Degenerative changes at the neuromuscular junctions of red, white, and intermediate muscle fibers. Part 2. Responses to long stump nerve section and colchicine treatment

The ultrastructure at the neuromuscular junction (NMJ) of red, white, and intermediate skeletal muscle fibers undergoes specific changes following either unilateral severance of the phrenic nerve or unilateral topical treatment of the phrenic nerve with colchicine. Both procedures were performed in the cervical region and produce similar rates of muscle fiber degeneration. The severity of degeneration appears to be related to muscle fiber type with white fibers being most severely affected and red fibers least affected. Degeneration rates of the axon terminal also correlate with fiber type in the orderwhite, intermediate, red. However, the rates of degeneration of the specific axon terminals are more rapid with surgical severance than with colchicine treatment. Statistical analysis of morphometric data indicates that hemidiaphragms denervated surgically exhibited significant axon terminal degeneration before significant muscle degeneration. Conversely, diaphragmatic muscle fibers of colchicine-treated phrenic nerves exhibit significant degeneration before loss of the axon terminal. Despite reversal of the temporal sequences for loss of axonal and muscular components between the two preparations, degenerative characteristics of muscle fiber structure are similar. This suggests that the presence of fiber-specific neurotrophic substances transmitted from the neuronal cell body to the axon terminal and released at the NMJ may be an important factor in the maintenance of normal muscle fiber morphology.     

A patient of Charcot-Marie-tooth disease with rigid spine and respiratory failure]

This report describes a case of a 17-year-old girl with Charcot-Marie-Tooth disease (CMT) representing rigid spine and respiratory failure. At age 11, she tended to walk on her toes and had difficulty in getting up from the floor without support. She became aware of flexion limitation of the neck at the age of 12. At 15 years of age, She began to have dyspnea on effort. When she was 17 years old, neurological examination revealed mild weakness of the upper extremities and severe weakness of the distal lower extremities, generalized wasting and areflexia. Superficial sensation was mildly impaired distally, and vibration sensation was severely impaired in the lower extremities. Motor and sensory nerve conduction velocities were mildly reduced, and compound muscle action potential of the tibial and peroneal nerves and sensory nerve action potential on ulnar and sural nerves were absent. Electromyography showed neurogenic changes with denervation potentials. Sural nerve biopsy revealed severe loss of myelinated fibers without any onion-bulb formation. As for family history, her elder sister showed moderate loss of vibration sensation in the lower extremities. On the basis of these findings, she was diagnosed as having CMT type 2, though a mode of inheritance was uncertain. She also had peculiar findings of flexion limitation of the spine (rigid spine), contracture of the hip joint, and fatty degeneration of paraspinal muscles on CT. Percent vital capacity (VC) was 22.5%, and arterial blood gas analysis showed PaO2 of 60.5 mmHg and PaCO2 65.0 mmHg. To our knowledge, this is the first case of CMT accompanied by rigid spine and respiratory failure. Motor and sensory neuropathy combined with rigid spine also have not been reported previously. The relationship between rigid spine syndrome with neurogenic muscular atrophy and CMT type 2C with the clinical characteristics of diaphragm and vocal cord paresis is discussed.     

Giant axonal neuropathy: clinical, electrophysiologic, and neuropathologic features in two siblings

Giant axonal neuropathy is a progressive central-peripheral axonopathy characterized by distention of axons by aggregated neurofilaments. We report two female siblings with giant axonal neuropathy. Both patients developed symptoms of a chronic progressive polyneuropathy at age 3 years. Clinical evidence of central nervous system involvement was present in both cases. Autopsy neuropathologic examination of the older sibling at the age of 11 years revealed numerous giant axons, Rosenthal fibers, and gliosis throughout the brain and spinal cord and typical giant axons in the peripheral nerves. Electrophysiologic studies in the younger sibling indicated brain stem dysfunction, and her sural nerve biopsy revealed enlarged axons packed with neurofilaments. These patients illustrate that neurologic deficits of giant axonal neuropathy result from widespread lesions in the central, as well as peripheral (including autonomic), nervous systems. This occurrence of giant axonal neuropathy in two siblings supports a genetic origin of this disease. This is the first report of autopsy findings in giant axonal neuropathy in an affected sibling.     

