Magnetoencephalography in the detection of focal lesions in West syndrome.

BACKGROUND: According to the international classification of epilepsy syndromes, West syndrome (WS) is a form of generalized epilepsy. However, it is known that localized lesions can induce WS and that patients with WS often subsequently develop focal seizures. We evaluated such patients using magnetoencephalography (MEG). METHOD: Fourteen patients of 3 months to 6 years of age who had or who had previously had WS were examined. MEGs were recorded using a laying-type whole-cortex MEG system with a 160-channel first-order gradiometer. Twelve-channel electroencephalography (EEG) and one-channel electrocardiography (ECG) were simultaneously recorded. Equivalent current dipoles were estimated at the point of spikes on the EEG. RESULTS: Patients were classified by magnetic resonance imaging (MRI) findings into a focal lesion group (group F, n=7) and a non-focal lesion group (group N, n=7). The dipoles estimated from the MEG were classified into three groups: W, with the dipoles distributed over a wide brain area (n=7); WC, dipoles distributed over a wide area along with a dense dipole distribution in a specific cortical area (n=3); and C, closed dipole distribution in a unilateral cerebral focal area (n=4). Patients were also classified by the stage of the disease during which the MEG was recorded, and by the type of seizure they experienced. Those with hypsarrhythmia examined early in the disease all had pattern W regardless of their lesion group, whereas those examined later exhibited more diverse dipole patterns that corresponded to seizure type. CONCLUSIONS: Dipoles were distributed widely over bilateral cerebral cortex when patients had infantile spasms with hypsarrhythmia whether or not they had focal lesions. The dipole distribution pattern in MEG changed according to changes in seizure type.

Comparison of SSR and QSART in early diabetic neuropathy--the value of length-dependent pattern in QSART.

We evaluated postganglionic sympathetic function using the sympathetic skin response (SSR) and quantitative sudomotor axon reflex test (QSART) on the feet of 31 patients with early diabetic neuropathy and 20 age-matched normal controls. The amplitude of SSR and the sweat volume of QSART were significantly decreased in the diabetic patients. We evaluated the sensitivity of the tests in detecting autonomic failure. Out of 31 patients, 14 (45%) had abnormal SSR (14 absent; 17 present), while 16 of 31 patients (52%) had abnormal QSART (1 absent; 5 absolutely reduced and 10 showed a length-dependent pattern of reduction). More important than differences in sensitivity is the specificity of QSART, which specifically evaluates the postganglionic axon (instead of polysynaptic pathways in SSR) and provides quantitative data on the severity and pattern of autonomic deficit. In normal controls under 65 years of age, there was a significant correlation between the amplitude of SSR and the sweat volume of QSART. However, there was no significant relationship between these in diabetic patients. These results suggest that QSART can evaluate early diabetic neuropathy more precisely than SSR.

[A case of mononeuritis multiplex associated with type I (monoclonal) IgG kappa cryogloblinemia].

We here reported a fifty-three year-old woman with mononeuritis multiplex, associated with type I cryoglobulinema induced IgG kappa MGUS (monoclonal gammopathy of undetermined significance). She first experienced numbness in the extremities, that showed stepwise deterioration for several weeks. The nerve conduction study revealed axonal neuropathy, and laboratory examination detected type I cryoglobulinema. The sural nerve biopsy demonstrated with severe axonal degeneration with focal accentuation, lacking any inflammatory response. Single cryofiltration definitely stopped the progression of the symptoms. The prompt clinical response to the removal of cryoglobulin, without the administration of anti-inflammatory drugs, confirmed the direct etiological correlation between type-1 cryoglobulin and the neuropathy, and may favor ischemic, rather than inflammatory nature of this rare type of neuropathy.

Temporal fluctuations of voltage-gated proton currents in rat spinal microglia via pH-dependent and -independent mechanisms.

Voltage-gated proton (H(+)) channels are unique mechanisms to extrude a massive amount of H(+), and are proposed to regulate intracellular pH of microglia during respiratory bursts. Temporal variations of the H(+) current were studied in rat spinal microglia cultivated on the glial cell layer using the voltage-ramp protocol. Repetitive applications of the large and long-lasting depolarization decreased the amplitudes of the H(+) current transiently and reversibly. This decrease was accompanied by a shift of the reversal potential to a more positive direction, indicating that a drop in the transmembrane pH gradient (delta pH) by the H(+) efflux through the channel reduced the current. The decline of the H(+) current during depolarizations was also observed in a rat microglial cell line (GMI-R1). An increase in the extracellular buffer suppressed the reduction of the current, suggesting that H(+) secreted into the extracellular space contributed to the drop in delta pH. On the other hand, the amplitudes of the H(+) current often fluctuated greatly at intervals of 5-20 min without changes in delta pH. These results suggest that the H(+) current of microglia is tuned via both delta pH-dependent and -independent mechanisms, which may regulate both microglial behavior and the pH environments of the surrounding neural tissue.

