG. For each patient, several depth electrodes were implanted both within the PMG and in extralesional areas.

RESULTS

In three patients, the PMG displayed high-frequency spiking activity. However, interictal and ictal recordings demonstrated a large epileptogenic network, which was more widespread than the PMG, including the mesial temporal structures in two. In another patient, interictal spiking and seizure onset site were located within the hippocampus and outside of the PMG, although it was rapidly involved during seizure spread. Overall, EZ was considered to be larger than the PMG in all patients although hypometabolic areas detected by PET were concordant with EZ. Three patients underwent extensive surgery including the PMG and are seizure free with a follow-up >2 years.

DISCUSSION

Although intralesional recordings demonstrated intrinsic epileptogenicity in PMG, our data provide evidence that unilateral focal PMG belongs to a large epileptogenic network extending beyond the MRI lesion. SEEG may be helpful for planning surgery with favorable outcome, providing large resections are feasible, even in apparently focal PMG.

Postsynaptic currents prior to onset of epileptiform activity in rat microgyria

Structural malformations of the cortex, arising as a result of genetic mutation or injury during development are associated with dyslexia, epilepsy, and other neurological deficits. We have used a rat model of a microgyral malformation to examine mechanisms of epileptogenesis. Our previous studies showed that the frequency of miniature excitatory postsynaptic currents (mEPSCs) recorded in neocortical layer V pyramidal neurons is increased in malformed cortex at a time when field potential epileptiform events can be evoked. Here we show that the increase occurs at an age before onset of cortical epileptiform activity and at a time when the frequency of mEPSCs in control layer V pyramidal neurons is stable. An increase in the frequency of spontaneous (s)EPSCs in layer V pyramidal neurons of malformed cortex occurs earlier than that for mEPSCs, suggesting that there may additionally be alterations in intrinsic properties that increase the excitability of the cortical afferents. Frequencies of EPSC bursts and late evoked activity were also increased in malformed cortex. These results suggest that a hyperinnervation of layer V pyramidal neurons by excitatory afferents occurs as an active process likely contributing to subsequent development of field epileptiform events.

Surgical treatment of polymicrogyria with advanced radiologic and neurophysiologic techniques

INTRODUCTION

Coexistence of multiple seizure types, inclusion of the motor cortex in the epileptogenic zone, and poor delimitation of the abnormal cortex make most patients with polymicrogyria (PMG) unlikely candidates for epilepsy surgery (Guerrini R et al., Epilepsy and malformations of the cerebral cortex in Epileptic syndromes in infancy, childhood and adolescence, 2005).

CASE REPORT

We present here a child with frontal PMG and intractable epilepsy evaluated with advanced magnetic resonance imaging (MRI) and neurophysiologic techniques. Diffusion tensor imaging and fiber tractography showed severe involvement of neighboring white matter tracts besides the cortex. The evaluation also included functional MRI, chronic subdural electroencephalogram monitoring, and intra-operative motor mapping. The patient had a decrease in seizure frequency and an increase in his developmental skills after the surgery.

CONCLUSION

Advanced neuroradiologic and neurophysiologic techniques are required to provide an effective and safe resection of the epileptogenic cortex in cortical dysplasias.