The Efficacy of Endoscopic Third Ventriculostomy for Idiopathic Normal Pressure Hydrocephalus

Biomechanical instability of the brain-CSF interface in hydrocephalus

Hydrocephalus, characterized by progressive expansion of the CSF-filled ventricles (ventriculomegaly), is the most common reason for brain surgery. 'Communicating' (i.e. non-obstructive) hydrocephalus is classically attributed to a primary derangement in CSF homeostasis, such as choroid plexus-dependent CSF hypersecretion, impaired cilia-mediated CSF flow currents, or decreased CSF reabsorption via the arachnoid granulations or other pathways. Emerging data suggest that abnormal biomechanical properties of the brain parenchyma are an under-appreciated driver of ventriculomegaly in multiple forms of communicating hydrocephalus across the lifespan. We discuss recent evidence from human and animal studies that suggests impaired neurodevelopment in congenital hydrocephalus, neurodegeneration in elderly normal pressure hydrocephalus and, in all age groups, inflammation-related neural injury in post-infectious and post-haemorrhagic hydrocephalus, can result in loss of stiffness and viscoelasticity of the brain parenchyma. Abnormal brain biomechanics create barrier alterations at the brain-CSF interface that pathologically facilitates secondary enlargement of the ventricles, even at normal or low intracranial pressures. This 'brain-centric' paradigm has implications for the diagnosis, treatment and study of hydrocephalus from womb to tomb.

Treatment of post-thalamic hemorrhage hydrocephalus: ventriculoperitoneal shunt or endoscopic third ventriculostomy? A retrospective observational study

BACKGROUND

The aim of this study was to compare the efficacy of ventriculoperitoneal shunt (VPS) and endoscopic third ventriculostomy (ETV) for the treatment of hydrocephalus after thalamic hemorrhage (TH) where external ventricular drainage (EVD) could not be removed after hematoma absorption, and to provide a theoretical basis for the clinical treatment of hydrocephalus after TH.

METHODS

The clinical data of patients with hydrocephalus after TH whose EVD could not be removed after hematoma absorption were retrospectively analyzed. According to the patients' surgical methods, the patients were divided into the VPS group and ETV group. The operative time, length of hospital stay, complications, and reoperation rates of the two groups were compared.

RESULTS

There was no statistically significant difference in intraoperative bleeding, length of hospital stay between the two groups. The EVD tubes were successfully removed in all patients after surgery. There were 4 (9.5%) complications in the ETV group and 3 (6.7%) complications in the VPS group, with no statistically significant difference in postoperative complications between the two groups. During the 1-year follow-up, 7 patients (16.7%) in the ETV group and 3 patients (6.7%) in the VPS group required reoperation. In the subgroup analysis of TH combined with fourth ventricular hemorrhage, 6 patients (14.3%) in the ETV group and 1 patient (2.2%) in the VPS group required reoperation, and the difference between the two groups was statistically significant.

CONCLUSIONS

ETV had good efficacy in treating hydrocephalus caused by TH and TH that broke into the lateral ventricle and the third ventricle. However, if hydrocephalus was caused by TH with the fourth ventricular hematoma, VPS was a better surgical method because the recurrence rate of hydrocephalus in ETV was higher than that in VPS. Therefore, the choice of surgical method should be based on the patient's clinical features and hematoma location.

Pathogenesis and management of low-pressure hydrocephalus: A narrative review

Patients diagnosed with low-pressure hydrocephalus typically present with enlarged ventricles and unusually low intracranial pressure, often measuring below 5 cmH2O or even below atmospheric pressure. This atypical presentation often leads to low recognition and diagnostic rates. The development of low-pressure hydrocephalus is believed to be associated with a decrease in the viscoelasticity of brain tissue or separation between the ventricular and subarachnoid spaces. Risk factors for low-pressure hydrocephalus include subarachnoid hemorrhage, aqueduct stenosis, prior cranial radiotherapy， ventricular shunting, and cerebrospinal fluid leaks. For potential low-pressure hydrocephalus, diagnostic criteria include neurological symptoms related to hydrocephalus, an Evans index >0.3 on imaging, ICP ≤ 5 cm H2O, symptom improvement with negative pressure drainage, and exclusion of ventriculomegaly caused by neurodegenerative diseases. The pathogenesis and pathophysiological features of low-pressure hydrocephalus differ significantly from other types of hydrocephalus, making it challenging to restore normal ventricular morphology through conventional drainage methods. The primary treatment options for low-pressure hydrocephalus involve negative pressure drainage and third ventriculostomy. With appropriate treatment, most patients can regain their previous neurological function. However, in most cases, permanent shunt surgery is still necessary. Low-pressure hydrocephalus is a rare condition with a high rate of underdiagnosis and mortality. Early identification and appropriate intervention are crucial in reducing complications and improving prognosis.

Utility of cortical tissue analysis in normal pressure hydrocephalus

Clinical improvement following neurosurgical cerebrospinal fluid shunting for presumed idiopathic normal pressure hydrocephalus is variable. Idiopathic normal pressure hydrocephalus patients may have undetected Alzheimer's disease-related cortical pathology that confounds diagnosis and clinical outcomes. In this study, we sought to determine the utility of cortical tissue immuno-analysis in predicting shunting outcomes in idiopathic normal pressure hydrocephalus patients. We performed a pooled analysis using a systematic review as well as analysis of a new, original patient cohort. Of the 2707 screened studies, 3 studies with a total of 229 idiopathic normal pressure hydrocephalus patients were selected for inclusion in this meta-analysis alongside our original cohort. Pooled statistics of shunting outcomes for the 229 idiopathic normal pressure hydrocephalus patients and our new cohort of 36 idiopathic normal pressure hydrocephalus patients revealed that patients with Aβ + pathology were significantly more likely to exhibit shunt nonresponsiveness than patients with negative pathology. Idiopathic normal pressure hydrocephalus patients with Alzheimer's disease -related cortical pathology may be at a higher risk of treatment facing unfavorable outcomes following cerebrospinal fluid shunting. Thus, cortical tissue analysis from living patients may be a useful diagnostic and prognostic adjunct for patients with presumed idiopathic normal pressure hydrocephalus and potentially other neurodegenerative conditions affecting the cerebral cortex.