Tomoko Hashimoto

Cerebellar stimulation in acute cerebellar ataxia.

OBJECTIVES To report follow-up studies of cerebellar stimulation in patients with acute cerebellar ataxia (ACA). METHODS We studied two patients with ACA. One patient also had decreased deep sensations in the feet due to combined diseases such as diabetic polyneuropathy and lumbosacral radiculopathies. We applied the technique of electrical stimulation over the cerebellum which was reported previously (Ugawa et al., J Physiol 441 (1991a) 57). RESULTS Conditioning stimulation over the cerebellum did not reduce the size of motor-evoked potentials to test magnetic stimulation of the motor cortex at conditioning-test intervals of 5, 6, and 7 ms in the acute stage in both patients. However, normal suppression was recognized in the recovery stage in both patients. CONCLUSIONS This technique was useful for follow-up evaluation of cerebellar function in patients with ACA and was also useful for distinguishing cerebellar ataxia from sensory ataxia in a patient with combined diseases.

An adult form of Alexander disease: a novel mutation in glial fibrillary acidic protein

Glial fibrillary acidic protein (GFAP) mutation has been reported in Alexander disease. We report a patient with the adult form of Alexander disease who shows a novel mutation in GFAP. This case presented with progressive dysarthria, dysphagia and spastic gait on the right side. Brain and spinal cord MRI showed marked atrophy of the medulla oblongata and spinal cord. Abnormal high signal intensities in the ventral medulla oblongata were detected bilaterally. There were no white matter lesions or contrast enhancing lesions. Recently, there have been reports of patients with a juvenile form of Alexander disease presenting with atrophy or signal abnormalities of the medulla or spinal cord. Atrophy of the medulla and spinal cord have specifically been described as suggestive of Alexander disease [1]. Sequence analysis of the GFAP gene of this patient showed a heterozygous c.221T>C mutation, predicting a p.M74T amino acid change. In all patients suspected of Alexander disease on the basis of MRI findings, GFAP analysis is necessary to confirm the diagnosis.

Unilateral positive-negative myoclonus in creutzfeldt-jakob disease

We report a patient with Creutzfeldt–Jakob disease who presented asymmetric myoclonus. Positive–negative myoclonus was seen only in the right extremities in association with periodic synchronous discharges (PSDs) on the electroencephalogram, although pure positive myoclonus was rarely seen in the left extremities, independently in PSDs. The duration of the silent period recorded in the right‐hand muscle produced by transcranial magnetic stimulation was much longer than that in the left‐hand muscle or that in normal subjects. Brain MRI diffusion‐weighted images showed signal hyperintensities in the putamen and cerebral cortex, including the motor cortex, predominantly on the left side.

Negative myoclonus in Creutzfeldt-Jakob disease.

OBJECTIVE To describe electrophysiological findings in a patient with Creutzfeldt-Jakob disease (CJD) showing negative myoclonus. METHODS AND RESULTS We studied this CJD patient electrophysiologically, in comparison with two patients with cortical reflex positive myoclonus due to benign adult familial myoclonic epilepsy (BAFME). Spontaneous negative myoclonus was associated with periodic synchronous discharges (PSDs) on the electroencephalogram, but negative myoclonus could also be induced by electrical stimulation of the median nerve in the CJD patient. This patient showed giant somatosensory evoked potentials (SEPs) and enhanced C reflexes, and the duration of the induced EMG silences was found to be significantly correlated with the amplitude of cortical SEPs. The duration of silent periods (SPs) produced by magnetic stimulation of the motor cortex was extremely long. The study of recovery function of SEPs suggested that the excitability of the somatosensory cortex was decreased during a long post-stimulus period. These findings were clearly different from those of patients with BAFME. CONCLUSIONS This CJD patient had two types of negative myoclonus; one was associated with PSDs and the other was cortical reflex negative myoclonus. The long-lasting decrease in excitability of the sensorimotor cortices after stimulation could be related to the occurrence of both types of negative myoclonus.

Mechanism of voluntary and involuntary movements in humans.

Publisher Summary This chapter investigates the neurophysiological functions of primary negative motor area (area 44) in motor control, such as voluntary movements, studied by single-pulse transcranial magnetic stimulation (TMS) and subdural electrical stimulation. It also examines the relationship between cortical oscillatory activity and voluntary and involuntary hand movements in humans. To elucidate whether area 44 is essential for the organization of voluntary hand movements, the chapter examines the effects of single-pulse TMS of area 44 on voluntary hand movements and electromyographic (EMG) activity in hand muscles. The results show that magnetic and electrical stimulation of area 44 produced motor-evoked potentials (MEPs) from the hand muscles, but did not produce MEPs from the lower extremities. The chapter concludes that area 44 has direct fast-conducting corticospinal projections. Repetitive 50 Hz electrical stimulation of area 44 in the patients with intractable epilepsy induced disturbance of voluntary movements, tonic muscle contraction, and muscle weakness, which were similar to motor apraxia.

