This paper describes the case of a 9-year-old girl with a posterior thalami
c/pineal region lesion and secondary obstructive hydrocephalus. The hydroce
phalus was treated by neuroendoscopic third ventriculostomy (NTV), and she
underwent simultaneous transendoscopic biopsy. The tumour biopsy was haemor
rhagic, but the bleeding settled with constant irrigation. The patient rema
ined neurologically unchanged, but subsequent imaging revealed an asymptoma
tic thoracolumbar spinal subdural haematoma thought to be due to blood flow
ing out through the NTV into the subdural space. This demonstrates the subd
ural location of the cerebrospinal fluid after NTV.