Congenital muscular dystrophy with severe infantile scoliosis

A girl with congenital muscular dystrophy with severe scoliosis from birth was presented. No positive family history was obtainable. She developed muscle hypotonia and weakness, and feeding difficulty during the neonatal period. Her developmental milestones were delayed; she learned to walk at the age of 2 years when she walked with a "waddling gait" and stood up with Gowers' maneuver. On physical examination at 2 years old, she had mild proximal dominant muscle weakness and atrophy, and severe scoliosis with a Cobb's angle of 74 degrees but no joint contractures in the extremities. Creatine kinase was slightly elevated. Biopsied muscle showed myopathic changes, including variation in fiber size, moderate fibrous tissue proliferation, some necrotic and regenerating fibers and type 1 fiber predominance, consistent with those seen in chronic progressive muscular dystrophy.     

Chronic inflammatory demyelinating polyradiculoneuropathy associated with multifocal nerve hypertrophy--report of a case with MRI study]

We reported a 29-year-old woman who had chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) associated with multifocal nerve hypertrophy. She developed chronic progressive muscular weakness of distal part of her extremities and sensory ataxia of limbs and trunk for five years. Steroid therapy improved most of her signs and symptoms. No recurrence has occurred for the subsequent four years until present time. Magnetic resonance imaging (MRI) revealed multifocal and nodular hypertrophy of her peripheral nerves in the extremities. MRI also detected the hypertrophy of posterior nerve ganglia and extradural nerve roots. Hypertrophic nerve trunk comprised of multifocal and nodular hypertrophy of the nerve fiber fascicles which were detected as abnormal high signal intensity area in MR T2-weighted images. Her sural nerve contained no onion-bulb formations and presented normal low signal in MR T2-weighted images. We concluded that the hypertrophic changes occurred multifocally in and among nerve fascicles predominantly at the proximal part of the nerves of the extremities. MRI is useful method to detect the hypertrophic change of peripheral nerves deep in the trunk and the extremities in CIDP.     

Cervical root avulsion presenting proximal segmental muscular atrophy of unilateral upper extremity]

A 56-year-old woman noticed non-progressive weakness in the proximal part of the right upper extremity from her childhood. At the age of 37 years, she was diagnosed as "spinal muscular atrophy" by an orthopedic surgeon. At the age of 56, neurological examinations revealed muscular atrophy and weakness confined to the right deltoid, biceps brachii and brachioradialis together with minor sensory disturbance in the lateral side of the right shoulder and forearm without pyramidal sign in the lower extremities. The neurological features of this case differed from those of juvenile type of distal and segmental muscular atrophy of upper extremities in distribution of muscular atrophy, and simulated those of cervical spondylotic amyotrophy. Myelography demonstrated root avulsion of the right C5 and C6 roots. CT myelography revealed traumatic meningocele. Therefore a clinical diagnosis of cervical root avulsion resulting from unrecognized birth injury was made. The reason of motor dominant pictures of this case may be vulnerability of the anterior nerve roots to traction injury.     

A manifesting carrier of Duchenne muscular dystrophy presenting mosaic distribution of dystrophin negative and positive muscle fibers

A 25-year-old female patient with an approximate 10-year-history of slowly progressive muscle weakness was diagnosed as a manifesting carrier of Duchenne muscular dystrophy (DMD) because her muscle biopsy showed scattered fibers with no dystrophin on immunohistochemical staining. She had no family history of neuromuscular disorders. She was in good health until about 14 years of age, when she developed muscle weakness and atrophy of the extremities with slow aggravation. On admission at the age of 25 years, she had asymmetrical muscle atrophy in the lower extremities; the left femur, right femur, left crus, and right crus measured 36.0, 40.5, 31.5, and 35.5 cm in circumference, respectively. However, the muscle weakness of the extremities was symmetrical with no laterality, and the proximal muscles in the lower extremities were predominantly affected to 3+/5 MMT test. She walked with a mild wadding manner and stood up with Gower' maneuver. Deep tendon reflexes of the extremities were almost normoactive with no pathologic reflexes. As to laboratory findings, serum enzymes of muscular origin were elevated; GOT was 44 IU/l, GPT 60 IU/l, LDH 829 IU/l, CK 4238 IU/l, and aldolase 31 SL units. The electromyogram showed myopathic changes mixed with some neurogenic components. Peripheral nerve conduction velocity was normal. A computed tomography of the skeletal muscles showed more marked atrophy and lower density in the left lower extremity than in the right. The biopsied left gastrocnemius muscle demonstrated a marked variation in fiber size with some necrotic and regenerating fibers. On immunohistochemical stain with anti-dystrophin antibody, the dystrophin negative fibers were scattered among positive fibers in a mosaic distribution.     

