Jeffrey D. Jirsch

High-frequency intracerebral EEG activity (100-500 Hz) following interictal spikes

Summary:  Purpose: High‐frequency activity has been recorded with intracerebral microelectrodes in epileptic patients and related to seizure genesis. Our goal was to analyze high‐frequency activity recorded with electroencephalograph (EEG) macroelectrodes during the slow wave immediately following interictal spikes, given the potential importance of this presumed hyperpolarization in transforming spikes into seizures.

High frequency oscillations (80–500 Hz) in the preictal period in patients with focal seizures

Purpose:  Intracranial depth macroelectrode recordings from patients with focal seizures demonstrate interictal and ictal high frequency oscillations (HFOs, 80–500 Hz). These HFOs are more frequent in the seizure‐onset zone (SOZ) and reported to be linked to seizure genesis. We evaluated whether HFO activity changes in a systematic way during the preictal period.

Functional organization of human visual cortex in occipital polymicrogyria.

Polymicrogyrias (PMG) are cortical malformations resulting from developmental abnormalities. In animal models PMG has been associated with abnormal anatomy, function, and organization. The purpose of this study was to describe the function and organization of human polymicrogyric cortex using functional magnetic resonance imaging. Three patients with epilepsy and bilateral parasagittal occipital polymicrogyri were studied. They all had normal vision as tested by Humphrey visual field perimetry. The functional organization of the visual cortex was reconstructed using phase‐encoded retinotopic mapping analysis. This method sequentially stimulates each point in the visual field along the axes of a polar‐coordinate system, thereby reconstructing the representation of the visual field on the cortex. We found normal cortical responses and organization of early visual areas (V1, V2, and V3/VP). The locations of these visual areas overlapped substantially with the PMG. In five out of six hemispheres the reconstructed primary visual cortex completely fell within polymicrogyric areas. Our results suggest that human polymicrogyric cortex is not only organized in a normal fashion, but is also actively involved in processing of visual information and contributes to normal visual perception. Hum Brain Mapp 2007.

Sensorimotor organization in double cortex syndrome.

Subcortical band heterotopia is a diffuse malformation of cortical development related to pharmacologically intractable epilepsy. On magnetic resonance imaging (MRI), patients with “double cortex” syndrome (DCS) present with a band of heterotopic gray matter separated from the overlying cortex by a layer of white matter. The function and connectivity of the subcortical heterotopic band in humans is only partially understood. We studied six DCS patients with bilateral subcortical band heterotopias and six healthy controls using functional MRI (fMRI). In controls, simple motor task elicited contralateral activation of the primary motor cortex (M1) and ipsilateral activation of the cerebellum and left supplementary motor area (SMA). All DCS patients showed task‐related contralateral activation of both M1 and the underlying heterotopic band. Ipsilateral motor activation was seen in 4/6 DCS patients. Furthermore, there were additional activations of nonprimary normotopic cortical areas. The sensory stimulus resulted in activation of the contralateral primary sensory cortex (SI) and the thalamus in all healthy subjects. The left sensory task also induced a contralateral activation of the insular cortex. Sensory activation of the contralateral SI was seen in all DCS patients and secondary somatosensory areas in 5/6. The heterotopic band beneath SI became activated in 3/6 DCS patients. Activations were also seen in subcortical structures for both paradigms. In DCS, motor and sensory tasks induce an activation of the subcortical heterotopic band. The recruitment of bilateral primary areas and higher‐order association normotopic cortices indicates the need for a widespread network to perform simple tasks. Hum Brain Mapp, 2005.

Status Epilepticus Presenting in a Patient with Neurosyphilis and a Previously Asymptomatic Arachnoid Cyst

To the Editor: Primavera et al. (1) described a series of four patients with neurosyphilis with status epilepticus (SE) as the first manifestation of their infection. We report a similar presentation in a man with a previously asymptomatic arachnoid cyst. A 44-year-old man had been previously healthy. For two months prior to his admission, relatives noted mild word-finding difficulties with a slight deterioration in verbal fluency. The evening before his admission he had loss of dexterity in his right hand while using chopsticks at a restaurant. Several hours later, he was found convulsing by his wife. There was no history of previous seizures, head trauma, or serious infections (including syphilis-associated skin lesions). On arrival to the emergency department, he had been

Screening for depression in a tertiary epilepsy clinic.

Symptoms of depression are common in patients with epilepsy with a reported prevalence of as high as 54%1. The fact that depression is a strong predictor of quality of life1 highlights the importance of developing effective screening tools to assist in the diagnosis of depression in the epilepsy outpatient clinic setting. Gilliam et al have reported that the Neurologic Disorders Depression Inventory in Epilepsy (NDDI-E) is an effective screening tool to detect depression in patients with epilepsy with NDDI-E scores >15 associated with a positive predictive value (PPV) of 62% for major depressive episode (MDE)2. Other researchers have also demonstrated high PPV for the NDDI-E3, however, the internal reliability of the NDDI-E has not been previously reported. While the replication of validation studies suggests that the NDDI-E is an effective tool to screen for MDE, the results are surprising given the considerable differences in phraseology between the NDDI-E and the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Test Revision (DSM-IV-TR)4. Specifically in order to make a DSMIV-TR diagnosis of MDE, a patient must respond affirmatively to experiencing symptoms “most of the day, nearly every day” for five of nine questions while for the NDDI-E a positive score (>15) is possible without any response being in the “always or often” category (i.e. responding “sometimes” to all questions results in an NDDI-E score of 18). The purpose of this study was to evaluate the predictive value of the NDDI-E for MDE in an adult tertiary epilepsy clinic setting. As well, the internal reliability of the NDDI-E was also evaluated.

Erratum: High-frequency intracerebral EEG activity (100-500 Hz) following interictal spikes (Epilepsia (2006) 47, (1465-1476))

FIG. 8. Schematic representation of the most frequent patterns of changes. The illustration shows the region of the temporal lobe but similar results were found in other regions. Each rectangle represents one electrode bundle (top, amygdala; middle, hippocampus; lower, posterior hippocampus, or parahippocampus). The changes in different frequency bands are represented by sinusoids at different frequencies (see box on figure). The lengths of the sinusoids indicate the spatial extent of the changes in the bundle. The green shaded region represents the extent of the spike in each bundle. Darker green areas indicate the locations where the spikes are most prominent. (A) Widespread increase in subgamma power represented by the long red sinusoid and spatially graded decrease in gamma, HF, and VHF, represented by the progressively shorter blue sinusoids. The VHF decrease is only present in the region where the spike is largest (dark green shading); (B) A different pattern was often seen in the temporal lobe, with a decrease in high frequencies in the hippocampus but an increase in the amygdala.