Marie Atkinson

Multimodality language mapping in patients with left-hemispheric language dominance on Wada test

OBJECTIVE We determined the utility of electrocorticography (ECoG) and stimulation for detecting language-related sites in patients with left-hemispheric language-dominance on Wada test. METHODS We studied 13 epileptic patients who underwent language mapping using event-related gamma-oscillations on ECoG and stimulation via subdural electrodes. Sites showing significant gamma-augmentation during an auditory-naming task were defined as language-related ECoG sites. Sites at which stimulation resulted in auditory perceptual changes, failure to verbalize a correct answer, or sensorimotor symptoms involving the mouth were defined as language-related stimulation sites. We determined how frequently these methods revealed language-related sites in the superior-temporal, inferior-frontal, dorsolateral-premotor, and inferior-Rolandic regions. RESULTS Language-related sites in the superior-temporal and inferior-frontal gyri were detected by ECoG more frequently than stimulation (p < 0.05), while those in the dorsolateral-premotor and inferior-Rolandic regions were detected by both methods equally. Stimulation of language-related ECoG sites, compared to the others, more frequently elicited language symptoms (p < 0.00001). One patient developed dysphasia requiring in-patient speech therapy following resection of the dorsolateral-premotor and inferior-Rolandic regions containing language-related ECoG sites not otherwise detected by stimulation. CONCLUSIONS Language-related gamma-oscillations may serve as an alternative biomarker of underlying language function in patients with left-hemispheric language-dominance. SIGNIFICANCE Measurement of language-related gamma-oscillations is warranted in presurgical evaluation of epileptic patients.

Clinical significance and developmental changes of auditory-language-related gamma activity

OBJECTIVE We determined the clinical impact and developmental changes of auditory-language-related augmentation of gamma activity at 50-120 Hz recorded on electrocorticography (ECoG). METHODS We analyzed data from 77 epileptic patients ranging 4-56 years in age. We determined the effects of seizure-onset zone, electrode location, and patient-age upon gamma-augmentation elicited by an auditory-naming task. RESULTS Gamma-augmentation was less frequently elicited within seizure-onset sites compared to other sites. Regardless of age, gamma-augmentation most often involved the 80-100 Hz frequency band. Gamma-augmentation initially involved bilateral superior-temporal regions, followed by left-side dominant involvement in the middle-temporal, medial-temporal, inferior-frontal, dorsolateral-premotor, and medial-frontal regions and concluded with bilateral inferior-Rolandic involvement. Compared to younger patients, those older than 10 years had a larger proportion of left dorsolateral-premotor and right inferior-frontal sites showing gamma-augmentation. The incidence of a post-operative language deficit requiring speech therapy was predicted by the number of resected sites with gamma-augmentation in the superior-temporal, inferior-frontal, dorsolateral-premotor, and inferior-Rolandic regions of the left hemisphere assumed to contain essential language function (r(2) = 0.59; p = 0.001; odds ratio = 6.04 [95% confidence-interval: 2.26-16.15]). CONCLUSIONS Auditory-language-related gamma-augmentation can provide additional information useful to localize the primary language areas. SIGNIFICANCE These results derived from a large sample of patients support the utility of auditory-language-related gamma-augmentation in presurgical evaluation.

Improving safety outcomes in the epilepsy monitoring unit.

Long term video electroencephalography (EEG) in epilepsy monitoring units (EMU) is used to diagnose and treat patients with epilepsy. Injury occurs in the EMU, including reports of death. No standardized patient safety protocols exist. Our objective is to determine the frequency and contributing factors to injury in the EMU. We reviewed medical records and video EEG of patients with epilepsy admitted to our EMU from December 1, 2008 to June 1, 2009. Data was collected on seizure type, onset, length, and frequency. Seizure related falls, injury, and adverse events were recorded. Data regarding the physical environment and treatment during seizures were analyzed too. 20 patients with 170 seizures were collected. Of the 170 total seizures captured, only 1 injury (0.6%) and 6 falls occurred (3.5%). 5 of the 6 falls were related to patients being ambulatory. No seizures resulted in prolonged stay. Of the 170 seizures captured, other adverse events included 1 status epilepticus (0.6%), 2 postictal aggression (1.2%), 4 objects in mouth (2.4%), 14 ambulatory at seizure onset (8.2%) and 5 postictal ambulation from bed (2.9%). Staff responded to 69 out of 170 seizures (40.6%). Of the 101 seizures without staff response, 57 seizures were electrographic without seizure detection software or push button activation. Falls and adverse events that can lead to injury occur in the EMU, yet the degree of actual injury is minimal. To improve safety outcomes, standardized protocols with appropriate outlined nursing care and procedures for continuous monitoring of patients by staff need to be employed.