Dejerine-Sottas disease with a novel de novo dominant mutation, Ser 149 Arg, of the peripheral myelin protein 22

The Ser149Arg mutation of peripheral myelin protein 22 (PMP22) was found in a 19-year-old woman with a sporadic case of Dejerine-Sottas disease. The patient showed delayed motor development. She walked for the first time with support at the age of 2 years. Scoliosis developed at age 4 years. Her walking ability was best at age 11. Thereafter, she showed progressive muscle weakness and sensory disturbances in the distal extremities. At the age of 18 years, the use of a wheelchair became necessary. Motor and sensory nerve conduction studies showed absent motor and sensory responses on electrical stimulation of the limb nerves. A sural nerve biopsy specimen showed marked decreases in the numbers of both large and small myelinated fibers, abundant onion-bulb formation, and hypomyelination. Electron microscopic observation revealed the presence of demyelinated axons and myelin sheaths disproportionately thin relative to axon diameter. That this was a de novo mutation was established by parentage testing and PMP22 gene analysis of the parents. The mutation seems to be novel and dominant. Received: 12 April 1999 / Accepted: 14 June 1999     

A female infant of mitochondrial myopathy with findings of active necrosis and regeneration of muscle fibers

An 8 year-old female infant with the clinical and pathological characteristics of both progressive muscular dystrophy and mitochondrial myopathy was described. Her maternal cousin had clinical and pathological findings of Duchenne muscular dystrophy (DMD). Since the patient had markedly elevated serum CK and calf muscle hypertrophy, her muscle was biopsied and she was diagnosed as having female DMD at the age of 5 years. She had generalized tonic-clonic convulsions and alternate hemiconvulsions for recent 4 years which brought her our hospital. On admission, she had mild generalized muscle atrophy and weakness predominantly in the proximal limbs. The lactate and pyruvate levels in both serum and cerebrospinal fluid were elevated, but with no metabolic acidosis. Serum CK was elevated to 4464 IU/L. Brain CT and MRI showed the expanding arachnoid cyst in the left middle fossa of cranium. In the biopsied left biceps crachii muscle, in addition to numerous ragged-red fibers, there were active muscular fiber necrosis and regeneration and interstitial fibrosis similar to those seen in progressive muscular dystrophy. Biochemically, no decrease or defect in the respiratory chain enzymes was detected. On electron microscopy, a large number of fibers contained aggregates of giant mitochondria with proliferated complicated cristae. Scattered throughout were necrotic muscle fibers filled with phagocytes and regenerating fibers. This patient had the diagnostic features of mitochondrial encephalomyopathy and progressive muscular dystrophy. We supposed that the patient provided very interesting evidences to study the relationship between mitochondrial myopathy and progressive muscular dystrophy.     

Growth of segmental nerves to the developing rat diaphragm: absence of pioneer axons

A study has been made of the growth of cervical nerves C3-C6 to the rat diaphragm. At 11 days of embryonic age these cervical nerves first project out of the spinal cord toward the cardinal veins and later form the left and right phrenic nerve trunks. During the next 2 days, the phrenic nerves grow caudally in close association with the cardinal veins toward the diaphragm. At the growing tips of these nerve trunks the growth cones of axons were observed every 1-2 micrometers. The last axon did not project more than 2 micrometers ahead of any neighbouring axons. At 14 days the phrenic nerves reach the level of the developing diaphragm and converge into pools of premuscle cells. Previous studies have suggested that the phrenic nerve enters the premuscle masses of the diaphragm at an early developmental stage when the premuscle masses are at approximately the segmental levels C3-C6. This study shows that the phrenic nerves must grow to more caudal levels in order to reach the premuscle cells of the diaphragm. Furthermore, the leading axons of the phrenic nerve trunk do not project in a pioneering fashion, far in advance of the trailing axons.     

Giant neural systems in the inner retina and optic nerve of small whales

Giant neural cell systems (dendrites, cell bodies, and axons) are present among more usual structures in the retina and optic nerve of the small whale (dolphin) Tursiops truncatus retina. Giant cell body dimensions range up to 75 μm in diameter. Nuclei of the cells are frequently larger (>20 μm) than nearby ganglion, bipolar, and receptor cell bodies. The presence of the giant cell system and giant elements in the nerve fiber layer agree with the unusually broad fiber spectrum of the dolphin optic nerve where more than 6% of the axons are >15 μm in diameter. Smaller axons in the size distribution are typical of dimensions found in terrestrial mammals. The axon estimate totaled 157,000 per optic nerve. The giant cell-axon systems of the whale retina may be a unique expression of the large ganglion cell-axon (transient or “Y” functional unit) systems recently identified in terrestrial mammals.     

