[Tolerance and plasticity against the intracranial pressure in cases of chronic subdural hematoma in the aged brain].

A consecutive series of 94 patients with chronic subdural hematomas (CSDHs) was studied on compensation against intracranial pressure and tolerance, and plasticity from compression of CSDHs, comparing between 47 cases of the aged group over 70 years of age and 47 cases of the younger group under 69 years of age. Better compensation from compression of CSDHs in the aged group was demonstrated from the fact those of long duration from impact to onset of symptoms, few cases with signs of chronic intracranial hypertension and volume of hematoma over 100 ml. But, when CSDHs progressed over 100 ml in size, this compensation mechanism and also tolerance against increased intracranial pressure were deprived. Disturbance of consciousness and anisocoria were shown much more in the aged group on admission. Patients in the aged group demonstrated reduced brain reexpansion and poor clinical recovery during 3 months after surgery. CT performed on 3 months after surgery demonstrated persisting subdural fluid in 63% of cases in the aged group comparing with 8% of those in the younger group. There was significant difference about morbidity between two groups. These study suggests that the plasticity and elastance in the aged brain reduce because of brain atrophy and impairment of cerebral blood flow, then brain reexpansion and clinical improvement may participate in delay regardless of release from compression of CSDHs. It may be urged that the critical age maintaining the plasticity of the brain in cases with SDHs in 75 years of age.