Although the shunt for arachnoid cyst can get the more rapid good radiological outcome, the shunt-related complication and dependency would be hazardous. We suggest that endoscopic or reduced open procedures offer the advantage of avoiding a large craniotomy or the known complications of a cystoperitoneal shunt in treatment of arachnoid cysts. We could get the nearly same surgical outcome without shunt complications with endoscopic or open procedures.

For clarifying the pathophysiology of arachnoid cysts and restablishing therapeutic criteria for such cases, we reviewed a series of 90 cases with arachnoid cysts focusing on the traumatic origin. Arachnoid cysts of congenital origin have been well known. But we suspected that 14 out of 90 patients (15.6%) with arachnoid cyst were closely related to head trauma. Seven of them suffered from head traumas in infancy. The episodes of head trauma included falling down in 4 patients, slipping down in 2 patients, and a motor vehicle accident in 1 patient. Traumatic arachnoid cysts had a latent period from head trauma to initial clinical manifestation. The mean latent period was 2.2 years, ranging from 10 months to 6.2 years. Six of 7 arachnoid cysts were located in the suprasellar area and 1 at the posterior fossa. An other 7 patients had a history of perinatal trauma. We postulate that head trauma in infancy may contribute to the pathogenesis of arachnoid cyst in some cases.

This investigation was undertaken to characterize CSF flow at the level of the aqueduct of Sylvius with a phase-contrast cine MR pulse sequence in 28 healthy volunteers. Sixteen patients with obstructive hydrocephalus and 11 patients with normal pressure hydrocephalus (NPH) were investigated with the same sequence before and after CSF diversion. The peak CSF flow velocity and stroke volume in the aqueduct increased significantly in the NPH group and decreased significantly in the obstructive hydrocephalus group. After lumboperitoneal shunting in the NPH group, the retrograde flow of CSF was anterogradely converted and the peak flow velocities decreased somewhat. The clinical diagnosis of NPH was well correlated with the results of cine MRI. After endoscopic III ventriculostomy in the obstructive hydrocephalus group we noted increased CSF flow velocity with markedly increased stroke volume at the prepontine cistern. Phase-contrast cine MR is useful in evaluating CSF dynamics in patients with hyperdynamic aqueductal CSF or aqueductal obstruction.

The higher ischemic risks from surgical treatment should be considered for patients with moyamoya disease who are younger than 3 years of age and have a preoperative cerebral infarction. It is also recommended that the revascularization surgery be delayed for at least 6 weeks after the development of the previous cerebral infarction.