Autosomal dominant adult-onset spinal muscular atrophy with vocal cord paralysis: a case report]

This report concerns a 41-year-old female case of spinal muscular atrophy (SMA) associated with vocal cord paralysis. Her parents were not consanguineous. Her maternal grandmother and younger brother were suspected of having SMA. At age 37, she first experienced gait disturbance and began to have slowly progressive dysarthria and weakness of the extremities. Neurological examination revealed that she had inspiratory stridor, dysarthria and proximal muscular weakness of the extremities. Achilles tendon reflexes were absent, while there were no pathological reflexes or sensory disturbances. She showed a waddling gait and Gowers' sign. The laboratory data indicated mild elevation of serum CK. The nerve conduction study was normal, while the electromyographic study and muscle biopsy revealed neurogenic changes. We diagnosed the case as adult onset SMA of the autosomal dominant type. Laryngoscopy revealed that the patient had vocal cord paralysis, which was predominant in abductor muscles and of the posterior paralysis type according to the categories established by Isozaki. Genetic analysis showed no mutations in the genes of the neuronal apoptosis inhibitory protein and of the survival motor neuron.     

新生儿型神经轴索营养不良的皮肤神经和肌肉病理改变

目的　报道2例新生儿型神经轴索营养不良(INAD)的神经末梢和骨骼肌的病理改变特点。方法　2例患者均为男性,年龄分别为3岁及2岁,均于1岁左右出现智力和运动发育落后或倒退,头颅磁共振成像(MRI)均示小脑萎缩。肌电图提示骨骼肌神经源性损害。例1进行左侧腓肠神经、肌肉和皮肤活检,例2进行左小腿皮肤和肌肉活检,标本进行光镜和电镜检查。结果　2例患者皮下神经末梢均可见椭圆体状巨大轴索,其内充满空泡或致密物质。例1腓肠神经偶见小的致密轴索。例2的骨骼肌间小神经发现异常巨大轴索。两例骨骼肌均存在神经源性病理改变。电镜发现巨大轴索内存在颗粒样物质或空泡膜管样结构。结论　出现中枢神经系统、周围神经系统以及视神经的广泛受累提示INAD的可能性,而脑外病理检查发现神经末梢出现椭圆体样巨大轴索可以确诊该病。巨大轴索内的成分具有不同的超微结构特点。显著的皮肤神经末梢损害提示此病存在小纤维性周围神经病。     

Degenerative changes at the neuromuscular junctions of red, white and intermediate muscle fibers. Part 1. Response to short stump nerve section

Degeneration at the neuromuscular function following cutting the phrenic nerve at the 9th intercostal space differs in red, white and intermediate skeletal muscle fibers. The ultrastructure of the nerve terminal and the muscle fiber between 12 hours and 21 days following denervation suggests that lack of neurotrophic influences results in responses specific for each fiber type. Degeneration of axon ends is rapid and by 2 days axon terminals are missing from the end-plate areas of all 3 fiber types. Schwann cells "engulf" degenerating axon terminals and eventually replace them in the primary clefts. Schwann cells display specific morphological changes directly related to axonal degeneration. In all instances axon terminal degeneration precedes muscle fiber degeneration. Synaptic cleft changes are similar for all types of muscle fibers. Primary cleft structure appears to be dependent upon neurotrophic influence, whereas secondary cleft structure is relatively unaffected by denervation. Initial changes in subsynpatic regions of muscle fibers include focal loss of sarcomere alignment and skewing of the Z lines. By 21 days myofibrillar disorganization appears most severe in white fibers and least in red muscle fibers. The rate and degree of degeneration of the axon terminal and subjacent muscle fiber are different for each of the 3 muscle fiber types.     