Evaluating reverse speech as a control task with language-related gamma activity on electrocorticography

Reverse speech has often been used as a control task in brain-mapping studies of language utilizing various non-invasive modalities. The rationale is that reverse speech is comparable to forward speech in terms of auditory characteristics, while omitting the linguistic components. Thus, it may control for non-language auditory functions. This finds some support in fMRI studies indicating that reverse speech resulted in less blood-oxygen-level-dependent (BOLD) signal intensity in perisylvian regions than forward speech. We attempted to externally validate a reverse speech control task using intracranial electrocorticography (ECoG) in eight patients with intractable focal epilepsy. We studied adolescent and adult patients who underwent extraoperative ECoG prior to resective epilepsy surgery. All patients received an auditory language task during ECoG recording. Patients were presented 115 audible question stimuli, including 30 reverse speech trials. Reverse speech trials more strongly engaged bilateral superior temporal sites than did the corresponding forward speech trials. Forward speech trials elicited larger gamma-augmentation at frontal lobe sites not attributable to sensorimotor function. Other temporal and frontal sites of significant augmentation showed no significant difference between reverse and forward speech. Thus, we failed to validate reported evidence of weaker activation of temporal neocortices during reverse compared to forward speech. Superior temporal lobe engagement may indicate increased attention to reverse speech. Reverse speech does not appear to be a suitable task for the control of non-language auditory functions on ECoG.

Safety considerations in the epilepsy monitoring unit for psychogenic nonepileptic seizures

Injury occurs in epilepsy monitoring units (EMUs) to patients with epileptic seizures (ES); however, there are limited data regarding the safety concerns of patients with psychogenic nonepileptic seizures (PNES) being monitored in EMUs. We reviewed EMU records from 116 PNES and compared them to 170 ES. Three falls (2.6%) occurred in PNES without injury compared to 6 falls (3.5%) in ES with 1 injury, a facial hematoma. Of the 9 total falls, 8 patients were ambulatory during their events. Several adverse incidents occurred for both groups. Of the PNES without staff response, 30 of 39 were due to PNES being less than 60s in duration, and 16 of 39 involved lack of push-button activation to alert the staff. For the ES group, 57 of 101 were due to electrographic seizures without seizure detection software or push-button activation. Similar safety protocols should be administered while monitoring these patients regardless of seizure type.

Cerebral Infarct in Pediatric Neuro-Behçet's Disease

Behçets disease is a multisystem inflammatory vasculitic disorder with a chronic course for which the etiology is unknown. The central nervous system can be affected in 5% to 30% of all Behçet patients, yet it has been rarely reported in children or in Western countries. We describe a 14-year-old girl with Behçets disease that presented initially as a cerebral infarct without venous sinus thrombosis.

Paradoxical imaging findings in cerebral gliomas

Gliomas represent approximately one-third of all intracranial tumors in adults and commonly present clinically with seizures. We report two seizure patients with paradoxical imaging findings on preoperative grading of their cerebral gliomas. A 53-year-old man with a history of temporal lobe epilepsy originating from a mass in the right medial temporal region (patient 1) and a 44-year-old man with a history of predominantly left sided sensory seizures with a mass in the right posterior parietal region (patient 2) underwent presurgical evaluation including MRI and glucose PET, followed by surgery to remove cerebral tumors associated with seizure onset. Preoperatively, patient 1 had a homogenous non-enhancing lesion on MRI and hypometabolism on PET imaging, suggesting a low-grade tumor. Postoperative histopathology was consistent with a glioblastoma multiforme (grade IV). Patient 2 had a heterogeneous lesion with cyst formation, edema, and contrast enhancement on preoperative MRI imaging, and interictal hypermetabolism on PET scan, thus suggesting a high-grade tumor. Postoperative histopathology was consistent with an oligodendroglioma (grade II) without anaplastic features. We conclude preoperative grading of cerebral gliomas may be inaccurate occasionally even in cases with concordant structural and functional imaging findings. This should be considered when counseling patients.

Transient shivering during Wada test provides insight into human thermoregulation

Purpose:  Some patients with pharmacoresistant epilepsy undergoing the Wada test experience transient shivering. The purpose of this study was to investigate various clinical and radiographic characteristics of these individuals to delineate underlying mechanisms of this phenomenon.

Refractory status epilepticus secondary to CNS vasculitis, a role for epilepsy surgery

Central nervous system (CNS) vasculitis is a rare group of disorders that affect vessels of the brain parenchyma and meninges. It presents with headache, cognitive changes, or seizures, yet without aggressive management, it carries a high degree of morbidity and mortality. Refractory status epilepticus (SE) has been reported with CNS vasculitis. Patients are treated with immunosuppression, antiepileptic drugs (AED), and anesthetic agents. Outcomes are usually poor. Epilepsy surgery for refractory partial SE has succeeded in patients. We present a comparison of two patients with refractory partial SE due to CNS vasculitis. One patient was treated medically and died, while the other underwent epilepsy surgery to remove the epileptic focus along with medical therapy and the patient had substantial recovery. We describe clinical, electrophysiological, pathological, and treatment features of both patients and discuss rationale for surgical intervention. This is the first case report of the use of epilepsy surgery for the treatment of refractory SE associated with CNS vasculitis.