Retrospective Survey of Urea Cycle Disorders: Part 2. Neurological Outcome in Forty-nine Japanese Patients with Urea Cycle Enzymopathies

We analyzed neurological data, including DQ or IQ, EEG, and CT scan, in 49 patients with urea cycle enzymopathies, all of whom were included in a retrospective survey from 1978-1988 in Japan. We classified 3 groups depending on age-at-onset: group 1 (0-28 days, N = 11), group 2 (29 days-5 years, N = 31), and group 3 (greater than 5 years, N = 7). The least DQ or IQ score and the highest CT score, representing the most severe brain damage was found in group 1, and the highest DQ or IQ and the least CT score was found in group 3. Intermediate scores of both parameters were found in group 2. There was a negative correlation between these 2 parameters (r = -0.82, P less than 0.01). Abnormal EEG during the attack-free period was predominantly observed in patients with CT abnormalities compared to those with a normal CT scan (P less than 0.01). Approximately 40% of the patients, mostly in groups 2 and 3 (92.8%) had normal findings in all 3 parameters. Thus, the magnitude of developmental abnormalities is clearly related to the degree of brain damage and to the age-at-onset of these diseases.