Selective type II muscle fiber hypertrophy in severe infantile spinal muscular atrophy

The diagnostic muscle biopsy finding in severe infantile spinal muscular atrophy (Werdnig-Hoffmann disease, SMA type 1) is considered to be large-group atrophy with isolated clusters of hypertrophic type I myofibers. We present a unique case of severe infantile spinal muscular atrophy with selective hypertrophy of type II myofibers. A male infant presented at age 2 months with breathing difficulties and by age 4 months was hypotonic and weak. Electromyography revealed denervation in all extremity muscles, and nerve conduction velocities were normal but with small compound muscle action potentials. Quadriceps muscle biopsy revealed many hypertrophied type II myofibers (myofibers with a mean least diameter of 25.4 microns). In contrast, the largest type I myofibers were 20 microns in least diameter (mean diameter, 14.9 microns), and there was a normal-size population of type II fibers (mean diameter, 15.7 microns). In addition, sheets of atrophic type I and type II fibers averaged 2.0 microns in least diameter. Sural nerve biopsy was normal. Breathing difficulties progressed, with death ensuing at age 5 1/2 months. Autopsy revealed atrophy of ventral spinal roots with normal dorsal roots. There was loss of anterior horn cells, while remnant neurons were reduced in size. No other pathologic changes were identified. This case indicates that in severe infantile spinal muscular atrophy, relative sparing of the motor units with type II myofibers may occur.     

Acute onset of infantile spinal muscular atrophy

Two patients with acute generalized weakness and areflexia are presented. The electrophysiologic studies in both revealed evidence of decreased conduction velocity and mixed axonal and demyelinating neuropathy, suggestive of the diagnosis of Guillain-Barré syndrome. The young ages of the patients and their failure to respond to immunoglobulin therapy were the major clues to the final diagnosis of spinal muscular atrophy type I. Blood for DNA study revealed homozygous deletion mutation in exons 7 and 8 of the survival motor neuron gene. This diagnosis should be considered in every child under 1 year of age who presents with acute weakness because Guillain-Barré syndrome in this age group is rare.     

婴儿型脊髓性肌萎缩症的临床及电生理特点

目的 探讨婴儿型脊髓性肌萎缩症(SMA)的临床和电生理特点.方法 回顾性分析20例婴儿型SMA患儿的临床资料.结果 20例SMA患儿临床表现为出生后进行性加重的四肢弛缓性瘫痪,肌张力低下,腱反射消失.肌电图表现为神经源性损害,所检测的50条运动神经均示神经肌肉复合动作电位波幅衰减,其中10条合并末端潜伏期延长及传导速度轻度减慢;所检测的25条感觉神经传导速度在正常范围.肌肉活检为典型的神经源性肌萎缩.结论 婴儿型SMA的临床特点为出生后进行性加重的四肢弛缓性瘫痪,肌电图检查显示为神经源性损害.     

4例婴儿型脊肌萎缩症家系临床病理分析

目的：分析4例阳性家庭史的婴儿型脊肌萎缩症患儿临床病理表现，探讨本病的临床病理特点及早期诊断要点。方法：回顾分析4例经病理学检查证实的婴儿型脊肌萎缩症患儿的临床资料及病理学改变。结果：患儿多在1岁内起病，呈进行性弛缓性对称性四肢瘫痪，以下肢、近端明显，血清CPK、LDH正常。肌电图为失神经性支配。肌活检呈神经性肌萎缩，常累及整个肌束。本组患儿3例死亡，1例瘫痪。结论：确诊本病应结合临床特点，肌电图表现及神经肌肉活检改变等，这些在鉴别诊断中有重要价值，为进一步基因检测研究奠定了基础。     

Sensory system involvement in infantile spinal muscular atrophy.

Nine cases of infantile spinal muscular atrophy were studied post-mortem. Their ages at death ranged from 5 months to 10 years. In all cases severe loss of anterior horn cells in the spinal cord and neurogenic muscular atrophy were characteristic of this disease. In 6 cases there was also loss of myelin in the posterior columns particularly affecting the lumbar contribution. Sensory ganglia, especially from the lumbar region, contained nodules of Nageotte, indicating sensory neuron degeneration. These sensory abnormalities were more severe in the longer surviving cases. It seems possible that sensory neuron degeneration occurs more commonly in Werdnig-Hoffmann disease than has previously been supposed but that it is less severe and develops more slowly than motor neuron degeneration.     

