[The Bridge between Pediatric and Adult Neurology].

Pediatric and adult departments are differentiated based on a cutoff age of approximately 15-17 years. In clinical neurology, there are certain disorders and related problems that overlap these age-determined boundaries. In this review, the following three themes are discussed. (1) Manual dexterity: Considering motor skills through the developmental stages of a child and manual impairment due to localized brain damage in adults, manual dexterity has been reviewed extensively from the perspective of cortical association areas. (2) Hepatolenticular degeneration: Wilson's disease (children) and Westphal-Strümpell pseudosclerosis (adults) are compared and assessed based on the age of onset to identify differences in clinical symptoms and pathological findings. (3) Hirayama disease: This disease has been identified as an adult neurological disorder. Since the onset of Hirayama disease occurs around puberty in children and adolescents, it provides a connecting link between pediatric and adult neurology.

[Somatotopic Representation of the Anterior Horn within Cervical Enlargement: Reappraisal of Known Doctrine Based on Clinicopathological Findings Seen in Hirayama Disease].

Clinical features (weakness and amyotrophy of intrinsic hand muscles and obliquely distributed amyotrophy of forearm muscles, figure 1), needle electromyographic findings (distribution of neurogenic activities, figure 2), and pathological findings (ischemic necroses of the anterior horns between C6 and T1, figure 3) of Hirayama disease suggest that understanding of somatotopic representation of the anterior horn innervating arm muscles in the cervical enlargement of spinal cord differs from the known doctrine. Anterior horn cells of the intrinsic hand muscles are located between C7 and T1, those of forearm muscles and triceps brachii muscle as elbow extensor are, contrary to the known doctrine, located in C5 and C6, and those of elbow flexors such as biceps brachii and brachioradialis are located in C4 and above (figure 5). Development of dexterity in human hand may reflect development of cervical enlargement in accord with larger areas representing the hand and fingers on cerebral motor cortex.

The handkerchief guide: a simple and practical method to improve ataxic gait in cerebellar subjects.

OBJECTIVE: Ataxic gait can be remarkably improved by a simple method called the "handkerchief guide" involving the patient and caregiver holding opposite ends of a handkerchief and walking together. Our objective was to assess the effect of the handkerchief guide on gait in patients with cerebellar ataxia. METHODS: Gait analysis was carried out on seven patients with degenerative cerebellar disease (DCD), seven patients with unilateral cerebellar vascular disease (CVD), and seven healthy control (HC) subjects. All subjects performed two walking tasks: free walking (FW) and handkerchief-guided walking (HGW) on a 10 m pathway. In the HGW condition, each subject walked with the caregiver while maintaining slight tension on the handkerchief. The HCs and patients with DCD held the handkerchief with their right hand, while the patients with unilateral limb ataxia due to CVD grasped it with their affected and unaffected hands in different trials. We measured 10 gait parameters. RESULTS: The HGW attenuated body-sway, lengthened step, and increased gait velocity in patients with cerebellar ataxia. In DCD, the HGW significantly improved seven parameters. In CVD, HGW with the affected hand improved five parameters, and HGW with the unaffected hand improved seven parameters. CONCLUSIONS: The HGW stabilized upright posture in patients with cerebellar ataxia during level-ground walking, probably by enabling subconscious postural adjustments to minimize changes in the arm and hand position relative to trunk, and in arm configuration. This led to improvement of gait performance. The handkerchief guide may be useful for walk training in patients with cerebellar ataxia.

[Thumb/big-toe localizing test: examination for deficit of proprioception through the posterior column-medial lemniscal system].

"Thumb localizing test" (TLT) and "big-toe localizing test" (BLT) are bedside examinations to detect abnormalities in proprioceptive afferent pathways from the limbs. In TLT, the patient is asked to close the eyes, one upper limb of the patient is placed in a fixed position by the examiner, and the patient is asked to localize the thumb of the fixed upper limb with the thumb and index finger of the other upper limb. In BLT, the patient is asked to close the eyes, a lower limb is passively immobilized by the examiner, and the patient is asked to locate the big toe with either index finger. Normal subjects can perform these tests quickly and accurately by the shortest spatial route, but some patients with neurological diseases show a deficit despite having normal sense of joint movement and position (JMP) for any of the joints of the fixed limb (so-called deep sensation). TLT/BLT deficits in such patients are caused by insufficient transmission or impaired integration of a proprioceptive sensation of the fixed limb that differs from discriminative sensation such as JMP and tactile cutaneous localization. TLT and BLT are more sensitive than the tests for JMP. BLT, in conjunction with TLT, is a more sophisticated bedside examination for determining the site of the lesion of the peripheral and central nervous systems.

[Juvenile muscular atrophy of unilateral upper extremity (Hirayama disease)--half-century progress and establishment since its discovery].

