Brain magnetic resonance imaging abnormalities in merosin-positive congenital muscular dystrophy.

We report the brain magnetic resonance imaging (MRI) findings in 23 patients with merosin-positive congenital muscular dystrophy (CMD). Twelve patients had normal scans. Eight other children had essentially normal scans but showed mild non-specific periventricular white matter changes. Three children had structural abnormalities on imaging. The first patient, a 15-month-old boy with hypotonia, muscle weakness and global development delay, had moderate cerebellar atrophy and mild dilatation of the lateral ventricles. The second child, a 3-year-old ambulant girl with subtle learning problems, had mild cerebellar hypoplasia and a large subarachnoid space when scanned at 16 months. The third patient, a 15-year-old ambulant male with normal intelligence and complex partial seizures, had polymicrogyria of both temporoparietal lobes on brain MRI. The clinical features and motor ability of children with merosin-positive CMD are variable, although usually milder than merosin-deficient CMD. Our findings confirm that central nervous system involvement can occur in some merosin-positive cases. We suggest performing brain MRI in children with merosin-positive CMD, as this may help in our understanding of this very heterogeneous disease.     

LAMA2 stop-codon mutation: Merosin-deficient congenital muscular dystrophy with occipital polymicrogyria,epilepsy and psychomotor regression

Merosin-deficient congenital muscular dystrophy (MD) type 1A (MDC1A) is one of the most frequent forms of CMD in Western countries.The classical form, characterized by a total lack of laminin α2 chain expression, usually shows severe clinical features; cases with complete laminin α2 deficiency and mild phenotype have also been reported, although the mechanisms underlying the lack of genotype–phenotype correlation have not been elucidated. Epilepsy and focal cortical dysplasia—in addition to the classical diffuse white matter abnormalities—have been described in some of these patients associated with cognitive deterioration.We report on a patient with total laminin α2 deficiency due to a homozygous stop-codon mutation in the LAMA2 gene, with mild evolution. When 6.9 years old, she developed focal occipital seizures and absence-like status when awake, with probable relation to an extensive bilateral occipital micropolygyria. Soon afterwards she lost ambulation and developed cognitive deterioration.Our case confirms that the clinical spectrum of MDC1A is more heterogeneous than previously thought.     

先天性肌营养不良的诊断及层黏连蛋白表达的意义

目的 探讨先天性肌营养不良（CMD）的临床诊断、肌肉免疫组织化学特点及随访情况。方法 对8例CMD患儿的病例资料进行综合分析,并进行肌肉活检,利用抗层黏连蛋白以（laminin α2,又称merosin）、α抗肌萎缩相关糖蛋白（α-dystroglycan,α-DG）和β抗肌萎缩相关糖蛋白（β-dystroglycan,β-DG）抗体行肌肉活检组织免疫组织化学染色。结果 8例均于出生时或生后半年之内出现肌无力、肌张力低下,有的合并关节挛缩、喂养困难或呼吸功能不全。肌肉病理检查均发现肌营养不良改变特点。其中merosin染色阴性者4例,头颅MRI示脑白质髓鞘化不良;4例为merosin染色阳性,呈散发或常染色体隐性遗传,2例合并有智力低下,抗α-DG（1IH6）抗体染色显示α-DG糖基化低下,其中1例伴视神经萎缩,头颅MRI提示脑结构异常。结论 本组CMD中merosin染色既有阴性,也有阳性,merosin缺乏症（先天性肌营养不良1A型）更为常见,伴随脑白质病变。merosin染色阳性者中存在抗肌萎缩相关糖蛋白糖基化低下病例。     

Clinical and Histopathological Study of Merosin-deficient and Merosin-positive Congenital Muscular Dystrophy

The clinical features of merosin-positive congenital muscular dystrophy (CMD) and merosin-deficient CMD are well known, with those of merosin-deficient CMD being more severe. Whether the severity of histopathological findings correlates with these clinical features remains unanswered. In this study, the clinical and histopathological findings of 39 merosin-deficient and 37 merosin-positive CMD patients were compared. Merosin-deficient CMD patients were found to be younger, with earlier onset of symptoms, age of diagnosis, and a more severe clinical state (reflecting maximum motor capacity and contractures). On histopathological evaluation, endomysial fibrosis, perimysial fibrosis, and histopathological state (reflecting fibrosis, adiposis, necrosis, and variation in fiber size) were more severe in merosin-deficient CMD. There was a correlation between clinical and histopathological states only in merosin-deficient CMD. Received January 15, 1999; accepted April 7, 1999.     

