Medical records of 32 patients with cryptogenic West syndrome were reviewed for factors correlating with developmental outcome in a study at Saitama Children’s Medical Center, and the Jikei University School of Medicine, Tokyo, Japan. Clinical features were compared in a normal outcome group of 12 patients and a delayed outcome group of 20 patients. In the delayed outcome group, 5 patients had mild mental retardation (IQ, DQ 50-75), 8 were moderately retarded (IQ 25-50), and 7 were severely retarded (IQ <25). Age at onset of spasms and duration of follow-up were the same in the delayed and normal (IQ >75) outcome groups. The retarded group compared to the normal outcome group differed in the longer time from seizure onset to initiation of treatment (mean, 104.5 vs 40.8 days, P<0.05), and a longer time from onset to cessation of spasms (mean, 139.8 vs 77.0 days, NS). ACTH controlled spasms for > 28 days and hypsarrhythmia was resolved in all 32 patients initially (spasms disappeared after exanthem subitum in one patient without treatment). The duration from beginning ACTH to control of spasms was the same in both delayed and normal outcome groups (mean, 3.6 vs 2.8 days, NS). Relapse of spasms occurred in 7 of 20 delayed outcome patients (average time 2.8 +/- 1.6 months) and in none of the normal group (P<0.05). Other types of seizures (focal motor, complex partial, generalized) occurred in 11 of the delayed outcome group, evolving to focal epilepsy in 7. Paroxysmal EEG discharges did not reappear in 8 of the normal and 3 of the delayed outcome groups (P<0.05). Reappearance of EEG paroxysms occurred in 4 of the normal and 17 of delayed outcome groups; Average age of reappearance of EEG paroxysms was later in the delayed cf normal outcome groups (29.2 vs 10.8 months, P<0.05). Frontal and parieto-occipital regions were the most common locations for reappearance of paroxysmal discharges in the delayed outcome group. 
COMMENT. The importance of early diagnosis and treatment of infantile spasms, demonstrated by this study, confirms previous reports of a correlation of improved response and prompt initiation of ACTH therapy (Millichap JG, Bickford RG. JAMA 1962; 182:523-527). Of 21 patients referred to the Mayo Clinic, 80% of infants diagnosed and treated at < 1 year of age were benefited whereas only 22% older than 1 year at diagnosis showed reduction in spasms and EEG improvement. The shorter the treatment lag, the more favorable the outcome. 
In the above study, patients with a poor outcome have a greater risk of focal epilepsy and persistent paroxysmal EEG discharges in frontal regions. In a long-term study of 214 patients followed for 20-35 years at the University of Helsinki, Finland , factors predictive of a good prognosis included cryptogenic etiology, normal development before onset of spasms, and a good response to ACTH. Focal abnormalities in the EEG were not necessarily indicative of a poor prognosis.