Mitsuo Takahashi

Analysis of somatosensory evoked potentials to lateral popliteal nerve stimulation in man

Abstract Somatosensory evoked potentials (SEPs) to the lateral popliteal nerve were studied in 41 normal subjects. Analysis of the SEPs was carried out by observing amplitude distribution over the scalp, recovery function and alteration during sleep. 1. 1. The wave form of the SEPs was fairly consistent from subject to subject. The SEP had an initial positive peak (P1) and a negative peak (N1) at latencies of approximately 34 and 45 msec, respectively, and five alternative positive and negative peaks (P2, N2, P3, N3 and P4). For the sake of description, the response was divided into four components (components 1, 2, 3, and 4), each having the peak at P1, P2, P3 and P4, respectively. 2. 2. Scalp distribution of component 1 was restricted in the parietal area just posterior to the vertex, whereas that of component 2 was shifted more anteriorly. Component 3 had the widest distribution among all. Component 4 showed the next widest symmetrical distribution with the maximum at the vertex. 3. 3. After maximal excitation, components 1 and 2 recovered the control responsiveness at approximately 200 msec and 600 msec, respectively. Components 3 and 4 had much slower recovery processes. These components were still depressed even at 800 msec. 4. 4. When sleep progressed from stage 1 to stage 2 and further stage 3, component 1 was decreased without changing its peak latency, and the peak latency of component 2 was prolonged with an increase in amplitude. 5. 5. By comparison with the results of previous studies in animal and man, it was inferred the component 1 would be the postsynaptic potential of the primary response mediated by the specific thalamo-cortical projection system and would correspond to the component 2 of the medial nerve SEP as established by Allison (1962) and Goff et al. (1962). Component 2 may correspond to the association response of Amassian (1954). Component 3 may probably be related to the non-specific diffuse projection system. Component 4 may represent the positive phase of the V-potential.

Dopamine metabolism in the central nervous system after discontinuation of l-dopa therapy in patients with Parkinson disease

The dopamine turnover rate in the central nervous system (CNS) of parkinsonian patients was studied by means of the intravenous probenecid test during drug holiday (DH) and alternate day L-dopa therapy (ADDT). After L-dopa therapy was stopped, the dopamine turnover rate decreased more rapidly in patients with the marked wearing-off phenomenon than that in patients without fluctuation of symptoms. The lumbar CSF concentrations of L-dopa and 3-O-methyldopa of patients with and without wearing-off phenomenon were similar during L-dopa therapy. DH improved the effect of L-dopa on parkinsonian symptoms; it did not affect, however, the metabolism of exogenous L-dopa. The dopamine turnover rate in the CNS before L-dopa therapy or on on-days did not differ between patients tolerating and those not tolerating ADDT. However, it was significantly lower on off-days in patients not tolerating ADDT than in those tolerating ADDT. The relationship between dopamine storage in the CNS and the response to L-dopa therapy is discussed.

Decreased activities in mitochondrial inner membrane electron transport system in muscle from patients with Kearns-Sayre syndrome.

The present study shows biochemical data on skeletal muscle from 5 patients with Kearns-Sayre syndrome (KSS). Enzyme activities per muscle wet weight in the electron transport system of inner mitochondrial membrane were not significantly different in KSS from those in normal subjects except one patient with long duration of symptoms. On the other hand, mitochondrial contents were increased and enzyme activities per mitochondrial protein in the electron transport system were markedly decreased in the muscle of all cases. These results suggest that the decreased enzyme activity of the mitochondrial electron transport system in each mitochondrion may result in a compensatory increase in mitochondrial contents in the muscle of KSS.

Mitochondrial Encephalomyopathy with Sleep Apnea

A rare case with mitochondrial encephalomyopathy, in association with cerebellar ataxia, peripheral neuropathy, mental retardation and alveolar hypoventilation syndrome with sleep apnea, as demonstrated by polysomnography, was encountered. This combination has not been described previously. From a prognostic point of view, alveolar hypoventilation syndrome with sleep apnea is an important clinical feature is this disease entity. Neither ataxia nor the abnormality of pyruvate metabolism was alleviated after 6 months of therapy with coenzyme Q10.

The Guillain-Barré syndrome: clinical and electroneuromyographic studies

SummaryClinical and electrophysiological studies were carried out on 39 patients with the Guillain-Barré syndrome to evaluate which elements were of prognostic value during the acute phase. Residual clinical signs such as motor weakness and absent patellar tendon reflexes were found in 16 (52%) of those patients who had had a preceding illness. Persistence of deficit was significantly correlated to age at onset, the degree of quadriparesis and loss of deep sensation in the acute phase. Of the 10 patients who showed a reduction in motor nerve conduction velocity (MCV) in the early stage, 8 (80%) revealed significantly residual clinical symptoms at follow-up. There was a tendency for the incidence of residual signs to be more common in the patients with slowing of mixed nerve conduction velocity, and prolonged latency of H-wave and the residual latency. Nerve conduction studies, especially measurement of MCV, were of value as a reliable prognostic indicator in this syndrome.ZusammenfassungKlinisch-elektrophysiologische Untersuchungen wurden bei 39 Patienten mit Guillain-Barré Syndrom durchgeführt. Es ging um die Frage, welche Elemente in der akuten Phase eine prognostische Beurteilung zulassen. Bei 16 der Patienten, was 52% des Krankengutes entspricht, wurden residuelle Symptome wie motorische Schwäche, fehlende Patellarsehnenreflexe und so weiter nachgewiesen. Das Zurückbleiben von residuellen Symptomen korrelierte mit dem Alter bei Krankheitsbeginn, das Ausmaß der Tetraparese und das Ausmaß der Sensibilitätsstörungen in der akuten Phase. Acht der zehn Patienten, die eine Verminderung der motorischen Nervenleitgeschwindigkeit in einer frühen Krankheitsphase aufwiesen, zeigten später nennenswerte Restsymptome. Tendenzmäßig schienen Restsymptome häufiger bei jenen Patienten zu sein, welche eine Verlangsamung der Leitgeschwindigkeit gemischter Nerven und eine verlängerte Latenz der H-Welle sowie der Residuallatenz aufwiesen. Elektroneurographische Untersuchungen, im besonderen die Bestimmung der motorischen Leitgeschwindigkeit, erlauben zuverlässige Rückschlüsse auf die Prognose dieses Krankheitsbildes.