Merosin-deficient congenital muscular dystrophy (CMD): a study of 25 Brazilian patients using MRI

Background: Merosin-deficient congenital muscular dystrophy (CMD) is characterized clinically by hypotonia and muscular weakness and, on imaging studies, by white matter (WM) abnormality. Objective: To evaluate MRI findings in Brazilian patients with merosin-deficient CMD. Materials and methods: Twenty-five patients were evaluated using MRI. Three patients presented with partial merosin deficiency and 22 with total merosin deficiency. Follow-up examinations were done in 7 cases. T1- and T2-weighted images were performed in all examinations, and fluid-attenuated inversion recovery (FLAIR) was performed in 15. Enhanced images were done in 11 cases. The WM involvement was classified according to location and severity. Results: From 1991 to 2004, 32 MRI examinations were performed. Severe involvement was found in 23 patients in the frontal and temporal lobes, in 18 patients in the parietal lobes, and in 7 patients in the occipital lobes. The brain stem (n=5), cerebellum (n=6), internal capsules (n=1), and external capsules (n=5) were also affected. One patient had occipital pachygyria, and one had cerebellar vermian hypoplasia. No gadolinium enhancement was noted. Follow-up MRI showed no interval change (n=4), progression (n=1), or improvement of the findings (n=2). Conclusion: This series of patients demonstrated that there was no correlation between the extent of WM abnormality on MRI and the clinical status and degree of merosin deficiency (partial or total). Bilateral WM involvement was seen to be more prominent in the parietal, frontal, and temporal regions of the brain. The brain stem and internal and external capsules were less affected. Cerebellar WM involvement is rare. Changes on follow-up imaging studies did not correlate with the clinical status of the patient.     

An unusual case of congenital muscular dystrophy with normal serum CK level, external ophtalmoplegia, and white matter changes on brain MRI

We report a sporadic case of congenital muscular dystrophy (CMD) in a 13-year-old girl with early manifestation of muscle weakness and hypotonia, severe contractures, bulbar syndrome, progressive external ophtalmoplegia, and white matter changes on magnetic resonance imaging (MRI) of the brain, but no mental defect. Serum creatine kinase (CK) level was normal. Muscle biopsy revealed a dystrophic picture with a prominent inflammatory infiltrate mimicking inflammatory myopathy-typical histological findings in CMD. Immunostaining showed normal expression of merosin, alpha and beta-dystroglycans. Mutation analyses of calpain3, dysferlin, and SEPN1 genes were negative. An electron microscopy revealed the accumulation of abnormally enlarged mitochondria located under the sarcolemma. Measurement of respiratory chain enzyme activities did not reveal any biochemical defect and mitochondrial genetic studies, including sequencing of the entire mitochondrial genome, were unremarkable. Phenotypic presentation of our patient is very unusual and differs considerably from other CMD variants.     

Lethal Congenital Muscular Dystrophy with Arthrogryposis Multiplex Congenita: Three New Cases and Review of the Literature

Congenital muscular dystrophy (CMD) comprises a heterogeneous group of muscle disorders. We report on two stillborn sibs with early lethal CMD and a prematurely born boy who died within minutes after birth. The pregnancies were complicated by polyhydramnios. All presented with arthrogryposis multiplex congenita, severe muscle wasting, lung hypoplasia, and hydrops. The muscle biopsies showed fibrosis, variation in fiber size, and extensive fat replacement compatible with muscular dystrophy. Fatal CMD seems to be distinct from CMD with survival after birth and is probably autosomal recessively inherited.     

Congenital muscular dystrophy with laminin α2 chain deficiency: Identification of a new intermediate phenotype and correlation of clinical findings to muscle immunohistochemistry

The laminins comprise of a family of heterotrimeric proteins of the extracellular matrix. The cross-shaped proteins consist of a heavy α-chain and two light chains, called β and γ. Each group of chains, classified on their sequence identity and domain organization, include different isoforms. A deficiency of the α2 chain of laminin-2, previously termed merosin or M component, was shown to be responsible for one form of congenital muscular dystrophy (CMD). We investigated muscle biopsies of 20 patients with the clinical diagnosis of CMD and histological evidence of muscular dystrophy for the expression of different laminin chains. Patients with evidence of pachygyria/lissencephaly of the CNS were excluded from this series. The immunohistochemical analysis was correlated to clinical findings and MRI data of the brain. Of 20 patients, 11 (55%) revealed complete or near-complete deficiency of the α2 chain in their skeletal muscle specimens. So far none of these patients became ambulant. Of 20 patients 2 showed partial but clear-cut α2 chain-deficiency. These two patients became ambulant at 18 months and 3 years. All 13 patients with complete or partial α2 chain-deficiency demonstrated cerebral white matter changes on MRI. In contrast, 6/7 CMD patients with normal α2 chain expression became ambulant and none of the 6/7 tested showed evidence of cerebral abnormal T2 sequence signal of the myelin on MRI.     

