Strokes related to intracranial aneurysm or arteriopathy have been reported in a few patients with late-onset Pompe disease. These reports suggested that cerebral vessels involvement could represent an under recognised complication of this disease. We report three French patients with late-onset Pompe disease and cerebral arteries involvement. Patient 1, was a 35-year-old woman who presented subacute headaches revealing a giant fusiform aneurysm of basilar artery. She subsequently developed intracranial hypertension and died suddenly 10 days after a surgical inter- vention for ventriculo-peritoneal derivation. Patient 2, aged 34 years, is the sister of patient 1. A Brain MRI performed at age 30 years showed a dolichoectasia predominating in the vertebro-basilar circulation, but she had no neurological symptoms. Patient 3 is a 50-year-old man who has been admitted in intensive care unit at 44 years of age, for a coma pre- ceded by subacute headaches. Brain MRI showed cerebellar oedema with triventricular hydrocephalus, and cerebral arteriography revealed dilatative arteriopathy. The patient recovered spontaneously without neurological sequel. All patients also presented muscular weakness with pelvic-girdle weakness and respiratory involvement necessitating mechan- ical ventilation. Patients 2 and 3 are currently treated with enzyme replace- ment therapy (Myozyme) since 2 years and 6 months, respectively. Regular angiographic follow-up showed the absence of progression of vascular abnormalities in patient 2. In conclusion, Pompe disease should be recognized as a predisposing condition to dilatative arteriopathy and cerebral aneurysm formation, although the real incidence of these vascular complications remains unknown. Enzyme replacement therapy could be the first opportunity to stabilize or reverse these potentially fatal cerebral vessels complications. However, a more prolonged course of treatment is necessary before establishing firm conclusions in our patients. doi:10.1016/j.nmd.2007.06.116 M.P.2.08 Cardiologic evaluation in adults with Pompe disease shows no signs of cardiomyopathy Van der Beek, N. 1,* ; Soliman, O. 2 ; Geleijnse, M. 2 ; Kroos, M. 3 ; Reuser, A. 3 ; Vletter, W. 2 ; van der Ploeg, A. 4 ; Van Doorn, P. 1 1 Erasmus MC, Neurology, Rotterdam, The Netherlands; 2 Erasmus MC, Cardiology, Thoraxcenter, Rotterdam, The Netherlands; 3 Erasmus MC, Clinical Genetics, Rotterdam, The Netherlands; 4 Erasmus MC – Sophia, Pediatrics, Division of Metabolic Diseases, Rotterdam, The Netherlands Pompe disease is an inherited metabolic disorder caused by deficiency of acid a-glucosidase, an indispensable enzyme for the breakdown of lyso- somal glycogen. The classic-infantile form of Pompe disease is character- ized by hypotonia, poor motor development and cardiorespiratory failure, resulting in death within the first year of life. Massive left ventricular hypertrophy and pre-excitation on ECG is well known in patients with this phenotype. Patients with milder phenotypes usually present in the first to sixth decade of life with a slowly progressive proximal myopathy or, occa- sionally, with pulmonary distress. It is not known to what extent cardiac involvement is a feature in these milder phenotypes, and if cardiac evalu- ation should be applied in routine examination of adult patients. Cardiac function was evaluated in 52 adults with Pompe disease through electro- cardiography and echocardiography as part of a large prospective study on the natural course of late-onset Pompe disease. The mean age of the patients was 47 years (range 25 to 72 years). The clinical spectrum varied from mildly affected to severely affected patients who were wheelchair dependent and required artificial ventilation for 24 h a day. Six patients presented with onset of symptoms in childhood or adolescence, one patient even in the first year of life. Cardiologic evaluation did not reveal major abnormalities in any of the patients. One patient had a short PR- interval, and three others had conduction disturbances in the bundle branches. Echocardiography showed signs of left ventricular hypertrophy in one patient. The prevalence of these abnormalities was not higher than in the general population. In a group of 52 adults with Pompe disease detailed cardiologic evaluation did not reveal signs of cardiac involvement, not even in patients with early onset of symptoms or a long disease history nor in severely affected patients. We conclude that routine cardiologic screening is not needed in adults with Pompe disease. doi:10.1016/j.nmd.2007.06.117 M.P.2.09 The utility of skeletal muscle CT scan in childhood-onset Pompe disease Ishigaki, K. 1,* ; Murakami, T. 1 ; Shishikura, K. 1 ; Suzuki, H. 1 ; Hirayama, Y. 1 ; Arai, Y. 1 ; Sugie, H. 2 ; Osawa, M. 1 1 Tokyo Women’s Medical University, School of Medicine, Department of Pediatrics, Tokyo, Japan; 2 Hamamatsu City Medical Center for Devel- opmental Medicine, Department of Pediatric Neurology, Hamamatsu, Japan The characteristic skeletal muscle patterns on CT scan in adult-onset Pompe disease patients were reported to be atrophic or moth-eaten changes in trunk muscles and the vastus muscle of the thigh. However, no report has summarized muscle CT findings in childhood-onset type Pompe disease. We previously reported one particularly striking case of childhood Pompe disease with high image density of severely affected mus- cles on CT. To confirm the characteristic skeletal muscle changes seen on CT scan in patients with childhood-onset Pompe disease. Two patients with childhood-onset Pompe disease were evaluated. The first was a 13- year-old boy, the second a 5-year-old boy. Muscle CT scan was performed at seven levels. Muscle changes on CT scan of the first patient were assessed at the ages of 13, 22 and 29 years. Both patients specifically showed high image density in the rectus muscle of the thigh and tibial mus- cles. Not only increased density, but also the distribution of affected mus- cles apparently differed from the patterns seen in adult-onset type Pompe disease. The high image density distribution was consistent with a marbled pattern involving the bulk of each muscle, and this feature became more striking with progression of the disease. High image density on muscle CT scan is a characteristic change of child-onset Pompe disease. We rec- ommend muscle CT scan for differential diagnosis and for assessing dis- ease progression. doi:10.1016/j.nmd.2007.06.118 M.P.2.10 Disease methods: Development of a simple mechanism to calculate disease severity in Pompe patients Giannini, E. 1 ; Marsden, D. 2,* ; Berger, K. 3 ; van der Ploeg, A. 4 ; Case, L. 5 ; Dandrea, C. 2 1 Cincinatti Children’s Hospital, Cincinatti, United States; 2 Genzyme, Cambridge, United States; 3 New York University, NY, United States; 4 Erasmus/Sophia Children’s Hospital, Rotterdam, The Nether- lands; 5 Duke University Medical Center, Durham, United States Background: A Disease Severity Scoring System (DS3) is a method to measure disease burden in patients, consisting of critical health domains, each described by relevant clinical assessment(s) quantified by reliable, fea- sible methods. DS3 is particularly useful in rare, heterogeneous diseases in which evaluating severity and prognosis are complex. Properly configured, a DS3 provides inter- and intra-patient comparisons through time across critical organ systems. A DS3 development is underway for Pompe disease, a rare, autosomal recessive, heterogenous and debilitating neuromuscular disorder due to a deficiency of the lysosomal enzyme acid-a-glucosidase resulting in glycogen accumulation in cardiac, skeletal and/or pulmonary muscle. Methods: A panel of Pompe experts was assem- bled in 2006 to identify critical Pompe disease health domains. A broader ‘‘Delphi’’ physician group was then consulted to capture gold standard medical practice(s) for severity measurement within each critical health Abstracts / Neuromuscular Disorders 17 (2007) 764–900 795