The fate of the cerebrospinal fluid after neuroendoscopic third ventriculostomy.

This paper describes the case of a 9-year-old girl with a posterior thalamic/pineal region lesion and secondary obstructive hydrocephalus. The hydrocephalus was treated by neuroendoscopic third ventriculostomy (NTV), and she underwent simultaneous transendoscopic biopsy. The tumour biopsy was haemorrhagic, but the bleeding settled with constant irrigation. The patient remained neurologically unchanged, but subsequent imaging revealed an asymptomatic thoracolumbar spinal subdural haematoma thought to be due to blood flowing out through the NTV into the subdural space. This demonstrates the subdural location of the cerebrospinal fluid after NTV.