Chapter 20 High-frequency oscillations in the human motor system

Publisher Summary This chapter examines the possibility that the polyphasic C reflex expresses high-frequency oscillations (HFOs) in the human motor system. Activity of similar cortical interneurons in the motor area is associated with control of movement, but it has been difficult to record HFOs in the human motor area. The C reflex used in the present study is the EMG activity that occurred via the sensory cortex, motor cortex, spinal motoneurons, and peripheral nerve. It is a prerequisite that the motor cortex be activated for manifestation of HFOs in the C reflex. Polygraphic analysis showed oscillatory activity of about 300 Hz over the sensorimotor area coupled to EMG oscillations. Patients with cortical myoclonus have a pathological, synchronous discharge of large populations of cortical neurons and many motor units. The chapter proposes that hypersynchronization of neural networks because of pathological gap junctions may contribute to the production of seizure and myoclonus.

P30.25 Neurophysiological findings in variant form of HAM/TSP

Background: Quantification of attention may pose difficulties in clinical assessment of patients with severe brain lesions. The event-related P300 potential, evoked by stimuli demanding attention, offers the possibility of measuring attention in compliant subjects. Use of highly-trained stimuli such as the first name can also evoke a P300, thus enabling testing in non-compliant patients. Methods: We recorded the patient’s name for use as target stimulus (20% probability), and constructed a computer-generated, meaningless derivate containing the same physical characteristics for use as standard stimulus (80% probability). We examined 40 patients suffering from brain lesions of various etiology (traumatic brain injury, TBI, n = 24, cerebrovascular incidents, n = 8, cerebral hypoxia, n = 10). Recordings were obtained 1–5 times per patient, 75 sessions in all, during different phases of remission of apallic syndrome. P300 responses were classified as present, probable, or absent. P300 amplitudes and latencies were correlated with remission phase. Results: P300 was present in 24%, probable in 41%, and absent in 35% of recordings. In the total patient population, P300 classification correlated with remission stage (Spearman q 0.221, p < 0.05). In the TBI subgroup particularly (n = 49), P300 amplitude correlated with P300 classification (0.585, p < 0.001), and more importantly, with remission phase (0.483, p < 0.001). Discussion: The results document the feasibility of P300 testing for evaluation of attention in (post-) apallic patients. For the first time, we present a correlation of an objective parameter of attention with remission from apallic syndrome. However, the neurophysiological parameters accompany clinical signs but do not precede them, thus limiting their predictive value. Applying this modified P300 technique in non-compliant patients may allow objectification of reported or observed clinical changes in reaction or behaviour of severely disabled patients.

[Sensory ataxia in peripheral neuropathies--etiological and pathological analysis of four cases]

Among 85 neuropathy patients admitted and studied in the Department of Neurology, University of Occupational and Environmental Health, Japan, from 1979 to 1990, four patients suffering from sensory ataxia are reported with special reference to their etiological and pathological conditions. All of them were classified as having immune-mediated neuropathy. The first patient, a 56-year-old woman, was diagnosed as having chronic progressive ataxic sensory neuropathy. Her symptoms became progressively worse over a nine-year period after onset, but no evidence of cancer has been revealed. The positive rheumatoid factor was the only other feature noted. The second patient, a 63-year-old woman, after extensive laboratory studies, including the biopsy of the lymph node at the bifurcation of the bronchus in search of the cancer, was diagnosed as having subacute sensory neuropathy with small cell carcinoma of the lung. Chemotherapy was completed without subsequent obvious clinical benefits. The clinical diagnosis was confirmed on autopsy 29 months after the onset. The symptoms of the first patient were indistinguishable from those of the second patient, especially in the early clinical stage. In both patients, the proprioceptive sensations were severely affected and the disturbance of the proprioceptive sensations seemed to be almost parallel with the ataxia signs. The main site of the lesion seemed to be the neuron in the dorsal root ganglion in the first patient, as well as in the second patient who showed a marked loss of neurons in the dorsal root ganglion considered to be the primary lesion on autopsy.(ABSTRACT TRUNCATED AT 250 WORDS)

[A case of HTLV-I associated myelopathy (HAM) complicated by mononeuritis multiplex].

A 42-year-old woman with progressive myelopathy and mononeuritis multiplex is reported. The neurological examination on admission revealed hyperreflexia of the four extremities with pathological reflexes and moderate muscle weakness of the lower extremities with spasticity. Sensory disturbance was distributed on the areas of the bilateral lateral cutaneous femoral, the superficial peroneal and sural nerves. The antibody to HTLV-I in the serum and cerebrospinal fluid was more than 8192X and 512X, respectively. No sensory potential was recorded in the sensory conduction study of bilateral lateral femoral cutaneous nerves. Corticosteroid therapy caused a marked improvement of the sensory and urinary disturbances and had a slight effect on the spastic gait. Our nerve conduction study found small sensory potentials with normal conduction velocities in the bilateral lateral femoral cutaneous nerves. These results suggested the presence of an axonal degeneration in the peripheral nerves in this case. There have been no reports in the literature regarding a case of HAM with mononeuritis multiplex.