Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark.
Department of Veterinary Clinical Sciences, University of Copenhagen, Copenhagen, Denmark.
Fluids Barriers CNS. 2022 Jun 27;19(1):52. doi: 10.1186/s12987-022-00349-5.
The etiology of idiopathic normal pressure hydrocephalus (iNPH) is currently unknown. With no visible obstructions, altered cerebrospinal fluid (CSF) dynamics may explain the accumulation of ventricular fluid. We hypothesized that elevated osmolality in the CSF of iNPH patients could potentiate formation of ventricular fluid and thereby cause the disease progression and/or predict the surgical outcome. To address this hypothesis, we determined the lumbar and ventricular CSF osmolality of iNPH patients at different disease stages and compared with lumbar CSF samples obtained from control subjects.
The osmolality of CSF was determined on a total of 35 iNPH patients at diagnosis and at the subsequent treatment with shunt surgery (n = 20) and compared with the CSF osmolality from 20 control subjects. Simultaneously collected lumbar and ventricular CSF samples from experimental pigs were used to evaluate the compatibility between CSF from different compartments.
We found no evidence of increased osmolality in the CSF of iNPH patients upon diagnosis or at the time of shunt treatment months after the diagnosis, compared with control individuals. CSF tapped from the lumbar space could be used as a read-out for ventricular CSF osmolality, as these were similar in both the patient group and in experimental pigs. We further observed no correlation between the CSF osmolality in iNPH patients and their responsiveness to shunt surgeries.
The osmolality of lumbar CSF is a reliable reflection of the ventricular CSF osmolality, and is not elevated in iNPH patients. iNPH therefore does not appear to arise as a function of osmotic imbalances in the CSF system and CSF osmolality cannot serve as a biomarker for iNPH or as a predictive tool for shunt responsiveness.
特发性正常压力脑积水（iNPH）的病因目前尚不清楚。由于没有明显的阻塞，脑脊液（CSF）动力学的改变可能解释了脑室液的积聚。我们假设 iNPH 患者 CSF 中的渗透压升高可能增强脑室液的形成，从而导致疾病进展和/或预测手术效果。为了验证这一假设，我们测定了不同疾病阶段 iNPH 患者的腰穿和脑室内 CSF 渗透压，并与对照组的腰穿 CSF 样本进行了比较。
我们对总共 35 名 iNPH 患者在诊断时以及随后接受分流手术治疗（n=20）时的 CSF 渗透压进行了测定，并与 20 名对照组的 CSF 渗透压进行了比较。同时从实验猪收集了腰穿和脑室内 CSF 样本，以评估不同部位 CSF 的相容性。
与对照组相比，我们在 iNPH 患者诊断时或诊断后数月进行分流治疗时，均未发现 CSF 渗透压升高的证据。从腰椎间隙抽取的 CSF 可以作为脑室内 CSF 渗透压的替代指标，因为患者组和实验猪的脑脊液渗透压相似。我们还观察到 iNPH 患者的 CSF 渗透压与他们对分流手术的反应之间没有相关性。
腰穿 CSF 的渗透压是脑室内 CSF 渗透压的可靠反映，在 iNPH 患者中并未升高。因此，iNPH 似乎不是 CSF 系统渗透压失衡的结果，CSF 渗透压不能作为 iNPH 的生物标志物或作为分流反应性的预测工具。
