Journal (f the Neurological Sciences, 105 (1991) 1-5 ~c) 1991 Elsevier Science Publishers B.V. All rights reserved 0022-510X/91/$03.50 JNS 03603 Cardiomyopathy, mental retardation, and autophagic vacuolar myopathy Abnormal MRI findings in the head Nobuyuki Kashio 1"2, Fusako Usuki 2, Toshihiko Akamine 1, Susumu Nakagawa 3, Itsuro Higuchi 2, Keiichi Nakahara 2, Akihiko Okada 4, Mitsuhiro Osame 2 and Fusayoshi Murata 5 J Departments ~ Neurology, and 31nternalMedicine. Miyazaki Prefectural Hospital, Miyazaki 880 (Japan). 2Third Department of Internal Medicine. and 5Second Department of Anatomy, Faculty of Medicine, Kagoshima University, Kagoshima 890 (Japan). 4Department of Neurology, Fujimoto Hospital. Miyakonojo 885 (Japan) Key words: Lysosomal glycogen storage; Normal acid c~-glucosidase activity; Cardiomyopathy; Mental retardation; Muscular weakness; Magnetic resonance imaging (MRI) Summary A 21-year-old man with childhood-onset mental retardation, non-obstructive hypertrophic cardiomyopathy, and vacuolar myopathy is presented. A histopathological study ofbiopsied skeletal muscle showed lysosomal glycogen storage mimicking acid maltase deficiency, but biochemical analysis showed normal acid c~-glucosidase activity. Glycogenosomes were also recognized in endothelial cells on electronmicroscopic examination of biopsied skeletal muscle. Magnetic resonance imaging (MRI) findings in the head revealed the involvement of the central nervous system. This is a new type of lysosomal glycogen storage disease with multisystemic involvement. The specific biochemical defect in this disorder remains to be elucidated. Introduction Glycogenosis type II, acid maltase deficiency (AMD), is an autosomal recessive disorder characterized by the lyso- somal accumulation of glycogen due to a deficiency of a lysosomal enzyme, acid ~-glucosidase (EC 3.2.1.20) (Hers et al. 1963). The clinical spectrum of AMD comprises the infantile and late-onset types (subdivided into the childhood and adult types). The infantile type is a gen- eralized glycogen storage disease characterized by muscu- lar hypotonia and weakness, hepatomegaly, cardio- myopathy and dysfunctioning of the central nervous sys- tem. In contrast, the clinical manifestations in the late-onset types are mainly limited to skeletal muscle. In 1981, however, Danon et al. (1981) reported two unrelated patients whose biopsied skeletal muscle showed lysosomal glycogen storage resembling AMD, but the acid ~-glucosidase activity was normal. The clinical manifes- tations were childhood-onset mental retardation, hyper- trophic cardiomyopathy and proximal myopathy. This dis- tribution of the involved organs was different from that seen in the late-onset type of AMD, in which myopathy was the Correspondence to: Dr. Nobuyuki Kashio, Third Department of Inter- nal Medicine, Faculty of Medicine, Kagoshima University, Sakuragaoka 8-35-1, Kagoshima 890, Japan. Tel.: 0992-64-2211 (ext. 2065); fax: 0992-65-9721. main manifestation. There are some reports of a similar syndrome later (Riggs et al. 1983; Byrne et al. 1986; Hart et al. 1987; Tachi et al. 1989). In this paper, we present a new non-familial case, whose MRI findings in the head revealed the involvement of the central nervous system. Detailed electron-microscopical examination of biopsied muscle was performed. Case report A 21-year-old man was admitted with the chief complaints of fatigability and generalized muscle weakness. He had a normal birth after an uneventful pregnancy. No abnormalities had been noted until he attended classes for the mentally retarded at age 11. He became a slow runner in a short distance race. At age 14, he sometimes experienced episodes of palpitations. At age 16, a chest radiograph showed cardiomegaly. He underwent a cardiac evaluation. Cardiological studies, including cardiac catheterization, showed "hypertrophic non-obstructive cardio- myopathy", and so he was treated with atenolol and verapamil. He was the first of three children. Both his sisters and both parents, who were unrelated, were normal. There was no family history of neuromuscular or cardiac diseases. On physical examination at age 21, he appeared slender without dysmorphic features. There was no edema or cyanosis. A grade II systolic murmur was heard at the left lower sternal border. The liver and spleen were not enlarged. Pigmental degen- eration was found on ophthalmoscopy, but cherry red spots were