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Biomedical subjects

O N Markand

Publications and source records attributed to O N Markand.

13 recordsLinked to original sources
PubMed1992

Genetic and radiation hybrid mapping of the hyperekplexia region on chromosome 5q.

Hyperekplexia, or startle disease (STHE), is an autosomal dominant neurologic disorder characterized by muscular rigidity of central nervous system origin, particularly in the neonatal period, and by an exaggerated startle response to sudden, unexpected acoustic or tactile stimuli. STHE responds dramatically to the benzodiazepine drug clonazepam, which acts at gamma-aminobutyric acid type A (GABA-A) receptors. The STHE locus (STHE) was recently assigned to chromosome 5q, on the basis of tight linkage to the colony-stimulating factor 1-receptor (CSF1-R) locus in a single large family. We performed linkage analysis in the original and three additional STHE pedigrees with eight chromosome 5q microsatellite markers and placed several of the most closely linked markers on an existing radiation hybrid (RH) map of the region. The results provide strong evidence for genetic locus homogeneity and assign STHE to a 5.9-cM interval defined by CSF1-R and D5S379, which are separated by an RH map distance of 74 centirays (roughly 2.2-3.7 Mb). Two polymorphic markers (D5S119 and D5S209) lie within this region, but they could not be ordered with respect to STHE. RH mapping eliminated the candidate genes GABRA1 and GABRG2, which encode GABA-A receptor components, by showing that they are telomeric to the target region.

Base Sequence↗
PubMed1992

Single photon imaging computed tomography (SPECT) for localization of epileptogenic focus in patients with intractable complex partial seizures.

Interictal and ictal HIPDM-SPECT brain scans were obtained in 38 patients who eventually underwent temporal lobectomy for treatment of medically intractable complex partial seizures (CPS). Interictal studies revealed decreased regional cerebral perfusion (rCP) in the temporal lobe corresponding to the eventual site of surgery in 76% of the patients. Similarly, ictal studies demonstrated increased rCP in 91% of the patients. Of the 33 patients who had both interictal and ictal SPECT studies, 23 (70%) showed increased rCP in the ictal state and decreased rCP in the interictal state in the same temporal lobe which was subsequently removed. The SPECT scans were particularly helpful in providing confirmatory evidence for localization and in deciding to undertake temporal lobectomy in 16 patients whose EEG studies had provided less secure localization. Our experience suggests that interictal and ictal SPECT brain imaging can be easily obtained and provides reliable localizing information in the epileptic patients being considered for temporal lobectomy.

Adolescent↗
PubMed1979

Brainstem auditory evoked responses in leukodystrophies.

Brainstem auditory evoked responses (BAERs) were recorded in seven patients with Pelizaeus-Merzbacher leukodystrophy (PMD), two with adrenoleukodystrophy (ALD), and one with metachromatic leukodystrophy (MLD). BAERs were altered in all patients, and the alterations were severe in 9 of the 10 patients. A patient with ALD who as yet had no neurologic symptoms showed only minimal abnormality of the BAERs, consisting of prolongation of the latency of wave V. In the remaining nine patients, only wave I generated in the extramedullary portion of the eighth nerve was recorded with or without a wave II. Subsequent components (III through VII) were absent. No abnormality of BAERs was observed in the 10 known carriers of PMD. The combination of BAERs and EEG is helpful in differentiating leukodystrophy from progressive gray matter diseases.

Adult↗
PubMed1978

Complex partial status epilepticus (psychomotor status).

A 20-year-old mentally retarded woman, who had a history of intractable epileptic seizures since early childhood, had prolonged episodes of confusion, decreased responsiveness and automatic behavior lasting as long as 2 days. These are believed to represent epileptic status of the complex partial (psychomotor) type because the electroencephalogram (EEG) recorded during two such periods showed continuous high amplitude, semirhythmic, 4 to 6 cycles per second (cps), spike activity over both frontotemporal regions; several interictal tracings revealed a consistent spike focus in the right anterior temporal area. Diazepam given intravenously during one such episode terminated both the abnormal behavior and the ictal discharges in the EEG.

