Search PubMed⌕ Search

Biomedical subjects

R Kaji

Publications and source records attributed to R Kaji.

At least 127 records · Page 7Linked to original sources
PubMed1993

Pathological findings at the site of conduction block in multifocal motor neuropathy.

We report on 2 patients with multifocal motor neuropathy with focal conduction block involving motor but not sensory fibers at the site of nerve swelling. A nerve biopsy specimen from adjacent to the enlargement in 1 patient showed a perivascular area containing scattered demyelinated axons surrounded by small onion bulbs. The observed pathological findings are consistent with the conduction block considered characteristic of this neuropathy, although the underlying immunological mechanisms for selectivity and persistence remain undetermined.

Action Potentials↗
PubMed1993

Lack of prolonged cerebral blood flow change after transcranial magnetic stimulation.

To study the physiological changes in the human brain induced by transcranial magnetic stimulation (TMS), we measured cerebral blood flow (CBF) before and after TMS in 3 healthy volunteers with positron emission tomography (PET). The intersecting point of the figure-of-eight coil was positioned at C3. TMS was delivered 20-32 times at maximum intensity. CBF measured at 50 sec after the termination of TMS showed no significant change in the cerebral cortex corresponding to C3 or any other area. This finding indicates that the hemodynamic change in the brain induced by TMS, if any, lasts only for a short period.

Adult↗
PubMed1993

Comparison of recording characteristics of monopolar and concentric needle electrodes.

Although both monopolar and concentric needle electrodes (MNE and CNE) are widely used in clinical EMG examinations, relatively little attention has been paid to the different recording characteristics of these electrodes. We compared motor unit potentials (MUPs) recorded with MNE and CNE and confirmed that larger MUP pick-up fields and amplitudes are recorded with MNE than with CNE but found no differences in duration or the number of phases. To determine the cause of these differences, we analyzed fibrillation potentials (FPs) recorded with MNE and CNE in patients with peripheral nerve injury. The FPs recorded had similar wave forms and amplitudes. The pick-up field for the FPs, however, was about 2 times larger for MNE than for CNE. We conclude that the differences of the recording characteristics of MNE and CNE for MUPs mainly are produced by their different pick-up fields.

Adult↗
PubMed1993

Vibration-evoked sensory nerve action potentials derived from Pacinian corpuscles.

To evaluate sensory response to natural stimuli, we developed a method to record sensory nerve action potentials evoked by high-frequency vibratory stimulation. Trains of 250 Hz sinusoidal indentations with a duration of 100 msec were applied to the finger tip at a rate of 3 Hz. The responses were obtained with surface electrodes placed over the median and ulnar nerves at the wrist. Averaged wave forms consisted of two components: an initial diphasic or triphasic potential and the following low amplitude trains of discharges phase-locked to vibratory stimuli. Anesthesia of the skin at the stimulation site or tourniquet-induced ischemia of the limb eventually diminished both components. Neither of them therefore represented artifacts from electrode movement or electromagnetic field intrinsic to the stimulator. Various kinds of mechanoreceptors may contribute to the first component. Pacinian corpuscles probably give rise to the second component as the only skin receptors that can respond to high-frequency vibratory stimuli of 250 Hz. This method helps examine neural coding of the receptor and the peripheral nerve fiber mediating vibration sense.

Action Potentials↗
PubMed1992

Multifocal demyelinating motor neuropathy: cranial nerve involvement and immunoglobulin therapy.

We report two patients with multifocal demyelinating motor neuropathy whose symptoms improved after immunoglobulin infusion. Clinical signs included atrophy of the tongue and limb muscles, closely resembling that of motor neuron disease. Nerve conduction studies revealed multiple sites of motor conduction block without sensory abnormalities, suggesting selective involvement of motor fibers. Careful documentation of conduction block is required to diagnose this entity, which may be treated with immunoglobulin therapy.

Action Potentials↗
PubMed1992

[Migrant sensory neuritis--electrophysiological and pathological study].

Migrant sensory neuritis, which was first proposed by Wartenberg, is very uncommon and only a few case reports have ever been published. We described one case of migrant sensory neuritis and discussed the pathogenesis of this disease. A 44-year-old man noticed numbness in the lateral aspect of the dorsum of the left foot in February 1985. Physically, there was hypoesthesia in the region of left sural nerve with positive Tinel's sign. During the next 4 years, pain, tingling sensation or hypoesthesia appeared in the regions of the right superficial radial nerve, right axillary nerve, left intercostal nerve, left lateral plantar nerve, digital nerve of the right second digit, left saphenous nerve, right superficial peroneal nerve, left superficial radial nerve, bilateral ulnar nerves and bilateral median antebrachial cutaneous nerves one after another in a migrating fashion. Tinel's sign was also positive at the right superficial radial nerve. In some occasions, decreased deep tendon reflexes were observed, but there had been no muscle weakness. Some nerves showed complete recovery, but others showed persistent involvement. Some nerves were affected repeatedly. Laboratory examination failed to clarify underlying disease except for mild liver dysfunction. Electrophysiological study showed reduced amplitude of the sensory nerve action potential (SNAP) of right sural nerve, left ulnar nerve, right superficial radial nerve and digital branch of right median nerve with preserved sensory nerve conduction velocity. SNAP of left sural nerve was absent. These findings mean the cause of the sensory disturbance is axonal degeneration rather than segmental demyelination. There were no abnormalities in motor nerve conduction study.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1992