Familial leukoencephalopathy with slowly progressive dystonia and ataxia

We describe two siblings with childhood onset, slowly progressive generalized dystonia and cerebellar signs. Brain neuroimaging revealed white matter abnormalities compatible with a neuronal degenerative disorder. An extensive evaluation for mitochondrial, metabolic, autoimmune or other known neurodegenerative disorders did not reveal the etiology of the disease. During a three-year follow-up other neurological signs appeared, but progression was very slow.We believe that our patients have a new type of a leukoencephalopathy with slowly progressive dystonia and cerebellar signs.     

Sternohyoid muscle fatigue properties of dy/dy dystrophic mice,an animal model of merosin-deficient congenital muscular dystrophy

Humans with merosin-deficient congenital muscular dystrophy have both sucking problems during infancy and sleep-disordered breathing during childhood. We hypothesized that merosin-deficient pharyngeal muscles fatigue faster than normal muscles. This was tested in vitro using sternohyoid muscle from an animal model of this disease, the dy/dy dystrophic mouse. Isometric twitch contraction and half-relaxation times were similar for dy/dy and normal sternohyoid. However, rate of force loss during repetitive 25-Hz train stimulation was markedly diminished in dystrophic compared with normal sternohyoid muscle. Furthermore, force potentiation, which occurred during the early portion of the fatigue-inducing stimulation, had a longer duration in dystrophic compared with normal muscle (approximately 60 versus 20 s). As a result of these two processes, at the end of 2 min of stimulation, force of dystrophic muscle had decreased by 8 +/- 5% and that of normal muscle by 69 +/- 4% (p < 0.0001). The potassium-channel blocker, 3,4-diaminopyridine, increased force of dy/dy sternohyoid muscle during twitch and 25-Hz contractions by 148 +/- 20% (p < 0.00001) and 109 +/- 18% (p < 0.00002), respectively. During repetitive 25-Hz stimulation, force of 3,4-diaminopyridine-treated dystrophic muscle remained significantly higher than that of untreated muscle, despite the early force potentiation being eliminated and fatigue being accelerated. Thus, merosin deficiency reduces fatigue and prolongs the duration of force potentiation. The latter alterations may partially preserve the integrity of upper airway muscle function, without which the severity of pharyngeal complications (feeding problems, sleep-related respiratory dysfunction) might be even more pronounced in the human merosin-deficient congenital muscular dystrophies.     

Distinguishing Cardiac Features of a Novel Form of Congenital Muscular Dystrophy (Salih CMD)

The cardiac features of a novel form of congenital muscular dystrophy (Salih CMD) are described in two adolescent siblings. The patients presented with severe hypotonia at birth, associated with delayed development. They could walk independently and managed to maintain walking after 13 years of age. Their muscle immunohistochemistry differed from that seen in Duchenne and Becher muscular dystrophy (DMD and BMD), severe childhood autosomal recessive muscular dystrophy (SCARMD) due to sarcoglycan deficiency (sarcoglycanopathies), and lamininα2 (merosin)-deficient CMD. However, both patients had associated cardiomyopathy. Electrocardiography (ECG) in Salih CMD was characterized by delayed atrioventricular (AV) conduction, left anterior fascicular block (left axis deviation), and left atrial enlargement without evidence of atrial dysarrhythmia. Echocardiography showed features of severe left ventricular dysfunction with estimated left ventricle ejection fraction (LVEF) of 25% at 16 years-of-age in the older patient. A year later, multigated aquisition MUGA scan showed LVEF of 21% and dilatation of the right ventricle. Echocardiography and MUGA scan were normal in the younger patient at 15 years-of-age. ECG, echocardiography, and MUGA scan are effective techniques for diagnosing and monitoring the cardiomyopathy in Salih CMD. They can also distinguish it from features seen in the other common forms of MD, including DMD, BMD, and sarcoglycanopathies.     

