An elementary technique for discontinuously measuring intracranial pressure, ventricular chemistry, cellularity, and topography, employing percutaneous needle tapping of an implanted module consisting of a Rickham reservoir-ventricular catheter for the chronic monitoring of severe head injury patients is presented. The intracranial pathophysiological conditions (increased ICP, persistent CSF cellularity, xanthochromia and elevated protein levels, and hydrocephalus) occurring in seven so instrumented patients recovering from such injuries are reviewed. The simplicity, safety, and multidiagnostic capability of the system are emphasized.