HYDROCEPHALUS

HYDROCEPHALUS

DR PREM PILLAY, SENIOR NEUROSURGEON,
EXPERT IN HYDROCEPHALUS,
SINGAPORE BRAIN+SPINE+NERVES CENTER

Hydrocephalus in adults is a complex and multifaceted condition characterized by an abnormal accumulation of cerebrospinal fluid (CSF) within the ventricles of the brain. This condition can result from a variety of etiologies, leading to increased intracranial pressure and subsequent neurological impairment. The management of adult hydrocephalus requires a nuanced understanding of its pathophysiology, clinical presentation, diagnostic modalities, and therapeutic interventions.

Etiology and Pathophysiology

Adult hydrocephalus can be classified into several categories based on its underlying cause: obstructive (non-communicating), communicating, and ex-vacuo hydrocephalus. Obstructive hydrocephalus arises from a physical blockage within the ventricular system or at the outlets of the fourth ventricle, impeding the flow of CSF. Common causes include tumors, such as colloid cysts , pineal tumors, gliomas including tectal gliomas, and aqueductal stenosis, which may be congenital or acquired due to inflammation or hemorrhage.

Communicating hydrocephalus, on the other hand, occurs despite the absence of an obstruction in the ventricular system. It is often attributed to impaired CSF absorption at the arachnoid granulations, which can be secondary to subarachnoid hemorrhage, hemorrhagic strokes, meningitis, or idiopathic normal pressure hydrocephalus (iNPH). Ex-vacuo hydrocephalus is a misnomer, as it reflects ventricular enlargement secondary to brain atrophy rather than true hydrocephalus, and is commonly seen in neurodegenerative diseases such as Alzheimer’s Dementia.

Clinical Presentation

The clinical presentation of hydrocephalus in adults can vary widely. Symptoms may develop acutely or slowly, depending on the rate of CSF accumulation and the underlying pathology. Classic manifestations include headaches, nausea, vomiting, blurred vision, and papilledema, indicative of raised intracranial pressure. In contrast, iNPH is characterized by a triad of gait disturbance, cognitive impairment, and urinary incontinence, often with normal or only slightly elevated intracranial pressure.

Diagnostic Evaluation

Clinical findings are supported by imaging studies, which are essential for diagnosis and treatment planning. Computed tomography (CT) and magnetic resonance imaging (MRI) are the primary modalities used to assess ventricular size, identify potential causes of CSF flow obstruction, and evaluate for transependymal CSF flow. MRI provides superior soft tissue contrast and can delineate the anatomy of the ventricular system and surrounding structures in greater detail. Patients with suspected Normal Pressure Hydrocephalus often have a lumbar spine CSF tap to observe any improvement in their symptoms such as gait before having a programable ventriculoperitoneal shunt (VP shunt) placement states Dr Prem Pillay.

Treatment

The cornerstone of hydrocephalus management is the diversion of CSF to reduce intracranial pressure and alleviate symptoms. Ventriculoperitoneal (VP) shunts are the most commonly employed devices, consisting of a proximal catheter placed within the lateral ventricle, a valve mechanism to regulate flow, and a distal catheter that terminates in the peritoneal cavity. Alternatives include ventriculoatrial (VA) and lumboperitoneal (LP) shunts, which are selected based on patient-specific anatomical and physiological considerations.

Endoscopic third ventriculostomy (ETV) is a minimally invasive surgical option for obstructive hydrocephalus, which involves creating an opening in the floor of the third ventricle to allow CSF to bypass the obstruction and flow directly into the subarachnoid space. ETV is associated with lower infection rates and may reduce the need for shunt placement, particularly in patients with aqueductal stenosis or tectal gliomas.

Microsurgical removal of tumors obstructing the CSF pathways may also relieve hydrocephalus without needing to place a shunt or do an ETV. Examples of this including removing a large cerebellar tumor that is compressing the fourth ventricle and causing hydrocephalus explains Dr Prem Pillay.

Latest and Future Innovations

Advancements in neuroimaging, including the development of phase-contrast MRI techniques, are enhancing the ability to visualize CSF dynamics and may lead to improved diagnostic accuracy. The integration of machine learning algorithms with imaging data holds promise for predicting shunt responsiveness and optimizing patient selection for ETV.

Neuronavigation with computer aided Image guidance allows the more precise placement of Ventricular shunts reducing bleeding and obstruction. Robotics may also improve the precision of shunt placements.

Neuroendoscopic innovations continue to evolve, with the advent of flexible endoscopes and improved intraventricular navigation systems, potentially expanding the indications for ETV and enhancing surgical outcomes. Additionally, the development of programmable shunt valves and telemetric pressure sensors is refining the management of shunt systems, allowing for non-invasive adjustments and monitoring to prevent over- or under-drainage complications.

In the realm of molecular biology, research into the pathophysiological mechanisms underlying CSF production and absorption may yield novel pharmacological targets for the treatment of hydrocephalus. Gene therapy and stem cell-based approaches are also being explored as potential avenues for repairing or replacing dysfunctional CSF pathways.

Conclusions

Hydrocephalus in adults is a condition with diverse etiologies and clinical manifestations, requiring a tailored approach to diagnosis and management. Current treatment strategies focus on CSF diversion through shunting or endoscopic procedures, with ongoing research aimed at improving patient outcomes through technological and biological innovations. As our understanding of hydrocephalus deepens, the future holds the potential for more precise and less invasive therapeutic options explains Dr Prem.