Potentiation of a voltage-gated proton current in acidosis-induced swelling of rat microglia.

Microglia are equipped with a strong proton (H(+)) extrusion pathway, a voltage-gated H(+) channel, probably to compensate for the large amount of H(+) generated during phagocytosis; however, little is known about how this channel is regulated in pathological states. Because neural damage is often associated with intracellular and extracellular acidosis, we examined the regulatory mechanisms of the H(+) current of rat spinal microglia in acidic environments. More than 90% of round/amoeboid microglia expressed the H(+) current, which was characterized by slow activation kinetics, dependencies on both intracellular and extracellular pH, and blockage by Zn(2+). Extracellular lactoacidosis, pH 6.8, induced intracellular acidification and cell swelling. Cell swelling was also induced by intracellular dialysis with acidic pipette solutions, pH 5.5-6.8, at normal extracellular pH 7.3 in the presence of Na(+). The H(+) currents were increased in association with cell swelling as shown by shifts of the half-activation voltage to more negative potentials and by acceleration of the activation kinetics. The acidosis-induced cell swelling and the accompanying potentiation of the H(+) current required nonhydrolytic actions of intracellular ATP and were inhibited by agents affecting actin filaments (phalloidin and cytochalasin D). The H(+) current was also potentiated by swelling caused by hypotonic stress. These findings suggest that the H(+) channel of microglia can be potentiated via cell swelling induced by intracellular acidification. This potentiation might operate as a negative feedback mechanism to protect microglia from cytotoxic acidification and hence acidosis-induced swelling in pathological states of the CNS.

HTLV-I-associated myelopathy: acute progression and atypical MR findings.

We describe serial MR imaging findings in a patient with HTLV-I-associated myelopathy. The patient had acute progression of neurologic symptoms and exhibited swelling of the entire length of the spinal cord with increased T2 signal and contrast enhancement on MR imaging. The spinal cord became atrophic a few years later.

Determining the appropriate stimulus intensity for studying the dipole moment in somatosensory evoked fields: a preliminary study.

OBJECTIVE: To establish a simple method of determining the appropriate stimulus intensity for studying the dipole moment in somatosensory evoked fields. METHODS: In 17 patients (20 hemispheres), the authors studied the relationship between the dipole moment and stimulus intensity, which was quantified using the threshold of thenar muscle twitch (TMT). The dipole moment was measured at 1.0, 1.5 and 2.0 TMT. Two measurements were obtained at 1.5 TMT to determine the procedure's margin of error. RESULTS: There was no significant difference between the dipole moments measured at 1.5 and 2.0 TMT. CONCLUSIONS: Setting the stimulus intensity at 1.5 TMT or more ensures a consistent response.

Correlation of clinical improvement with pontine lesions in opsoclonus-myoclonus syndrome.

In a case of acute disseminated encephalomyelitis displaying opsoclonus-myoclonus syndrome, magnetic resonance images (MRI) disclosed pontine lesions involving part of the pontine paramedian reticular formation and the raphe nucleus. Shrinkage of the lesions correlated with the patient's clinical state. This observation supports the hypothesis that a pontine lesion can cause opsoclonus-myoclonus syndrome.

[A case report of central pontine and extrapontine myelinolysis which occurred during pregnancy and was accompanied by choreic movement].

A 25-year-old female in the 17th week of pregnancy was diagnosed by MRI as having central pontine and extrapontine myelinolysis. Serial observations with MR showed gradual disappearance of the lesions in the pons and striatum. Improvement of the symptoms took place shortly before disappearance of the lesions on MRI pictures. The initial symptoms were consciousness disturbance, cranial nerve palsy and tetraparesis. Before the latter disappeared seven months after occurrence of the disease, all other symptoms gradually improved. They were followed by delayed appearance of choreic movements, which was still remaining one year after discharge. It is rare for a pregnant woman to be attacked by central pontine myelinolysis. Moreover, very few symptoms caused by such extrapontine lesions have so far been reported. Also, a review of the relevant literature by the authors found no other case showing choreic movements. This report is of an extremely rare case of central pontine and extrapontine myelinolysis which occurred during pregnancy and is accompanied by choreic movements.