MR imaging of pelvic and thigh muscles in congenital muscular dystrophy

To define and compare the magnetic resonance (MR) imaging findings of pelvic and thigh muscles in merosin-deficient and merosin-positive congenital muscular dystrophy, 10 patients with merosin-positive and six patients with merosin-deficient muscular dystrophy were examined in a 0.5 T MR imaging unit. Intensity and atrophy scores were given to individual muscles by two radiologists and were calculated for three muscle groups (pelvic, anterior thigh and posterior thigh muscles). Rectus femoris was affected less than the vastus muscles in 40 percent of cases in merosin-positive patients, whereas there was no selective sparing in merosin-deficient patients. Sartorius and gracilis were relatively spared in both groups. The most consistently affected muscles were gluteus maximus, adductor magnus and brevis in merosin-positive patients. Atrophy was more prominent in the adductor muscles in the merosin-deficient group. Intensity scores of anterior thigh muscles of the merosin-positive group were significantly higher than those of the merosin-deficient group (U = 8, p = 0.016). When stepwise logistic regression model was applied, intensity score of the anterior thigh muscles was found to be the best differentiating variable. The regression analysis model formed was able to differentiate the two forms with a sensitivity of 80 percent and specificity of 83 percent.     

Guillain-Barré syndrome associated with central nervous system lesions

We report the clinical course, and neurophysiological and neuroimaging findings of a patient with Guillain-Barré syndrome associated with central nervous system lesions. During a course of intravenous immunoglobulin therapy, she had headache with meningism. Cerebral magnetic resonance imaging showed lesions in both frontal and right occipital lobes. Cerebrospinal fluid showed a raised protein concentration accompanied by mild pleocytosis. Her symptoms resolved within two months. Subsequent magnetic resonance imaging revealed cavity formation in the deep white matter and atrophic changes in the right occipital lobes.     

Congenital Muscular Dystrophies -Problems of Classification

The classification of congenital muscular dystrophies (CMD), based on perceived clinical and morphological similarities or differences, is controversial. CMD without cerebral involvement has sometimes been divided into a mild and a severe form. This distinction is, however, arbitrary and not uncontested. Whether Ullrich's disease, formerly called atonic-sclerotic dystrophy, is a disease entity and if so, whether it is a primary muscle disorder, is uncertain. CMD without cerebral involvement is inherited in an autosomal recessive fashion in the great majority of cases. CMDs with cerebral involvement are usually classified into at least three forms: the Fukuyama type of CMD, occurring almost exclusively in Japanese patients; CMD with hypomyelination, sometimes also called the occidental type of cerebromuscular dystrophy; and Walker-Warburg syndrome. Muscle-eye-brain disease, described in a number of Finnish patients, may or may not belong in this last category. In CMD with cerebral involvement inheritance is also autosomal recessive. It is possible that single sporadic cases are pheno-copies due to infectious or other exogenous causes. Reports of clinical and morphological findings from an increasing number of patients show a high degree of variability within and, on the other hand, certain similarities between the forms of CMD with cerebral involvement. In addition, neuroradiological changes are also found with increasing frequency in CMD patients without clinical neuropsychological abnormalities. It is not unreasonable to speculate that molecular genetic techniques will reveal in the near future a variable defect in one gene locus or defects in a few gene loci as the cause of the various clinical forms of CMDs.     

Guillain-Barré syndrome associated with central nervous system lesions.

We report the clinical course, and neurophysiological and neuroimaging findings of a patient with Guillain-Barré syndrome associated with central nervous system lesions. During a course of intravenous immunoglobulin therapy, she had headache with meningism. Cerebral magnetic resonance imaging showed lesions in both frontal and right occipital lobes. Cerebrospinal fluid showed a raised protein concentration accompanied by mild pleocytosis. Her symptoms resolved within two months. Subsequent magnetic resonance imaging revealed cavity formation in the deep white matter and atrophic changes in the right occipital lobes.     

Congenital muscular dystrophy with laminin-a2 deficiency in early infancy: diagnosis and long-term follow-up

Congenital muscular dystrophy (CMD) is a heterogeneous group of neuromuscular disorders characterized by muscle weakness and hypotonia at birth or within the first few months of life. It is inherited in an autosomal recessive pattern. About half of the patients have a deficiency of the alpha-2-chain of laminin (merosin). We describe a case of congenital muscular dystrophy in an infant with laminin-a2-chain deficiency, which appeared hypotonia in early infancy. Diagnosis was made by clinical features and the histological and immunohistochemical studies on muscle biopsy.     