线粒体融合蛋白2基因新突变导致的遗传性运动感觉性神经病6型一家系

目的 报道1个遗传性运动感觉性神经病6型家系的临床表现、病理改变以及基因突变特点。方法 先证者男性,15岁。患者5岁出现双下肢无力,症状进行性加重,伴随出现双足跟腱挛缩;11岁开始出现慢性进行性视力下降;12岁出现双手肌肉萎缩,无肢体麻木。周围神经传导速度检查显示诱发电位未能引出或波幅显著下降,感觉神经较运动神经改变更明显。视诱发电位提示双眼P100潜伏期均延长,波幅正常。眼底照相提示视神经萎缩,视网膜电图正常。患者母亲7岁时开始出现走路费力,10岁出现视力下降。对先证者进行腓肠神经活体组织检查。对先证者及其母亲进行线粒体融合蛋白2( MFN2)基因测序,100名健康人作为正常对照。结果 腓肠神经病理改变主要为有髓神经纤维显著减少,电镜检查发现个别有髓神经纤维出现洋葱球样结构和再生簇结构,个别神经纤维的轴索内可见线粒体聚集和空泡化。先证者和母亲的MFN2基因第19号外显子存在c.2218T＞C杂合突变,导致MFN2第740位的色氨酸由精氨酸替代(W740R)。100名健康对照没有发现该突变。结论 MFN2基因c.2218T＞C突变导致了遗传性运动感觉性神经病6型,其视力下降多出现在脊神经损害之后,周围神经可以存在髓鞘损害。     

A case of senile onset rimmed vacuole myopathy with proximally dominant involvement

A 73-year-old woman with progressive proximal-dominant muscular atrophy and weakness was described. She had been well until 70-year-old, when she found difficulty in standing up from sitting position. At age 72 years, she could not raise her arms. Neurological examination showed muscular wasting and weakness in the proximal parts of extremities, shoulder and pelvic girdle. In the thigh, the flexors and adductors were severely affected. Muscular weakness was also observed in m. tibialis anterior. Serum CK and aldolase were normal. Electromyography showed low voltage short duration motor unit potentials with positive sharp waves and fibrillations. Rimmed vacuoles were observed in 4.8% of muscle fibers in biopsy sample obtained from right m. quadriceps femoris. No inflammatory cells, PAS-positive materials and inclusion bodies were observed in the sample. This case differs from distal myopathy with rimmed vacuoles, because the onset was very late and her muscular weakness and atrophy was proximal dominant. This case also differs from inclusion body myositis, because muscle biopsy revealed no inflammatory cells or inclusion body.     

Synaptic and axonal remodeling of mossy fibers in the hilus and supragranular region of the dentate gyrus in kainate-treated rats

Seizures evoked by kainic acid and a variety of experimental methods induce sprouting of the mossy fiber pathway in the dentate gyrus. In this study, the morphological features and spatial distribution of sprouted mossy fiber axons in the dorsal dentate gyrus of kainate-treated rats were directly shown in granule cells filled in vitro with biocytin and in vivo with the anterograde lectin tracer Phaseolus vulgaris leucoagglutinin (PHAL). Sprouted axon collaterals of biocytin-filled granule cells projected from the hilus of the dentate gyrus into the supragranular layer in both transverse and longitudinal directions in kainate-treated rats but were not observed in normal rats. The sprouted axon collaterals projected into the supragranular region for 600–700 μm along the septotemporal axis. Collaterals from granule cells in the infrapyramidal blade crossed the hilus and sprouted into the supragranular layer of the suprapyramidal blade. Sprouted axon segments in the supragranular layer had more terminal boutons per unit length than the axon segments in the hilus of both normal and kainate-treated rats but did not form giant boutons, which are characteristic of mossy fiber axons in the hilus and CA3. Mossy fiber axons in the hilus of kainate-treated rats had more small terminal boutons, fewer giant boutons, and there was a trend toward greater axon length compared with mossy fibers in the hilus of normal rats. With the additional length of supragranular sprouted collaterals, there was an overall increase in the length of mossy fiber axons in kainate-treated rats. The synaptic and axonal remodeling of the mossy fiber pathway could alter the functional properties of hippocampal circuitry by altering synaptic connectivity in local circuits within the hilus of the dentate gyrus and by increasing the divergence of the mossy fiber terminal field along the septotemporal axis. J. Comp. Neurol. 390:578–594, 1998. © 1998 Wiley-Liss, Inc.     

