Lesion localization in periodic lateralized epileptiform discharges: gray or white matter.

We analyzed the results of neuroimaging studies in patients with periodic lateralized epileptiform discharges (PLEDs) or bilateral independent periodic lateralized epileptiform discharges (BIPLEDs) for localization of lesions in gray or white matter to determine if "cortical isolation" is a critical mechanism in the pathogenesis of this phenomena. We assessed 32 patients who had undergone computed tomography (CT) exclusively and 8 patients who had undergone magnetic resonance imaging (MRI) with or without CT. The superior resolution necessary for adequate lesion localization allowed use of only the MRI scans from the 8 patients. Six patients had scans with cortical and subcortical gray and white matter lesions, and 1 patient had a cortical gray matter lesion only. One patient had an indeterminate scan. No patient had white matter lesions only. Our findings in patients with PLEDs and BIPLEDs correlate with postmortem data in patients with generalized periodic EEG patterns that show consistent localization of lesions in the gray matter. These findings do not support cortical isolation as the critical or sole mechanism in PLEDs or BIPLEDs.

Lower brain-stem origin of the median nerve N18 potential.

A patient undergoing intraoperative median nerve somatosensory evoked potential (MSEP) and brain-stem auditory evoked response (BAER) monitoring showed changes during basilar artery aneurysm clipping. There was loss of the BAER wave V, with preservation of waves I and III. Simultaneously, there also was loss of the MSEP N20 potential, with preservation of the N18, N13 and Erb's point potentials. The patient died and autopsy showed an infarct involving the whole rostro-caudal extent of the pontine tegmentum. This combination of electrophysiologic and pathologic findings may help answer questions regarding the exact generators of different MSEP potentials. In particular, it implies that medullary structures can generate the N18 potential.

Postpartum cerebral angiopathy. Is there a role for sympathomimetic drugs?

BACKGROUND: Postpartum cerebral angiopathy is associated with the use of of ergot alkaloids. The exact mechanism is unclear but may be related to their sympathomimetic properties, as evidenced in patients already on other ergot derivatives who deteriorated only after taking additional sympathomimetic drugs. We postulate that sympathomimetic agents, independent of ergot alkaloids, may produce the same complication. CASE DESCRIPTION: A postpartum patient, initially presenting with headaches, subsequently manifested rapid neurological deterioration after ingesting isometheptene, a sympathomimetic drug. She was not on any ergot derivative but presented similar clinical and radiological manifestations. She experienced increased headache severity, visual disturbance, and seizures associated with multiple segmental cerebral vasoconstriction on angiography and increased T2-weighted signal in the occipital areas on magnetic resonance imaging. CONCLUSIONS: This case is additional evidence that sympathomimetic actions of some drugs, such as ergot derivatives and isometheptene, may lead to postpartum cerebral angiopathy. Documentation of medication used by postpartum women suffering similar complications is needed to verify these findings.

Reassessment of the clinical significance of periodic lateralized epileptiform discharges in pediatric patients.

A review of clinical data from 18 pediatric patients with periodic lateralized epileptiform discharges and bilateral independent periodic lateralized epileptiform discharges (PLEDs and BIPLEDs) showed 2 with chronic neurologic illness, 6 with a history of prior seizures, 14 with depressed sensorium at the time of EEG, 5 deaths, and 8 of 13 survivors with neurologic deficits. These findings are similar to the combined data from reports involving adult patients only. Separating pediatric patients with PLEDs from those with BIPLEDs shows some influence from patients with BIPLEDs. Overall, our data do not suggest significant clinical differences for PLEDs between children and adults.

Defining the role of structural lesions and metabolic abnormalities in periodic lateralized epileptiform discharges.

We reviewed the EEG, clinical manifestations, computed tomography (CT) and magnetic resonance imaging (MRI) scans of 39 patients with periodic lateralized epileptiform discharges (PLEDs) or bilateral periodic lateralized epileptiform discharges (BIPLEDs) to determine the role of structural lesions (SL) and metabolic abnormalities (MA) in their pathogenesis. Thirty-eight patients had CT and 7 had MRI scans. Thirty-eight had lesions on CT or MRI. All those with PLEDs consistently had lesions on the side of the discharges, and 5 of 6 with BIPLEDs had lesions on both hemispheres. A subgroup of 23 patients with metabolic determination within 24 h of EEG all showed mild to moderate MA. They all also had SL. These findings support a primary role for SL but cannot exclude an additional role for MA.

Carpal tunnel syndrome, subclinical median mononeuropathy, and peripheral polyneuropathy: common early complications of chronic peritoneal dialysis and hemodialysis.

Nerve conduction velocity studies were done in median, ulnar, and peroneal nerves, one time each in 46 patients who had been on chronic peritoneal dialysis or hemodialysis for varying lengths of time. Only six patients had normal findings; 37 had peripheral polyneuropathy (15 had isolated polyneuropathy; 22 had median nerve dysfunction in addition); 16 had subclinical median mononeuropathy (14 with polyneuropathy, two without); and nine had overt carpal tunnel syndrome (eight with polyneuropathy, one without). Abnormalities were present in seven of the 11 patients studied after one year of dialysis and in 19 of the 24 patients studied after two years of dialysis. Seventeen patients studied after five years of dialysis all had polyneuropathy. Nine patients studied after seven years of dialysis all had median nerve dysfunction. Abnormalities were as common with peritoneal dialysis as with hemodialysis. Nerve dysfunction was independent of the disease underlying renal failure, the side of the dialysis access shunt, and the presence or absence of osteodystrophy. Dialysis patients need frequent nerve conduction studies from the onset of dialysis to identify carpal tunnel syndrome early and to avoid irreversible nerve damage.

Neoplastic angioendotheliomatosis.

A 60-year-old white man presented with aphasia, seizures, paraparesis, and incontinence. His serologic and hematologic profiles were unremarkable. His cerebrospinal fluid showed pleocytosis, increased daily central nervous system IgG synthesis, increased myelin basic protein, and negative cytology and cultures. Cerebral computed tomography exhibited multiple areas of hypodensity but spinal computed tomography and myelography showed no abnormalities. Cranial and spinal magnetic resonance imaging revealed areas of increased signal on T2-weighted images. The use of gadolinium-pentetic acid on T1-weighted images delineated smaller areas of cortical enhancement with surrounding rim of decreased signal. Brain biopsy showed intravascular malignant cells positive for leukocyte common antigen and B-cell markers. The diagnosis was neoplastic angioendotheliomatosis (intravascular lymphomatosis). To our knowledge, this is the first report on the use of both cranial and spinal magnetic resonance imaging in this condition.

Neurologic involvement in toxemia of pregnancy: reversible MRI lesions.

Three women presenting with toxemia of pregnancy revealed reversible increased signal intensity on T2-weighted images by MRI. Overall, neuroradiologic techniques, with MRI the most sensitive, help elucidate the pathophysiology and facilitate the diagnosis in this condition.

Möbius syndrome and transposition of the great vessels.

A case of Möbius syndrome was associated with transposition of the aorta and pulmonary artery, as well as acheiria. This combination of anomalies supports the hypothesis that Möbius syndrome is caused by an intrapartum insult during the fourth to seventh week of gestation and is consistent with the vascular theory of embryopathogenesis.