Trophic effect of iron-bound transferrin on acetylcholine receptors in rat skeletal muscle in vivo ☆

Trophic effect of iron-bound transferrin (FeTf) on the total content of acetylcholine receptors (AChRs) and the specific activity of AChRs in innervated and denervated skeletal muscle was investigated in vivo. The right ischiadic nerves of 15 rats weighing 160 g were transected. FeTf (1.2 mg/ml) was injected daily into bilateral crural muscles of rats for the following 11 days. Control groups received injections of saline or no treatment. FeTf significantly increased the total content of AChRs and the specific activity of AChRs in innervated and denervated muscle compared with control groups (P less than 0.001). This result shows that intramuscular injections of FeTf may be useful for the treatment of disorders of neuromuscular transmission.

Effect of Protamine on Ion Selectivity of Superficial and Juxtamedullary Proximal Straight Tubules

Protamine is known to inhibit cation selectivity of the paracellular shunt pathway in several leaky nephron segments. Ion permeability of the superficial (SF) proximal straight tubules (PST) is selective to Cl^–, whereas that of the juxtamedullary (JM) PST is selective to Na⁺. Protamine was used to estimate the contribution of the paracellular shunt pathway to ion selectivity in these segments. PSTs were isolated from the kidneys of Japanese white rabbit and microperfused in vitro. The ratio of Na⁺ to Cl^– permeability (P_Na/P_Cl) was estimated from the diffusion potential (dV_T) generated by NaCl gradients. When 300 µg/ml protamine was added to the lumen, P_Na/P_Cl was decreased from 0.33 to 0.26 in SF-PST and from 1.80 to 1.29 in JM-PST, respectively, as the results of inhibition of cation selectivity. Addition of 30 U/ml heparin to the lumen, which neutralizes protamine, returned the ratios toward the control levels. Protamine exhibited similar effect on P_Na/P_Cl in the presence or the absence of ouabain in the bath, indicating that the observed voltage deflections were independent of the transcellular active transport process. Although P_Na/P_Cl was different between SF- and JM-PST, protamine inhibits Na⁺ permeability in both segments. Preferential Cl^– permeability in the SF-PST may be intrinsic to the paracellular route of this segment. The mechanism of this anion selectivity remains to be established.

Resistance of the peripheral nerve to ischemia in diabetic patients--an electrophysiological study.

We studied the effect of ischemia on the excitability of the sensory fibers of the median nerve in 43 patients with non-insulin-dependent diabetes mellitus (NIDDM) by a double stimulation method. Ischemia caused significantly less reduction of nerve excitability in patients with poor glycemic control and in patients diseased for 5 years or longer than in the normal control group. Hyperexcitability after ischemia was markedly greater than normal among short-term, poorly controlled diabetics, and markedly less pronounced among long-term, poorly controlled diabetics. In many diabetic patients with normal conduction velocity or without sensory disturbance, post-ischemic hyperexcitability was remarkable. A study of nerve excitability may be useful as one means of detecting early-stage disturbance of the diabetic peripheral nerve.

Focal luxury perfusion with an early-filling vein in relation to neurological symptoms evoked by heat

SummaryA 50-year-old man with a 1-year history of transient attacks of left total hemiparesis was admitted to hospital with a complaint of increasing frequency of attacks. Minimal or moderate left hemiparesis was elicited by elevation of environmental temperature when taking a hot bath or a hot shower. Right carotid angiography revealed an early-filling vein near the right central sulcus. An increase of focal luxury perfusion by elevation of body temperature seemed to cause relative ischaemia in this paracentral gyrus.

Ethambutol Neuropathy: Clinical and Electroneuromyographic Studies

Abstract: Clinical features including changes in the peripheral nerve conduction were analyzed in 10 cases with ethambutol neuropathy. There were abnormalities in the visual field in seven and optic atrophy in five of 10 cases. Seven of 10 cases complained of numbness in the lower limbs. The age of onset and dose of ethambutol the patients continue to take after the occurrence of visual impairment were found to be important in determining the severity of neurological symptoms. A functional disturbance was more conspicuous in ethambutol neuropathy, particularly in the sensory system than in the motor system so far as the peripheral nerve conduction was serially examined. Some cases still had serious optic disturbances even about seven years after the onset of the disease and the presence of irreversible lesions was suspected.