Cerebrospinal fluid markers before and after shunting in patients with secondary and idiopathic normal pressure hydrocephalus

We measured clinical symptoms and analysed lumbar CSF for protein content, neurodegeneration and neurotransmission markers in patients with secondary (SNPH, n = 17) and idiopathic NPH (INPH, n = 18) before and 3 months after shunt surgery. Patients were divided into groups according to whether or not there was improvement in clinical symptoms after surgery.Preoperatively, the only pathological findings were elevated neurofilament protein (NFL), significantly more so in the SNPH patients than in the INPH patients, and elevated albumin content. Higher levels of NFL correlated with worse gait, balance, wakefulness and neuropsychological performance. Preoperatively, no differences were seen in any of the CSF biomarkers between patients that improved after surgery and those that did not improve. Postoperatively, a greater improvement in gait and balance performance correlated with a more pronounced reduction in NFL. Levels of albumin, albumin ratio, neuropeptide Y, vasoactive intestinal peptide and ganglioside GD3 increased significantly after shunting in both groups. In addition, Gamma amino butyric acid increased significantly in SNPH and tau in INPH.We conclude that a number of biochemical changes occur after shunt surgery, but there are no marked differences between the SNPH and INPH patients. The results indicate that NFL may be a marker that can predict a surgically reversible state in NPH.Normal pressure hydrocephalus (NPH) is a common and treatable cause of cognitive impairment and gait disturbance in the elderly[1]. NPH is generally thought of as a disorder resulting from disturbed cerebrospinal fluid (CSF) dynamics. Cerebral blood flow (CBF) is reduced in white and gray matter regions [2-5]. Microdialysis studies indicate compromised metabolism in the periventricular region [6]. Magnetic resonance (MR) images showing periventricular white matter lesions (WML) are a hallmark of NPH, the extent of which correlate with symptomathology [7-9]. After surgery, patient