IMAGES IN NEUROLOGY
|Year : 2006 | Volume
| Issue : 1 | Page : 49-50
Muscle - eye - brain disease
S Raghavendra, Bobby Devasia, Sanjeev V Thomas
Sree Chitra Tirunal Institute of Medical Sciences and Technology, Trivandrum - 695011, India
Sree Chitra Tirunal Institute of Medical Sciences and Technology, Trivandrum - 695011
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Raghavendra S, Devasia B, Thomas SV. Muscle - eye - brain disease. Ann Indian Acad Neurol 2006;9:49-50
A one-year-old girl, born of first-degree consanguineous parentage, presented with motor predominant global developmental delay. She had no seizures or family history of similar illness. Examination revealed a convergent squint, normal head circumference, generalized hypotonia, normal muscle bulk, and poor neck control and truncal weakness. Limb power was well preserved. Deep tendon relfexes were normal. The ophthalmic examination showed a high myopia. Serum creatine phospho kinase (CPK) was elevated at 1363 U/l. Visual evoked potentials (VEP) showed normal P100 latency. Motor nerve conduction studies and EEG were normal. Electromyography showed a myopathic pattern. Muscle biopsy showed myopathic changes with normal immunohistocytochemistry.
Cranial MRI, showed disorganized cerebellar folia, polymicrogyria and multiple subcortical cysts. [Figure - 1]A, B Cortical dysplasia was seen involving both the parieto-occipital region. [Figure - 1]C The frontal lobes sulcations were abnormal. There was abnormal diffuse symmetrical increased signal from the white matter of all the lobes including the subcortical U-fibres and the periventricular white matter. [Figure - 1]D There was marked hypoplasia of pons, inferior vermis. The midbrain colliculi were fused but corpus callosum was normal. [Figure - 1]A, E MR spectroscopy from the area of altered signals was suggestive of hypomyelination. [Figure - 1]F
| Discussion|| |
The clinical possibilities in this floppy infant with delayed milestones and raised CPK includes muscle eye brain disease (MEB), Walker-Warburg syndrome More Details (WWS) and Fukuyama type congenital muscular dystrophy (F-CMD). The extent of ocular involvement can help to distinguish them to some extent. Severe malformations, including malformation of the anterior chamber and persistent primary vitreous, are typical of WWS. Simple myopia without structural changes occurs in some FCMD patients. The characteristic ocular malformation of MEB is that of progressive myopia, as seen in this patient. The other manifestations include strabismus, congenital glaucoma, lens opacity, retinal hypoplasia or atrophy and optic atrophy. The CNS abnormalities include severe mental retardation, hydrocephalus and seizures. They can have low or isoelectric retinograms due to the retinal hypoplasia or atrophy. The VEP may be delayed but giant (>50 mV) in amplitude.
Patients with MEB have muscle weakness and hypotonia at birth or during first few months of life. Elevated CPK may occasionally be the only sign of a muscular dystrophy. Electromyography (EMG), raised CPK and muscle biopsy findings were compatible dystrophinopathy. MEB is a rare autosomal recessive disorder characterized by congenital muscular dystrophy, structural eye abnormalities, and cortical neuronal migration disorder, and type II (cobblestone) lissencephaly. Ventriculomegaly as observed in this patent or communicating hydrocephalus is due to obliteration of the subrachnoid space secondary to migration of heterotopic young neurons beyond the marginal zone (future layer I) leading to impaired absorption of the CSF.
The MRI findings of MEB disease, as seen in this patient, include cerebellar polymicrogyria with subcortical cysts, diffuse cerebral cortical dysplasia, pontine and cerebellar vermian hypoplasia and patchy hypomyelination. The cerebral cortex showed frontal pachygyria with relatively less severe gyral abnormalities in the occipital region. Other features such as callosal hypogenesis, hydrocephalus and absence of the septum pellucidum were not seen in this patient. Other MRI features also may help to distinguish between these three conditions. The cerebellum is less involved than in Walker-Warburg Syndrome, and the midline may be hypoplastic, but hemispheres are usually normal. Cerebellar polymicrogyria is associated with tiny cysts in the cerebellum. Dandy-Walker malformation and cephaloceles are not seen in MEB (these are features seen in Walker- Warburg Syndrome). Diffuse periventricular white matter changes that are observed in late infancy may decrease in severity with age. The nodular cortical migration defect is similar in MEB and FCMD; but the brain stem, which is characteristically flat in MEB, is normal in FCMD.
Clinical and MRI characteristics may help to distinguish MEB from other autosomal recessive congenital muscular dystrophies such as WWS and F CMD. Estimation of CPK in all cases of malformation of cortical development may pick up more such cases since muscular dystrophy may often be clinically subtle.
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