Brain SPECT imaging and treatment with IVIg in acute post-infectious cerebellar ataxia: case report.

A 19 year-old man presented with pharyngitis and cervical lymphadenopathy, followed by vomiting and acute cerebellar ataxia. Serologic studies were consistent with a recent Epstein-Barr virus infection. Although contrast-enhanced brain computed tomography and MRI scans were normal, brain perfusion single photon emission tomography (SPECT) examination using 99mTc-HMPAO, performed on the 15th day of illness, showed marked cerebellar hyperperfusion, suggesting a diagnosis of acute post-infectious cerebellitis. After treatment with intravenous human immunoglobulin (IVIg, 2 g kg-1 over three days), progressive neurologic improvement occurred over two weeks. A brain SPECT study repeated after two additional weeks demonstrated a normal perfusion pattern. We conclude that brain perfusion SPECT examination is useful in identifying post-infectious cerebellitis and in monitoring its clinical course. In addition, IVIg may be helpful in treating this condition.

Slow oscillations of cytochrome oxidase redox state and blood volume in unanesthetized cat and rabbit cortex. Interhemispheric synchrony.

The purpose of this study was to determine the frequency characteristics and the degree of interhemispheric synchrony of slow (< 0.5 Hz), spontaneous oscillations of the regional cortical cytochrome oxidase redox state (CYT) and blood volume (CBV) in unanesthetized animals. We implanted bilateral cortical windows and electrodes for polysomnography in 7 cats and 3 rabbits. The animals were atraumatically restrained during multiple 3-6 hour sessions for up to 8 weeks, and relative changes in the cortical CYT and CBV were monitored by dual wavelength reflectance spectrophotometry at 603 nm and 590 nm. Continuous oscillations of CYT and CBV, unrelated to pulse or respiration, were always observed in each animal. Frequency (FFT) analysis over time revealed a nonstationary distribution of frequencies below 0.4 Hz, with most of the spectral power being contained in the 0-0.25 Hz band during both waking and sleep. Although the time-frequency plots of the CYT and CBV signals were similar, an occasional dissociation between the CYT and CBV oscillations was found. Analysis of simultaneous bilateral cortical optical recordings revealed a significant and sustained interhemispheric cross-correlation over time between the CYT as well as the CBV oscillations during stable recordings as long as 60 min. We conclude that: 1) CYT and CBV levels normally oscillate at < 0.4 Hz in the unanesthetized cat and rabbit cortex; 2) these complex oscillations, whose frequencies are non-stationary over time, nevertheless show sustained interhemispheric synchrony between 50 mm2 homotopic cortical regions; and 3) these oscillations may in part represent fluctuations of the metabolic rate.

Interhemispheric synchrony of slow oscillations of cortical blood volume and cytochrome aa3 redox state in unanesthetized rabbits.

In order to study spontaneous, slow oscillations of regional oxidative metabolism and blood flow in the normal, unanesthetized cortex, adult rabbits were implanted with bilateral cortical windows and electrodes for polysomnography. Relative changes in the cortical intramitochondrial redox state of cytochrome aa3 (CYT) and blood volume (CBV) were monitored by dual-wavelength reflectance spectrophotometry. Continuous, non-stationary oscillations (< 0.5 Hz) of both CYT and CBV were observed during waking and non-REM sleep. Cross-correlation analysis revealed a predominant interhemispheric synchrony of these oscillations which were unrelated to the heart rate, breathing, or electrocorticogram pattern. These findings suggest a dynamic linkage of slowly varying metabolic and vascular processes between unanesthetized cortical regions of 50 mm2 surface area.

MRI in intraventricular neurocysticercosis: a case report.

A young Mexican female developed neurocysticercosis presenting as a lymphocytic meningoencephalitis with eosinophilia. Parasitic cysts in the fourth ventricle and pre-pontine cistern were well visualized by magnetic resonance imaging but not by computerized tomography. The meningoencephalitis recurred despite treatment with praziquantel and dexamethasone, and obstructive hydrocephalus eventually developed. The patient remains well one year after excision of the intraventricular cyst. This case emphasizes the distinct advantages of magnetic resonance imaging in the diagnosis of intraventricular neurocysticercosis, and the potential need for surgical rather than medical intervention in this condition.

Low-frequency oscillations of cortical oxidative metabolism in waking and sleep.

To study the changes in cortical oxidative metabolism and blood volume during behavioral state transitions, we employed reflectance spectrophotometry of the cortical cytochrome c oxidase (cyt aa3) redox state and blood volume in unanesthetized cats implanted with bilateral cortical windows and EEG electrodes. Continuous oscillations in the redox state and blood volume (approximately 9/min) were observed during waking and sleep. These primarily metabolic oscillations of relatively high amplitude were usually synchronous in homotopic cortical areas, and persisted during barbiturate-induced electrocortical silence. Their mean amplitude and frequency did not vary across different behavioral/EEG states, although the mean levels of cyt aa3 oxidation and blood volume during rapid eye movement (REM) sleep significantly exceeded those during waking and slow-wave sleep. These data suggest the existence of a spontaneously oscillating metabolic phenomenon in cortex that is not directly related to neuroelectric activity. A superimposed increase in cortical oxidative metabolism and blood volume occurs during REM sleep. Experimental data concerning cerebral metabolism and blood flow that are obtained by clinical methods that employ relatively long sample acquisition times should therefore be interpreted with caution.

