[Intracranial pressure. Direct measurement in the cisterna magna].

The intracranial cisternal or supraoccipital punction in the sitting position, was undertaken in 523 cases, of which 329 presented increased intracranial pressure. The procedure must be done by experts, and was well tolerated. There were no cases of death, arterial hemorrhages or medullary lesions. In 451 cases CSF pressure was measured and CSF was extracted for laboratory examination. Pneumoencephalograms were undertaken with this method in 335 patients. The intracranial cisternal pressure in the sitting position is greater than the suboccipital or cervical cisternal pressure by 1.5 to 3cm H2O. Its value is practically equal to the pressure in the posterior fossa, and when the medial ventricular system is patent, is similar to the pressure in the supratentorial fossas. The intracranial cisternal punction has less risks than the suboccipital punction and can be undertaken in patients with rised intracranial pressure In 62 cases the tap was negative; this led to the diagnosis of amygdaline herniation and the procedure was interrupted without mishap. The authors consider that, in the future, the connection of the cisternal catheter with a transducer, will permit the continuous monitoring of the intracranial cisternal pressure.