The number, size and distribution of cerebral hamartomas determined by MRI in 11 patients with tuberous sclerosis and normal intellect are reported from the Bath Unit for Research into Paediatrics, Royal United Hospital, Combe Park, Bath, Avon, England and Bristol MRI Centre, Frenchay Hospital, Bristol. Nine patients had between 2 and 9 cerebral tubers seen on MRI T2 weighted images, 7 had 1-5 subependymal nodules and 2 had normal scans. The hamartomas were at least 4 mm in size. The number of lesions found on the MRI may not be used to predict neurological outcome in tuberous sclerosis. Only 3 of the 11 patients had a history of seizures and all had normal intellect. 
COMMENT. The authors suggest that the wrong conclusions may be drawn if the number of lesions alone on cranial MRI is used to predict neurological outcome in tuberous sclerosis. Lesions seen on both MRI and CT may become less obvious with advancing age in patients with tuberous sclerosis. In the experience of these authors, individuals who reach 5 years of age with normal development do not develop mental handicap from tuberous sclerosis. While the number of cerebral hamartomas appears to be an unreliable predictor of clinical outcome it is possible that the distribution and size of lesions may be more helpful. Patients with temporal lobe or occipital lobe hamartomas are most likely to have seizures or EEG abnormalities. Tuberous sclerosis was the cause of infantile spasms in 10% of cases treated in Finland (see Ped Neurol Briefs April 1990) but in only 2% reported from China.