[Multifocal axonal motor neuropathy associated with anti-ganglioside antibodies].

We report a patient with asymmetrical patchy weakness of the limbs, and with autoantibodies against gangliosides GM1, GD1b, asialo GM1. Although electrophysiological studies did not reveal conduction block, treatment with prednisolone resulted in clinical improvement. A 52-year-old man was admitted to Kyoto University Hospital, because of gait disturbance. Neurological examination revealed a patchy distribution of weakness in the limbs. Deep tendon reflex was normal at the right knee, and was depressed at the right biceps. Other deep tendon reflexes were absent. There was a slight decrease in vibratory sensation in the distal portions of the lower extremities. Routine laboratory studies, heavy metal screen, vitamin, cryoglobulin, coproporphyrin and delta-amino levulinic acid in urine, and the protein value of the cerebrospinal fluid were normal. Head and neck MRI, and myelography were normal. Immunofixation electrophoresis showed IgM lambda M-protein in serum. Thin-layer chromatography with immunostaining showed his serum IgM reacted with GM1, GD1b, and asialo GM1. ELISA (Enzyme Linked Immunosorbent Assay) demonstrated high titers of anti GM1, GD1b and low titer of anti asialo GM1. Motor conduction studies showed no demonstrable conduction block, normal conduction velocities and the low amplitudes of CMAP. Sensory conduction studies showed no abnormalities except for slightly decreased amplitude of SNAP in sural nerve. Electromyography showed active denervation in extensor digitorum communis muscle, tibialis anterior muscle and left biceps brachii muscle. Muscle biopsy specimen revealed large and small group atrophy and there was perivascular mononuclear infiltration at one point.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoantibodies↗
PubMed1992

[Treatment of Guillain-Barré syndrome with "axonal" involvement by plasma exchange].

A 19-year-old man with Guillain-Barré syndrome (GBS), who had been bedridden, dramatically improved after plasma exchange despite electrophysiological evidence of severe axonal damage. We commenced the therapy at 24 days after the onset of illness. Each trial of plasma exchange improved the strength clinically and rapidly increased the amplitude of the compound muscle action potential. Four months later, muscle strength recovered to normal except for mild weakness of the distal limb muscles. The time course of such a prompt recovery precludes axonal regeneration as its underlying mechanism in our patient. We postulate that some humoral factor might have reversibly depressed the axonal excitability, causing clinical symptoms which mimic axonal degeneration. Plasma exchange is a choice of treatment even for patients with GBS showing electrophysiological findings suggestive of axonal involvement.

Adult↗
PubMed1992

[An adult case of transverse myelitis with erythema infectiosum].

We reported an adult case of transverse myelitis with erythema infectiosum. A 33-year-old female was admitted to Kyoto University Hospital because of a weakness in the lower extremities and "cloth-wearing" sensation of the trunk and legs. One month before admission, she became febrile and developed a symmetrical erythema on the extremities. At the same time she noticed a slight weakness of the legs and numbness in her fingers and toes, which disappeared next few days. A week later, she again developed a fever, severe weakness of the legs and "cloth-wearing" sensation on the trunk, and erythema appeared on the cheek. Physical examination on admission revealed a weakness and hyperreflexia in the extremities, in particular, knee and ankle jerk, and hypesthesia of the trunk and legs below the level of Th6. Cerebrospinal fluid (CSF) examination revealed 181/mm3 cells (mononuclear cell dominant) and 30 mg/dl protein. Magnetic resonance imaging, CT and electrophysiological studies indicated no abnormalities. IgM antibody against human parvovirus (B19) was detected in the serum and CSF. She was diagnosed as transverse myelitis with parvovirus infection and was medicated with prednisolone 40-60 mg/day, and improved gradually with the residua of a mild weakness of the legs and hypesthesia on the trunk between the level of Th6 and Th10.

Adult↗
PubMed1992

[Botulinum toxin trial for spasticity].