Hypokalemic periodic paralysis with unusual responses to acetazolamide and sympathomimetics.

Five members in three generations of a family were affected by an illness that had many clinical features of the hypokalemic form of periodic paralysis (HPP). The serum potassium was either moderately reduced or normal during attacks, and there was no evidence of myotonia or cold-intolerance. All of the patients improved to a variable degree with oral potassium supplements, and 3 responded favorably to triamterene. The usually beneficial drug acetazolamide, however, invariably caused weakness in these patients, an effect previously described in only one other family with HPP. In addition, amphetamine-like sympathomimetic drugs effectively aborted or prevented paralysis in several members. Muscle biopsy in two patients revealed some unusual features, and electromyography showed myopathic potentials. There was no evidence of diabetes. The urine electrolyte concentrations during glucose tolerance tests, however, were different from those previously reported in HPP. This family may represent a variant form of HPP.

Focal MRI findings in early SSPE.

Many investigators have identified localized cortical involvement in subacute sclerosing panencephalitis (SSPE) by clinical and electrophysiologic criteria. Some investigators have reported such abnormalities in the posterior cerebrum early in the course of the disease, but without radiologic correlation. Recently, magnetic resonance imaging has been used to follow the progression of SSPE. The largest reported study of SSPE utilizing magnetic resonance imaging indicated that focal abnormalities were distinctly rare and actually mitigated against the diagnosis of SSPE. We report an SSPE patient with focal cerebral dysfunction and magnetic resonance imaging evidence of distinctly focal inflammatory disease early in the course of the illness.

A simplified method for monitoring the cytochrome aa3 redox state in bilateral cortical areas of unanesthetized cats.

We describe a versatile optical system that enables the simultaneous monitoring of the redox state of cytochrome c oxidase (cytochrome aa3) in two homologous cortical areas under chronically implanted windows in cats. A single light source, broad bandpass primary filters, light-conducting rods, and narrow-bandpass interference detecting filters are employed. We observed reproducible responses of the cytochrome redox state and blood volume to carotid occlusion and terminal anoxia during anesthesia, and to graded doses of pentobarbital in awake animals.

The mechanism of pneumocephalus formation in patients with CSF fistulas.

A novel but simple explanation of how pneumocephalus develops across CSF fistulas is presented and applied to an unusual case of pneumocephalus. Preexisting models of pneumocephalus formation are discussed and a substitute model is suggested.

The relationship between visual seizures and visual evoked potentials.

We have studied a patient (pt) in status epilepticus with visual seizures (szs) arising focally from the right occipital area and have recorded the visual evoked potential (VEP) to three different stimuli under three different conditions (during, between and with no szs). The pt experienced "sparkling" in the contralateral visual field as the sz and the intensity of the "sparkling" was directly related to the frequency of the ictal activity recorded on the EEG. During the szs the VEPs could still be recorded, but the amplitude of the P100 was higher on the contralateral side with pattern reversal (PR) stimuli, and with flashes (FL) the positive peak after the P100 was less evident on the ipsilateral side. Latencies to these latter two positivities were generally shorter than in normals, with much greater standard deviations ipsilaterally with FL and contralaterally with PR, especially during the actual szs. The relationship between VEP generation and visual sz phenomena is discussed.

Distribution of cimetidine in postmortem tissues.

The postabsorptive distribution of cimetidine is described. Assays by high pressure liquid chromatography (HPLC) of postmortem samples of cerebrospinal fluid, serum, and solid tissues were used to determine pharmacokinetic parameters as well as mean tissue: serum concentration (T:S) ratios in seven patients with renal and liver dysfunction. Correlations were calculated between the T:S ratio and the volume of distribution, and between the T:S concentration ratio and the time of sampling after death. The highest T:S ratios occurred in the eliminating organs, the liver and kidneys, and the lowest in fat. As the time of autopsy increased after death, the T:S ratios decreased.

Transient thalamic hypodensity in lupus erythematosus with generalized seizures.

Computerized tomography revealed extensive bilateral hypodensity of the thalamus after an episode of severe arterial hypertension and convulsions in a patient with systemic lupus erythematosus. Radiologic and neurologic abnormalities were substantially resolved 1 week later. The unusual radiologic findings are discussed in relation to possible unique characteristics of vascular permeability in the thalamus.

Phenytoin and folic acid interaction: a preliminary report.

