SURGICAL OPTIONS IN THE TREATMENT OF INTERHEMISPHERIC ARACHNOID CYSTS

BACKGROUND Arachnoid cysts located within the interhemispheric fissure are a matter of discussion as to the surgical indication and the choi ce of the most appropriate surgical procedure. In fact, in spite of th e large dimensions that they can reach, the clinical manifestations ma y remain subtle and apparently stable over the years. On the other han d, the larger utilization of prenatal ultrasound investigations has in creased the number of lesions detected before they can provoke clinica l manifestations. As far as surgery is concerned, two main options are available-an extrathecal shunting procedure or a direct approach to t he lesion, with excision of its wall. METHODS In this report, we analy ze the results obtained in 25 children harboring an interhemispheric a rachnoid cyst, surgically treated in the period 1978 to 1994. Mean age at diagnosis was 18.8 months (10 days to 15 years). RESULTS The main clinical manifestations included macrocrania, mild to moderate signs o f increased intracranial pressure, cranial bulging, developmental dela y, and neurologic signs. In 14 cases, the diagnosis had been obtained prenatally, The cyst was located in one hemicranium in 16 cases, where as it was on the midline, with bilateral extension, in the remaining 9 cases; in the latter cases, variable degrees of callosal agenesis wer e also observed, All 25 children were operated on. In 16 of them, the treatment consisted of a craniotomy with wide excision of the cyst lin ing and marsupialization into the subarachnoid spaces of the midline ( and/or into the ventricular system). In 6 children, tile surgical proc edure was a cystoperitoneal (CP) shunt. The last 3 children of our ser ies underwent craniotomy and cyst excision after having been treated b y means of a ventriculoperitoneal shunt. At follow-up examination, 17 children are normal, and the remaining 8 disclose mild to moderate psy chomotor retardation CONCLUSIONS Although both craniotomy and CP shunt are associated with good results, the first surgical procedure offers the advantage of avoiding the insertion of a permanent cerebrospinal fluid shunt device and the known complications of this type of procedu re.