A patient with motor neuron syndrome clinically similar to amyotrophic lateral sclerosis, presenting spontaneous recovery]

We report a patient with motor neuron syndrome similar to amyotrophic lateral sclerosis (ALS) and with spontaneous recovery. At the age 40, the woman developed progressive muscular weakness, atrophy and fasciculation in extremities. She also noted a dyspnea, tongue atrophy and dysphagia. A neurological examination 6 months after onset revealed i) a tongue atrophy and fasciculation, ii) diffuse muscule weakness and atrophy in face, neck and extremities, and iii) marked hyperreflexia in the four limbs and bilateral Babinski reflex, but iv) neither sensory disturbance nor ophthalmoplegia. Electromyogram (EMG) detected such denervation potentials as fibrillation potentials, fasciculation potentials, positive sharp waves and polyphasic or giant MUPs diffusely in the limb muscles. Peripheral nerve conduction study detected neither conduction block nor delay. Thus, she was diagnosed as suffering from ALS. However, since approximate 1 year after onset, her muscle weakness has gradually been getting better. Simultaneously, the dyspnea and dysphagia gradually improved. Two years after onset, an EMG examination detected chronic denervation potentials in the left musculus sternocleidomastoideus and a few on-going denervation potentials in the left musculus extensor carpi radialis, but no denervation potentials in other limb muscles. Fasciculation potentials were found in tongue muscles. Thus, the present case was thought to have a reversible motor neuron syndrome clinically quite similar to ALS. A mild increase in IgE (346 U/ml) and a low-titer IgM-class anti-GM1 antibody were found in her serum though its pathological significance was uncertain. Any immunological aberrance may account for the pathogenesis. It should be noted that clinically diagnosed cases of ALS may rarely recover spontaneously.     

Axons grow in the aging rat but fast transport and acetylcholinesterase content remain unchanged

Caliber and microtubular density of myelinated fibers, acetylcholinesterase (AChE) content and its accumulation at a ligature were studied in the phrenic nerve of mature (3-4 months) and aging (2-year-old) rats. The number of axons remained constant. The cross-sectional area of the nerve was 67% greater in the older group; the axoplasm, though, constituted about 20% of the nerve tissue irrespective of age. The mean cross-sectional area of myelinated axons was twice as big in aging compared to mature rats. All axons grew in the same proportion irrespective of their original caliber. The microtubular density of 3-microns axons was about 22 microtubules/micron2 in mature and aging rats. The AChE activity of aging rats was half as much as that of mature rats if it was expressed per wet weight of nerve tissue but did not change if it was expressed per nerve fiber. Twenty-four hours after ligation of the nerve, total AChE activity rose in mature and aging rats by ca. 168%; the molecular forms--asymmetric and globular--accumulated in the same proportion in both age groups. We conclude that myelinated axons grow in the adult stage of life but the structure of axoplasm, content of AChE per axon, and rate of fast transport remain lifelong features of nerve fibers.     

Sequential neuroradiological and neurophysiological studies in a Japanese girl with merosin-deficient congenital muscular dystrophy

We describe the early manifestation and sequential assessment of the central and peripheral nervous system in a Japanese girl with merosin-deficient congenital muscular dystrophy. She showed severe hypotonia (‘‘floppy infant”) and suffered mild respiratory failure postnatally. Serum creatine kinase was elevated to 11,487 IU/L. The muscle biopsy showed dystrophic changes with negative expression of merosin (laminin α2), thereby confirming merosin-deficient congenital muscular dystrophy. Her motor milestones were severely delayed, but she could sit without support at the age of 3 years. After 3 years, her motor ability deteriorated and by the age of 5 years, she could not sit and control her neck. Magnetic resonance imaging (MRI) at 2 months of age revealed patterns that were appropriate for her age. At 1 year of age, the T2 weighted images showed diffuse high signal intensities throughout the centrum semiovale, and periventricular and subcortical white matter of the frontal and occipital lobes, while the U fibers, the corpus callosum and the internal capsule were spared. At the age of 7 years, these white matter abnormalities decreased. MR spectroscopy (MRS) revealed normal values of N-acetylaspartate (NAA)/creatine (Cr) and choline (Cho)/Cr metabolite ratios as well as slightly increased myoinositol (mI)/Cr metabolite ratios. Neurophysiological motor nerve conduction velocity (MCV) and compound muscle action potential (CMAP) of the median nerve were in the normal range at the age of 2 months. After the child reached 1 year of age, the MCV and CMAP lagged behind those of healthy controlled children. The sensory nerve conduction velocity of the median nerve demonstrated a mild delay at the age of 15 months. It improved to normal range at the age of 6 years but decreased at 7 years of age. These sequential findings suggest not only that muscular degeneration and dysmyelination had occurred but also that various other factors, including demyelination and the vasogenic system, may influence the pathology of MDC1A.