Adult↗
PubMed1977

Epileptic seizures and abnormal electroencephalographic findings in hydrocephalus and their relation to the shunting procedures.

A total of 92 patients with hydrocephalus were studied. The incidence of seizures was significantly greater in the "shunted" group (18.2% in the "non-shunted" and 65.4% in the "shunted" group). All of the shunted patients who had seizures developed them after the placement of the shunt. Left sided focal motor seizures were the commonest focal seizures in the patients with right sided shunts. There was a higher incidence of abnormal EEG tracings in the "shunt" group (47% of the "non-shunt" patients and 95% of the "shunt" group). All types of focal EEG abnormalities, but particularly the slow wave foci, were seen more frequently over the hemisphere which had the shunt, and in more than half these localized to the neighborhood of the shunt itself. It is suggested that the shunt, which may act as a foreign body, may be responsible, at least in part, for these findings.

Adolescent↗
PubMed1977

Slow spike-wave activity in EEG and associated clinical features: often called 'Lennox' or "Lennox-Gastaut' syndrome.

Clinical features were studied in 83 patients with slow spike-wave activity in the EEG. Epileptic seizures, usually intractable, occurred in 82 patients. The majority had the onset of seizures during the first 2 years of life. Minor motor seizures alone or in combination with other types of seizures occurred in 80 percent, and most had more than one type of seizure. The combination of tonic-clonic, minor motor, and absence seizures was the commonest, occurring in 37 percent. Sixty-six patients were definitely retarded and 49 showed definite motor impairment. Etiologic factors responsible for cerebral insult were identified in 53 patients. Serial EEG studies showed a close relationship between the EEG patterns of hypsarrhythmia, independent multifocal spike discharges, and slow spike-wave activity. The eponym "Lennox-Gastaut" syndrome is appropriate for a patient who has slow spike-wave activity in the EEG, exhibits mental retardation, and has intractable seizures of various types. However, the syndrome does not imply a pathologic entity because many diverse processes, both static and progressive, can produce this syndrome.

Adolescent↗
PubMed1976

Eectroencephalogram in "locked-in" syndrome.

Twenty-three EEG studies in eight patients with "locked-in" syndrome were reviewed. The EEG was either normal or minimally slow in all except one patient. All showed reactivity to various stimuli. Photic stimulation elicited a photic driving response at one time or another in all the seven patients where it was attempted. Althouth the basic activity may be similar, it is the preservation of alertness and the presence of reactivity of the EEG which distinguishes the "locked-in" patients from those comatose due to an extensive brain stem lesion. In an unresponsive patient, an EEG resembling that of the waking state, although highly suggestive of an intrinsic brain stem insult, may also occur at times in association with diffuse cortical damage, secondary to prolonged cardio-pulmonary arrest.

Akinetic Mutism↗
PubMed1976

Clinical and electroencephalographic correlation of independent multifocal spike discharges.

One hundred and eight patients with independent, multifocal, spike discharges in the EEG were studied. The abnormality occurred at all ages but was more frequent between 4 and 7 years. The basic EEG activity in wake tracing was invariably slow for the age of the patient. The majority of the patients with independent multifocal spike discharges had extensive bilateral cerebral lesions that occurred in the prenatal, perinatal, or postnatal periods. Clinical seizures were of different types, and patients had varying degrees of intellectural and neurologic deficits. A significant number had had previous tracings with either hypsarrhythmic or slow spike-wave patterns, suggesting a close relationship of these three EEG abnormalities.

Adolescent↗
PubMed1976

Sleep abnormalities in patients with brain stem lesions.

Seven patients with "locked-in" syndrome were studied by prolonged polygraphic recordings. Severe alterations in the sleep pattern were observed in five patients who had bilateral extensive pontine lesions resulting in tetraplegia, facial and pseudobulbar paralysis, and absence of conjugate horizontal gaze. Rapid eye movement (REM) sleep was entirely absent while non-rapid eye movement (NREM) sleep was absent, reduced, or altered. The remaining two patients, both of whom had relative sparing of horizontal gaze and apparently either no or minimal pontine tegmental involvement, showed both REM and NREM sleep with only a minimal alteration in the sleep pattern. The study suggests that, in human beings as in animals, pontine structures near the midline are essential for control of sleep states.