Serum cholinesterase activity in infantile and juvenile spinal muscular atrophy

Serum acetylcholinesterase (AChE) and pseudocholinesterase (ChE) activity in infantile and juvenile spinal muscular atrophy (SMA) was determined. The total AChE activity was either normal or decreased in the childhood SMA (Type 1), the other SMA groups and disease controls (ALS, X-linked SMA). In the majority of SMA Type 1 cases (6/7 tested) an absence of the asymmetric A12 form was found. This was accompanied by changes in the other asymmetric and globular forms. The latter was, however, not specific for SMA Type 1 cases. The ChE activity was increased in the majority of SMA cases as well as disease controls. The asymmetric A12 ChE form was increased in all SMA Type 3 cases, the values of this form in SMA Type 1 was variable. A change in the ChE globular forms in SMA Type 1 and SMA Type 2 was a frequent finding. It is suggested that the absence of the asymmetric A12 AChE form in SMA Type 1 arises because of muscle cell immaturity and undeveloped muscle-nerve interactions. The reason of ChE changes is obscure.     

Neonatal adrenoleukodystrophy presenting as infantile progressive spinal muscular atrophy

Two siblings with neonatal adrenoleukodystrophy are described. The signs and laboratory data documenting infantile progressive spinal muscular atrophy included the initial presentation of 1 sibling with neonatal adrenoleukodystrophy. These patients indicate that neonatal adrenoleukodystrophy should be considered in the differential diagnosis of infantile progressive spinal muscular atrophy.     

婴儿型脊肌萎缩症22例临床分析

目的 探讨婴儿型脊肌萎缩症的发病机制、临床与病理特征及诊断.方法 对22例确诊为婴儿型脊肌萎缩症患者的临床表现、实验室资料、病理资料进行了回顾性分析.结果 本病临床特点患儿大多为8个月内起病,四肢呈对称性、迟缓性瘫痪,下肢重于上肢,近端重于远端;有肌萎缩,血清CK、LDH正常或增高;肌电图显示神经源性损害,肌活检见肌纤维萎缩、变性、坏死,符合脊肌萎缩症的改变.结论 婴儿型脊髓性肌萎缩症有较典型的临床及电生理特征,肌电图检查是重要的诊断方法,肌活检可为脊肌萎缩症的诊断提供客观的诊断依据,目前对本病主要采取对症治疗.     

Progressive infantile spinal muscular atrophy. Report of 12 cases

Twelve children with progressive spinal muscular atrophy were seen at Santo Antonio Children Hospital, Porto Alegre. Diagnosis was based on neurological evaluation, serum enzymes, electroneuromyography and muscle biopsy. Several aspects are discussed by the authors, especially those concerning the presentation mode of the illness and the laboratory investigation. Our results are reviewed under the light of the current literature.     

Muscle biopsy and the clinical course of infantile spinal muscular atrophy

Eight infants with severe early infantile spinal muscular atrophy diagnosed by clinical presentation and muscle biopsy were studied. The extent of alterations in muscle histology, histochemistry, and ultrastructure did not reflect the relative severity of the clinical presentation or the course of the illness. In seven biopsies, ultrastructural studies demonstrated empty sleeves of basal lamina projecting from the surface of small myofibers. We conclude that severe infantile spinal muscular atrophy often results in myofiber atrophy similar to that found in other motor neuron diseases, and it is not solely a hypotrophic process. Muscle biopsy findings are important because they help to establish the diagnosis, but they do not help predict the severity of disease among infants with this condition.     