The effect of folic acid (1 mg/day orally) on phenytoin steady-state pharmacokinetics was studied in four male folate-deficient epileptic patients who were treated with only one anticonvulsant. Each patient served as his own control before and after starting folic acid replacement therapy. The Michaelis-Menten parameters, Vmax and Km, were calculated for each patient, and compliance with the single anticonvulsant drug (phenytoin) regimen was documented. Blood and urine samples were collected just before (day 1) and after 180 or 300 days of vitamin administration. Total and free phenytoin were measured in plasma; and phenytoin, 5-(p-hydroxyphenyl)-5-phenylhydantoin (p-HPPH), 5-(3,4-dihydroxyphenyl)-5-phenylhydantoin (DHD) were measured in 24-h urine. After the addition of folic acid, total phenytoin plasma concentration decreased 7.5-47.6% in three of the four patients, and the extent of this change correlated with Km (r2 = 0.99). Ratios of urinary metabolites to parent drug increased in those patients showing a decrease in plasma phenytoin caused by folic acid supplementation. This indicated that a folic acid-associated increase in phenytoin oxidative metabolism had occurred.

Phenytoin and folic acid: individualized drug-drug interaction.

The effect of folic acid supplementation on the disposition of phenytoin and the resultant loss of seizure control in a male folate-deficient epileptic is reported. Due to the increase in tonic-clonic seizures after the initiation of folic acid (1 mg, orally) the sodium phenytoin dosage was increased by 130 mg until control was achieved. Because of these dosage changes, the Vmax and Km were calculated before and after initiation of the folic acid. The Vmax remained relatively the same, but the Km decreased after folate supplementation.

Epileptic aphasia. First onset of prolonged monosymptomatic status epilepticus in adults.

Epileptic aphasia in adults is a rarely described syndrome. Its occurrence in individuals without a clear-cut history of seizures raises diagnostic difficulties with important therapeutic implications. Two such cases are reported in which the diagnosis was confirmed by EEG with a dramatic therapeutic response to anticonvulsant medication. The EEG criteria leading to detection of the epileptic nature of the syndrome are detailed. Maintaining a high index of suspicion in cases with fluctuating symptoms remains crucial for early diagnosis and management, especially in terms of differentiating epileptic aphasia from transient ischemic phenomena.

Effects of ischemia on the removal of extracellular potassium in cat cortex during pentylenetetrazol seizures.

Changes in cortical extracellular potassium activity ([K+]0), NADH fluorescence, and oxygen consumption were studied in anesthetized cats during pentylenetetrazol seizures. The effects of partial ischemia induced by either hypotension or intermittent carotid artery occlusion on these parameters were investigated. Nonischemic seizures were characterized by gradual generalized decreases in cortical NADH fluorescence and increases in O2 consumption, along with rapid increases in [K+]0, which then usually fell slightly as the ictal discharge continued. Ischemic seizures, on the other hand, were accompanied by complex changes in NADH fluorescence, by smaller delayed maximal increases in O2 consumption that lasted beyond the end of ictal activity, and by more sustained increases in [K+]0. The decay of [K+]0 after the termination of seizures in both nonischemic and moderately ischemic animals was not a monoexponential function: plots of ln delta [K+]0 versus time showed an initial linear decline (of slope M1) that rather abruptly slowed (to slope M2) after 2 to 5 sec and then often increased to the original rate. Both M1 and M2 were proportionately decreased by ischemia. In addition, the rate of [K+]0 removal could be slowed by acute ischemia induced either during or after the end of ictal activity. The initial rate of postictal [K+]0 removal (M1) was found to be linearly and inversely related to the level of cortical NADH fluorescence at the time of seizure termination. The results of this study suggest that an O2-dependent transport mechanism plays a major role in the removal of [K+]0 during and following the termination of generalized pentylenetetrazol seizures in the cat.

[K+]o clearance in cortex: a new analytical model.

1. It has been suggested that passive diffusion is the principal mechanism of the clearance of locally elevated extracellular potassium, K+o, in the cerebral cortex. This concept was based on the assumption that elevated K+ could be modeled as a point source. In the present study, the functional role of passive diffusion was reevaluated in the anesthetized cat cortex following local electrical stimulation. 2. The initial spatial distribution of extracellular potassium activity, [K+]o, elevated by monopolar stimulation, could be modeled by a two-dimensional Gaussian function at and below the 500-micron cortical depth. Azimuthal symmetry around the stimulating electrode was assumed and cylindrical spatial coordinates were used. 3. The observed clearance of transiently elevated [K+]o as a function of space and time was much more rapid than that predicted by an analytical model consisting of the homogeneous diffusion equation whose initial condition was the Gaussian spatial distribution of [K+]o at the onset of the clearance process. 4. It is concluded that passive diffusion does not significantly contribute to the rapid clearance of locally elevated extracellular potassium in the cortex. Active uptake of potassium by cortical cells should be more seriously considered as being primarily responsible for the potassium clearance.