Normal-pressure Hydrocephalus. Relationship Between Sleep Apnea and Intracranial and Intraabdominal Pressures. Outcome Prognostic Factors in CSF Shunting. Features Guiding to Implant a Ventricle-peritoneal Versus a Ventriculo-atrial Shunt

Chronic hydrocephalus in adults, also known as normal pressure hydrocephalus or normal pressure hydrocephalus, occurs with the classic Hakim-Adams triad, gait ataxia, or "magnetic gait", urinary incontinence and dementia.

Most of the cases have an idiopathic origin and are the only potentially reversible cause of dementia with surgical treatment (by shunting the cerebrospinal fluid or CSF from the lateral ventricles or the thecal sac to the peritoneal cavity or the right atrium), so it is especially important to diagnose it and treat it properly.

Unfortunately, and despite all the diagnostic arsenal, the results of treatment using cerebrospinal fluid shunts (lumbo-peritoneal or ventricle-peritoneal), even in the best series, show 20-25% of poor results. These poor results have been attributed to many factors, including associated cerebral vascular pathology problems, co-existing dementia symptoms not always well diagnosed, Parkinson's disease, and, lastly, alterations in ventilatory rhythm. during the night, specifically obstructive sleep apnea or OSA.

In reality, the name of normotensive hydrocephalus or hydrocephalus at normal pressure is inaccurate because the intracranial pressure does rise and very markedly during sleep, particularly during the REM phase of sleep. What is no longer so well known is because of such significant increases in intracranial pressure occur. One possible explanation would be that obstructive sleep apnea causes increased intracranial pressure. But it remains to be clarified whether all patients with adult chronic hydrocephalus have sleep apnea, the mechanism of action, and to what extent the treatment of hydrocephalus acts on sleep apnea and vice versa.

Another aspect to consider is that the cerebrospinal fluid shunts work by the pressure gradient between the intracranial cavity and the cavity into which the cephalo-spinal fluid is drained66, usually the peritoneal fluid. During sleep apnea, there should be an increase in intra-abdominal pressure, which would result in the ventricle-peritoneal and lumbo-peritoneal shunts working suboptimally precisely at the time of day when they are most needed, that is when intracranial pressure increases. But this correlation has never been investigated or at least there are no publications about it.