Contralateral hemimicrencephaly in neonatal hemimegalencephaly

Identification of abnormalities in the contralateral hemisphere in patients with hemimegalencephaly is critical in their management. In this report, we present a 5-day-old neonate with hemimegalencephaly who demonstrated an enlarged ipsilateral cerebral hemisphere and diffuse volume loss in the contralateral hemisphere on conventional MR imaging sequences. The ipsilateral frontal white matter demonstrated relatively increased NAA, fractional anistropy, and cerebral blood volume values compared to published normative data. In addition, the white matter of the contralateral hemisphere demonstrated elevated lactate and increased mean diffusivity compared to published normative data, supporting the abnormal conventional MR findings. Advanced MR neuroimaging techniques may help further confirm and characterize abnormalities in the smaller contralateral hemisphere in neonatal hemimegalencephaly.     

MRI in children with mental retardation

BACKGROUND: In mental retardation (MR) an aetiological diagnosis is not always obtained despite a detailed history, physical examination and metabolic or genetic investigations. In some of these patients, MRI is recommended and may identify subtle abnormal brain findings. OBJECTIVE: We reviewed the cerebral MRI of children with non-specific mental retardation in an attempt to establish a neuroanatomical picture of this disorder. MATERIALS AND METHODS: Thirty children with non-specific MR were selected to undergo cerebral MRI. The examination included supratentorial axial slices, mid-sagittal images and posterior fossa coronal images. Brain malformations, midline and cerebellar abnormalities were studied. RESULTS: In 27 of 30 patients, the neuroimaging evaluation revealed a relatively high incidence of cerebral and posterior fossa abnormalities. The most frequent were: dysplasia of the corpus callosum (46%; hypoplasia, short corpus callosum and vertical splenium), partially opened septum pellucidum and/or cavum vergae (33%), ventriculomegaly (33%), cerebral cortical dysplasia (23%), subarachnoid space enlargement (16.6%), vermian hypoplasia (33%), cerebellar and/or vermian disorganised folia (20%), and subarachnoid spaces enlargement in the posterior fossa (20%). Other anomalies were: enlarged Virchow-Robin spaces (10%), white matter anomalies (10%) and cerebellar or vermian atrophy. CONCLUSIONS: MRI has shown a high incidence of subtle cerebral abnormalities and unexpected minor forms of cerebellar cortical dysplasia. Even if most of these abnormalities are considered as subtle markers of brain dysgenesis, their role in the pathogenesis of mental retardation needs further investigation.     

Infantile-onset megalencephalic leucoencephalopathy in two siblings

Infantile-onset megalencephalic leucoencephalopathy (IML) is a recently recognized autosomal recessive white matter disorder. Unlike other megalencephalic leucoencephalopathies, in patients with IML a mild clinical course, a slowly progressive delay in motor development and mild mental deterioration are typical. We report on two affected siblings who have typical clinical and radiological findings of IML. Cranial magnetic resonance imaging showed involvement of the capsula externa, extrema and interna, nucleus dentatus, crus cerebri, periventricular and subcortical white matter. In addition, bilateral cystic changes were determined predominantly in the temporal lobes. There were no clear biochemical or metabolic disturbances. In the present paper, we discuss the clinical and neuroimaging findings of IML.     

The congenital muscular dystrophies: recent advances and molecular insights.

Over the past decade, molecular understanding of the congenital muscular dystrophies (CMDs) has greatly expanded. The diseases can be classified into 3 major groups based on the affected genes and the location of their expressed protein: abnormalities of extracellular matrix proteins (LAMA2, COL6A1, COL6A2, COL6A3), abnormalities of membrane receptors for the extracellular matrix (fukutin, POMGnT1, POMT1, POMT2, FKRP, LARGE, and ITGA7), and abnormal endoplasmic reticulum protein (SEPN1). The diseases begin in the perinatal period or shortly thereafter. A specific diagnosis can be challenging because the muscle pathology is usually not distinctive. Immunostaining of muscle using a battery of antibodies can help define a disorder that will need confirmation by gene testing. In muscle diseases with overlapping pathological features, such as CMD, careful attention to the clinical clues (e.g., family history, central nervous system features) can help guide the battery of immunostains necessary to target an unequivocal diagnosis.