Role of computerized axial tomography in diagnosis, treatment and follow-up of hydrocephalus. Preliminary communication

Reversible porencephaly. Alteration of the cerebrospinal fluid flow after shunt malfunction

The cases of four infants (five lesions) are reported, where "porencephalic cysts," located along the ventricular catheter after shunt malfunction and Ommaya reservoir insertion, disappeared after ventriculoperitoneal (VP) shunt revision and combined cyst peritoneal (CP) shunt, or after VP shunt alone. This pathological state is thought to be a rare postoperative complication. Its pathogenesis and therapy are discussed. Shunt malfunction or Ommaya reservoir insertion may result in a hypertensive hydrocephalic state. Cerebrospinal fluid (CSF) flows out through a catheter penetrating the site of the ventricular wall and expands in the surrounding white matter to form a porencephalic cavity. Once this porencephalic state occurs, it will not disappear spontaneously because the CSF flows in one direction. As treatment for closed porencephaly, CP shunt following a VP shunt revision was markedly effective; for communicating porencephaly, a VP shunt revision alone was effective.

Ventricular shunt functioning despite extraventricular location of the catheter tip as revealed by computed tomography

Two cases of infantile hydrocephalus are reported, in which the ventricular shunt proved to function despite the catheter tip being located outside the ventricular system, as revealed by computed tomography. This condition could be erroneously diagnosed as arrested hydrocephalus or proximal shunt malfunction, with a resultant potential risk of inadequately removing the catheter.

Subdural effusions re-appearing after shunts in patients with non-tumoural stenosis of the aqueduct

Three patients shunted for non-tumoural stenosis of the aqueduct suffered from progressive clinical symptoms about four months after the shunting. Computed tomography (CT) showed bilateral subdural effusions. The effusions were evacuated, and the shunts revised. One month later all patients suffered from symptoms of increased intracranial pressure, and CT showed enlargement of the supratentorial cerebral ventricles. The effusions had disappeared. After shunt revision the symptoms decreased again. The fluctuation in the ventricular size, the thickness of the subdural effusions, and the clinical deterioration were related to the change in the opening pressure of the shunt valve in all patients. Patients with large supratentorial cerebral ventricles (Evans index over 0.40) should be monitored by intraventricular pressure recording in order to select the exact opening pressure of the shunt valve before inserting a relieving shunt; a clinical check-up and a CT examination should be carried out about three months after the operation in order to investigate any changes in the function of the shunt.

Ventriculo-subgaleal shunt: evaluation by computed tomography

Ventriculo-subgaleal shunting was used for temporary decompression of hypertensive hydrocephalus. Pre- and post-shunt computed tomography was utilized in five cases as a method for detecting complications and determining shunt function. A clear-cut clinical improvement and stabilization followed the subgaleal diversion, but nevertheless usually only a mild decrease in ventricular size was demonstrated after shunting.