This disease occurs in adolescence, predominatly in male. The main clinical features include predominantly unilateral muscular weakness and wasting of the hand and forearm (the brachioradialis is spared: oblique amyotrophy). The clinical course is incidious onset and slowly progressive, followed by a spontaneous arrest within several years. Twelve patients with this disease were first reported by Hirayama and his associates in 1959, who clinically distinguished this disorder from previously known degenerative and progressive motor neuron diseases. The clinical features had been further clarified by the report on 20 patients in 1963, and completed in the report on 38 patients in 1972. A quarter of a century had passed without pathological confirmation, primarily due to the benign course of the disease. The first autopsy case was obtained in 1982. The neuropathological findings were reported by Hirayama and his associates in 1985 in Japanese, then in 1987 in English. The spinal cord showed anteroposterior flattening and ischemic necrotic changes of the anterior horns of the cervical cord at C5-T1, mostly severe at C7 and C8, predominantly on the left (the patient had bilateral muscular atrophy, predominantly on the left). These findings suggested a circulatory insufficiency of the lower cerivical cord, but the intra- and extra-medullary vessels were normal. The pathologic evidence prompted neuroradiologic (CT, MRI) studies in the late 1980s. Our studies of 73 patients revealed that dynamic compression of the lower cervical cord due to forward displacement of the cervical dural sac (especially posterior segment) and spinal cord on neck flexion was confined to an early and progressive stage of the disease. An absence of forward displacement in a later and non-progressive stage of the disease suggested that the dynamic compression had pathogenic significance. The pathologic findings and results of radiological studies suggest that sustained or repeated neck flexion might cause an anterior shift of the cervical dural sac, then the compressed cervical cord at the segments induce an increased intramedullary pressure, resulting in microcirculatory disturbance in the anterior horn, the most vulnerable structure to ischemia in the spinal cord. Based on this hypothesis, we tried cervical collar therapy for patients when they may have sustained or repeated neck flexion, and reported these data in 1991, 1992 and 2001. No one showed further progression of signs and symptoms. This favorable effect supports our pathogenic hypothesis described above. The author proposes that the etiology of this disease is disproportionate growth between the vertebral column and the contents of the spinal canal especially the dural sac during the juvenile growth. The nationwide epidemiological study in Japan was carried out from 1996 to 1998, identified 333 cases of the disease. There were fewer case reports from other countries than from Japan. As the number of patients is exceedingly large in Japan, there might be an ethnic factor in this disorder.

Nationwide survey of juvenile muscular atrophy of distal upper extremity (Hirayama disease) in Japan.

Juvenile muscular atrophy of the distal upper extremity (JMADUE, Hirayama disease) was first reported in 1959 as 'juvenile muscular atrophy of unilateral upper extremity'. Since then, similar patients in their teens or 20s have been described, under a variety of names, not only in Japan, but also in other Asian countries, as well as Europe and North America. Biomechanical abnormalities associated with JMADUE have recently been reported through various imaging examinations, proposing its disease mechanism. Since JMADUE differs from motor neuron disease, or spinal muscular atrophy, this disease entity should be more widely recognized, and early detection and effective treatments should be considered. We report an epidemiological study in Japan. Two nationwide questionnaire-based surveys, conducted in Japan from 1996 to 1998, identified 333 cases. The numbers of patients per year, distribution of ages at onset, mode of onset, time lapse between onset and quiescence, neurological signs and symptoms, imaging findings, and the effects of conservative treatments were analyzed. The peak age was 15 to 17 years, with a marked male preponderance, usually a slow onset and progression, and quiescence six or fewer years after onset. There was a predominantly unilateral hand and forearm involvement with 'cold paresis'. The imaging findings are described.

[Symptomatological and electrophysiological study on cold paresis in juvenile muscular atrophy of distal upper extremity (Hirayama's disease)].

Patients with juvenile muscular atrophy of distal upper extremity (Hirayama's disease) often show marked weakness of the fingers occurring with exposure to cold. We term this phenomenon cold paresis. We conducted an original test to induce cold paresis (Cold Paresis Inducement Test) in 11 patients of this disease and 10 normal controls. Cold paresis was induced in 9 of 11 patients, but was not induced in the 2 patients who had the disease longer than 20 years and in all normal controls. We examined the electromyogram of abductor digiti minimi during 5 Hz and 20 Hz rate of ulnar nerve stimulation at cooling. The patients in whom cold paresis was induced exhibited a waning of amplitude of compound muscle action potential (M wave) during 20 Hz stimulation. This waning was aggravated by intravenous administration of anticholinesterase (edrohponium). We found a remarkable conduction delay of M waveform at the waning by means of waveform analysis. These results suggest that cold paresis may be caused by a conduction block of the muscle fiber membrane in re-innervating muscles after active denervation.