Akinetic Mutism↗
PubMed1975

The electroencephalogram in subacute sclerosing panencephalitis.

Electroencephalogram studies of 31 patients with proved subacute sclerosing panencephalitis (SSPE) revealed periodic high-amplitude complexes in all except one. The periodic complexes consisted of two to four high-amplitude delta waves, were usually bisynchronous and symmetrical, and repeated once in five to seven seconds. When both the clinical myoclonic jerks and the periodic EEG complexes were present, a one to one relationship existed between the two phenomena. Besides periodic complexes, several atypical EEG findings were also noted that included frontal rhythmic delta activity in intervals between periodic complexes, electrodecremental periods following EEG complexes, paroxysm of bisynchronous spike wave activity, random spikes over frontal regions, and focal abnormalities, such as spike and slow wave foci. In spite of variability of EEG findings, there is usually no difficulty in making the diagnosis of SSPE if both the EEG and clinical findings are considered.

Adolescent↗
PubMedDate not supplied

Effects of hypothermia on short latency somatosensory evoked potentials in humans.

Short latency somatosensory evoked potentials (SSEPs) elicited by median nerve stimulation were monitored in 14 adult patients undergoing cardiac surgery under cardiopulmonary bypass and induced hypothermia. SSEPs were recorded at 1-2 degrees C steps as the body temperature was lowered from 37 degrees C to 20 degrees C to determine temperature-dependent changes. Hypothermia produced increased latencies of the peaks of N10, P14 and N19 components, the prolongation was more severe for the later components so that N10-P14 and P14-N19 interpeak latencies were also prolonged. The temperature-latency relationship had a linear correlation. The magnitude of latency prolongation (msec) with 1 degree C decline in temperature was 0.61, 1.15, 1.56 for N10, P14 and N19 components, respectively, and 0.39 and 0.68 for interpeak latencies N10-P14 and P14-N19, respectively. The rise time and duration of the 3 SSEP components increased progressively with cooling. Cortically generated component, N19, was consistently recordable at a temperature above 26 degrees C, usually disappearing between 20 degrees C and 25 degrees C. On the other hand, more peripherally generated components, N10 and P14, were more resistant to the effect of hypothermia; P14 was always elicitable at 21 degrees C or above, whereas N10 persisted even below 20 degrees C. The amplitude of SSEP components had a poor correlation with temperature; there was a slight tendency for N10 and P14 to increase and for N19 to decrease with declining temperature. Because incidental hypothermia is common in comatose and anesthetized patients, temperature-related changes must be taken into consideration during SSEP monitoring under these circumstances.

Adult↗
PubMedDate not supplied

Temperature-dependent hysteresis in somatosensory and auditory evoked potentials.

Fourteen adult patients undergoing open heart surgery under induced hypothermia had median nerve, short-latency somatosensory evoked potentials (SSEPs) recorded during cooling (from 36 degrees C to 19 degrees C) and subsequent rewarming. Similar data on another group of patients who had brain-stem auditory evoked potentials (BAEPs) were also analyzed. Hypothermia produced increased latencies of the major SSEP and BAEP components and the latencies returned to normal with subsequent warming. The temperature-latency relationship during the cooling phase was significantly different from that during the warming phase. For SSEP components the temperature-latency relationship was linear during cooling and curvilinear during warming, whereas for BAEP it was curvilinear both during cooling and warming. Furthermore, the regression curves were different during the two phases of temperature manipulation, particularly for temperatures below 30 degrees C both for SSEP and BAEP components. At the onset of warming there was an initial exaggerated warming response on the evoked potential (EP) latencies and amplitude of the EP components. The temperature-latency regression curves were uniformly less steep during the warming phase compared to those during cooling. These findings suggest the existence of hysteresis in the relationship between temperature and EP latencies. The latencies at a given temperature below 30 degrees C depend on whether that temperature is reached during cooling or during warming.

Acoustic Stimulation↗