Cerebral blood oxygenation after cerebrospinal fluid removal in hydrocephalus measured by near infrared spectroscopy.

Background: The cerebrospinal fluid (CSF) tap test has been used for the diagnosis of chronic hydrocephalus to identify the candidates for surgical CSF shunting. However, a high rate of false negative results limits it utility. The purpose of this study is to investigate whether the concomitant monitoring of cerebral hemodynamics by near infrared spectroscopy (NIRS) can improve the diagnostic accuracy of the tap test.

Methods: Thirteen patients with dilated ventricular system were candidates for this study. We assessed for the patterns of cerebral blood oxygenation (CBO) change in hydrocephalus to determine whether CBO change after CSF removal is useful for selecting shunt candidates.

Results: Patients who showed clinical improvement following CSF shunting had a characteristic CBO change with increases in the concentration of oxyhemoglobin (Oxy-Hb), and patients without improvement during continuous CSF drainage test showed no increase in Oxy-Hb.

Conclusion: The current data suggests that CBF increases after CSF removal in hydrocephalus. Although the patients utilized in the present study had secondary chronic hydrocephalus, we speculate that these data could be applied to patients with idiopathic chronic hydrocephalus. Further investigation would be of benefit.