Infantile olivopontocerebellar atrophy with spinal muscular atrophy (infantile OPCA + SMA)

We report three siblings (two boys and girl) with familial (autosomal recessive) infantile olivopontocerebellar atrophy (OPCA) associated with lower motoneuron involvement. Brain autopsy findings in two of the children revealed a multisystem degeneration characterized by marked hypoplasia of phylogenetically new parts of the brain stem (basis pontis and inferior olivary nuclei) associated with hypoplasia of the neocerebellum, both cerebellar and cerebral peduncle. All three infants died before six months of age. The clinical features are characterized by severe hypotonia, areflexia, failure to thrive, respiratory insufficiency in all cases, cardiomyopathy and dislocated hips at birth in two of the three siblings. Extensive serum, urinary and leukocyte enzyme assays in the second infant failed to disclose a specific metabolic abnormality. The diagnosis of OPCA was established prior to death by Magnetic Resonance Imaging (MRI) in the youngest infant. Since OPCA represents a heterogeneous group of diseases, correlation of neuropathologic, clinical, genetic and MRI findings at early stages of evolution becomes crucial in the understanding of the nosology of OPCA and its variants.     

Digital necroses and vascular thrombosis in severe spinal muscular atrophy

Internal jugular vein catheterization has been implicated in spinal accessory nerve (SAN) injuries after coronary artery bypass grafting (CABG). Stretch injury due to prolonged positioning during CABG has also been proposed as another mechanism of injury. Herein we describe a male patient with left shoulder pain and abduction difficulty following CABG, who displayed electromyographic abnormalities confined to the left upper trapezius muscle. Internal jugular vein catheterization had not been performed during surgery. Although unusual, the possibility of upper trapezius muscular branch paralysis should be considered in patients with shoulder pain or weakness after CABG. Muscle Nerve, 2010     

Incidence of infantile spinal muscular atrophy on Shikoku Island of Japan

Background

Spinal muscular atrophy (SMA) is an autosomal recessive disorder caused by homozygous mutations in the SMN1 gene. SMA has long been known to be the most common genetic cause of infant mortality. However, there have been no reports on the epidemiology of infantile SMA (types 1 and 2) based on genetic testing in Japan. In this study, we estimated the incidence of infantile SMA on Shikoku Island, which is a main island of Japan and consists of four prefectures: Ehime, Kagawa, Tokushima and Kochi.

Genetic investigations on chronic forms of infantile and juvenile spinal muscular atrophy

Summary A material of 247 cases selected from 260 cases of spinal muscular atrophy in the Warsaw Department of Neurology in 1960–1974 was analyzed. The size of sibships was established and calculations were made of the mean distribution of the age at onset, also according to sex, for the different clinical forms, genetical proportions by the method of siblings and of probands, and coefficient of sib-sib correlation for the material as a whole and separately for males, femals and male-female pairs.The analysis shows the course of the disease to differ between the sexes and to be mild in males more often than in females, as is particularly noticeable in the higher age groups. Cases of Kugelberg-Welander's disease are predominantly male. The hypothesis is advanced that a proportion of male patients have a sex-linked modifying gene of a fairly high frequency (possibly of the range of 1 in 5 males, and 1 in 25, in the homozygous state, in females).Although it would not disprove conclusively the nosological distinctness of different forms of infantile and juvenile spinal muscular atrophy, the existence of the modifying gene, if proved, would tend rather to add to the likelihood of their constituting a single recessive autosomal disease.From Genetic Laboratory of Institute of Psychoneurology.     

Computed tomography of the skeletal musculature in Becker-type muscular dystrophy and benign infantile spinal muscular atrophy

Results of computed tomographic (CT) examination of the skeletal musculature in 26 patients with Becker-type muscular dystrophy (BMD) and 12 patients with benign infantile spinal muscular atrophy (BISMA) are presented. Both disorders revealed strikingly different changes that may have important clinical significance. First, in BMD, CT abnormalities consisted of areas of decreased densities, at first appearing in part of the muscle, and then gradually spreading until the whole muscle was replaced by low-density tissue. In BISMA, however, low-density lesions were scattered throughout the muscle. Second, in BMD, some muscles were preferentially affected in an early stage of the disease and others were relatively spared, whereas in BISMA, the muscles were involved more or less simultaneously. Third, an enlargement in size (hypertrophy) was frequently observed in BMD in various muscles of the legs, whereas in BISMA, this phenomenon can sometimes be noted only in the gastrocnemius muscles.