From the Guidelines
Yes, increased intracranial pressure (ICP) from hydrocephalus can cause direct pressure effects on the brainstem resulting in cranial nerve dysfunction, also known as craniopathy. When cerebrospinal fluid (CSF) accumulates excessively in the ventricular system due to hydrocephalus, it creates elevated pressure throughout the intracranial compartment. This pressure can directly compress the brainstem, where many cranial nerves originate or traverse. The most commonly affected cranial nerves include the abducens nerve (CN VI), causing lateral gaze palsy, and the oculomotor nerve (CN III), resulting in pupillary dilation and downward eye deviation. Trochlear nerve (CN IV) dysfunction may also occur. This compression happens because the brainstem sits in a relatively fixed position at the base of the skull, making it vulnerable to pressure effects. Additionally, downward herniation of brain tissue through the foramen magnum (tonsillar herniation) can further compress the lower cranial nerves and brainstem.
Key Considerations
- The current recommendations on managing elevated ICP in patients with hydrocephalus are based on data from small RCTs, retrospective series, systematic reviews, and meta-analyses 1.
- Ventricular drainage should be performed in patients with hydrocephalus contributing to decreased level of consciousness 1.
- Treatment requires urgent reduction of ICP, typically through CSF diversion procedures such as ventriculostomy or shunt placement.
- If left untreated, progressive brainstem compression can lead to respiratory and cardiac dysfunction, and ultimately death.
Management of Hydrocephalus
- The pressure should be lowered by removal of CSF in a volume sufficient to reduce the pressure to 50% of the opening pressure or 200 mm of H2O, whichever is greater 2.
- This should be repeated at least daily for 4 days until the pressure stabilizes to <250 mm H2O.
- If medical therapy with azole antifungals and repeated lumbar punctures fail to stabilize the pressure, lumboperitoneal or other shunting procedures need to be explored with neurosurgery 2.
From the Research
Increased ICP from Hydrocephalus
- Increased intracranial pressure (ICP) can be caused by various factors, including hydrocephalus, which is characterized by the excessive accumulation of cerebrospinal fluid (CSF) in the ventricles or skull 3.
- Hydrocephalus can lead to elevated ICP, which can cause direct pressure effects on the brainstem, potentially resulting in craniopathy 4.
- The management of elevated ICP is crucial to prevent cerebral hypoperfusion and possible brain death, and it involves medical and surgical options, including CSF drainage and decompression of surgical lesions 4, 5.
Direct Pressure Effect on the Brainstem
- The direct pressure effect of increased ICP on the brainstem can cause various clinical signs, including headache, papilledema, nausea, and vomiting, followed by stupor and coma, pupillary changes, hemiparesis or quadriparesis, posturing, and respiratory abnormalities 4.
- The use of osmotherapy, such as mannitol and hypertonic saline, is considered the mainstay of medical therapy for elevated ICP, and it should be administered as soon as possible to maintain or re-establish adequate cerebral blood flow and prevent herniation 5, 6.
- The measurement of ICP is essential for the diagnosis and management of hydrocephalus, and it can be performed using various methods, including overnight monitoring of ICP and constant-rate infusion studies 7.
Craniopathy
- Craniopathy refers to a condition characterized by abnormal pressure on the brainstem and cranial nerves, which can be caused by various factors, including increased ICP due to hydrocephalus 4.
- The treatment of craniopathy involves addressing the underlying cause of the condition, which may include the management of elevated ICP using medical and surgical options 4, 5.
- Further research is needed to investigate the medical and surgical options for the treatment of raised ICP and craniopathy, including the use of hypothermia, drugs that reduce cerebral edema, and operations aimed at reducing intracranial mass effect 4.