We treated three patients with spastic paraparesis with botulinum toxin (BTX). Two of them had scissors gait reflecting the hypertonus of adductors. In both, an injection of BTX to the responsible muscles improved gait, albeit transiently. The effect was shortlived, probably because increased tonus in non-injected portions compensated for the weakness of injected portions. In the third patient with no abnormality in tonus of the adductors, BTX injection in quadriceps caused a weakness with exacerbation of gait disturbance. We concluded that, in selected cases, BTX therapy is useful for spastic paraparesis to alleviate hypertonicity of the adductors.

Adult↗
PubMed1991

[On the mechanisms and diagnosis of conduction disturbances due to demyelination with special reference to multifocal demyelinating neuropathy (Lewis-Sumner)].

Multifocal demyelinating neuropathy with persistent conduction block can mimic motor neuron disease, but is potentially reversible. Its diagnosis rests upon electrophysiological demonstration of focal conduction block at multiple sites. Conduction block is the most important mechanism causing clinical symptoms in peripheral nerve demyelination. On the other hand, conduction slowing is not always associated with clinical symptoms. In 2 out of 9 patients with multifocal demyelinating motor neuropathy, MRI showed focal swelling of the nerve at the site of conduction block. Both of them had elevated titers of anti-GM1 antibodies. In one, we biopsied a portion of the medial pectoral nerve, which was adjacent to the focal swelling, at surgical exploration. Pathological findings included very thin myelin associated with large diameter fibers and small onion bulb formation, suggesting that remyelinative process is abortive in this disease leading to persistent conduction block. Anti-GM1 antibodies bound to the denuded axoplasmic membrane may interfere with the process by masking the cell surface markers. The reason why the sensory fibers are spared is unclear, but it may be possible that GM1 in sensory axons have less affinity to the antibody than that in motor fibers.

Adolescent↗
PubMed1991

[Treatment of focal dystonia with botulinum toxin].

We have studied the effect of botulinum toxin in patients with focal dystonia, not responding sufficiently to medical therapy. Injection of 5-100 units to the muscles, selected by EMG and clinical examination, invariably resulted in reduction of muscle tonus, although to a different degree depending on the dosage. The outcome after the first trial was best when dealing with small muscles in patients with blephalospasm or Meige's syndrome. In contrast, several attempts were required for the treatment of a large muscle as in torticollis, or multiple muscles as in writers' cramps. The effect lasted 1-3 months. With precise selection of the affected muscles and careful regulation of necessary dosages, this type of therapy may contribute to the treatment of focal dystonia.

Adult↗
PubMed1990

Effect of digitalis on clinical symptoms and conduction variables in patients with multiple sclerosis.

Digitalis has been shown to reverse conduction block in demyelinated nerve fibers in experimental animals. In the search for a symptomatic treatment of multiple sclerosis, digoxin (0.02 mg per kilogram of body weight) was given intravenously to 7 patients with probable or clinically definite multiple sclerosis. All of these patients had temperature-dependent symptoms. In 3 patients, improvement of clinical deficits was observed concurrent with significant changes in evoked potential findings. Digitalis derivatives may be useful in ameliorating symptoms in selected patients with multiple sclerosis.

Adult↗
PubMed1990

Vector short-latency somatosensory-evoked potentials after median nerve stimulation.

A new method has been developed for recording short-latency somatosensory-evoked potentials after median nerve stimulation. Negative electrical forces recorded with three orthodiagonal bipolar electrodes in the neck had a direction opposite to that of impulse conduction in the proximal peripheral and cervical somatosensory pathway. Sequential tracings of vectors opposite the electrical forces were made in three-dimensional display, thus reproducing the actual time sequence of electrical events in those structures. Fixed generators such as the subcortical nuclei were also analyzed with this technique, and multiple generators of N13 potential (N13a and N13b) were visualized. This technique may be useful in the functional evaluation of the somatosensory pathway in the cervical cord.

Adult↗
PubMed1990

[Multifocal demyelinating polyneuropathy with persistent conduction block (Lewis-Sumner syndrome)].

Multifocal demyelinating neuropathy with persistent conduction block (Lewis-Sumner syndrome) is a variant of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), which often clinically simulates a motor neuron disease (MND). We report here three patients initially suspected to have MND, who later were diagnosed as a Lewis-Sumner syndrome. One of them showed a remarkable clinical improvement after immunoglobulin therapy. The definitive diagnosis of this syndrome rests upon nerve conduction studies, uncovering multiple sites of persistent conduction block. Technically, it is important to exclude insufficient stimulus which may lead to an erroneous impression of conduction block. Magnetic stimulation, as compared to electric current, elicited larger responses possibly because of deeper current penetration. We found this mode of stimulation useful especially in testing focal demyelination requiring full activation of a diseased nerve at a most proximal segment.

Adult↗