Hydrocephalus

Which hydrocephalus, and is it compensated - Acute obstructive hydrocephalus behaves like any expanding intracranial mass: dilated nonreactive pupil, autonomic dysfunction, loss of brainstem reflexes, coma, and it needs immediate decompression. A chronically shunted patient coming for something unrelated is an entirely different case. Establish which one you have before you write a plan.

Signs the pressure is not controlled - Headache, neck pain, explosive vomiting, drowsiness, blurred vision or diplopia, failure of upward gaze, gait instability, confusion, and seizures. In infants: tense or bulging fontanelle, split sutures, setting-sun sign, poor feeding, high-pitched cry, and a "cracked pot" note on skull percussion.

Is the shunt working - Ask specifically about headache, lethargy, diplopia, nausea and vomiting, seizure, irritability, poor feeding, tense fontanelle, fever, and neck rigidity, and palpate the shunt tract for redness or swelling. The objective workup is a shunt series to check hardware integrity plus CT or MRI for ventricular size — get those results before an elective case, not after one goes wrong.

No lumbar puncture until the imaging is back - LP in a patient with raised ICP can drop pressure suddenly, and that volume shift can herniate the brain. Brain imaging comes first. This is why the undiagnosed hydrocephalic is a hazard for a routine spinal.

Full stomach - Vomiting is a presenting symptom of the disease, not a coincidence. Treat these patients as aspiration risks and plan RSI.

Ventilation - Hypercarbia dilates cerebral vessels and adds volume the vault has no room for. For shunt placement the surgeon may ask for an EtCO2 of 25 to 30, so clarify the target before you drape; cerebral vasoconstriction is already maximal below a PaCO2 of 25 mmHg and the effect washes out within 6 to 18 hours.

Set up for no access - A VP shunt is supine with arms tucked and the table turned 90 degrees and pushed out so two teams can work the head and the abdomen at once. Get two IVs and circuit extensions in before that happens — the machine ends up 5 to 10 feet away and you cannot reach the patient once the drapes are up.

Recheck the tube after positioning - The head is turned to one side with slight forward flexion, and Mayfield pins may go on. Auscultate and confirm ETT depth after the surgeons finish positioning; flexion walks the tube toward the right mainstem.

Three moments that will move the hemodynamics - Peritoneal insufflation gives a vagal response with bradycardia and blood pressure change. Opening the ventricle relieves pressure around the brainstem and can drop the blood pressure abruptly, so have phenylephrine drawn up. Subcutaneous tunneling of the catheter is intensely stimulating and will spike heart rate and pressure — deepen ahead of it rather than chasing it.

OG tube - The team will usually want an orogastric tube to low suction for gastric decompression, since the abdomen is part of the field.

Long-case housekeeping - Two to four hours with tucked arms means a urinary catheter, an IV fluid warmer, forced-air warming, and periodic checks of lines and pressure points you cannot see.

The NPH patient - Elderly, with the gait, cognitive, and urinary triad, often arriving after a high-volume LP of 30 to 50 mL or a lumbar drain trial used to predict shunt response. Document a cognitive baseline; this patient carries the delirium risk of any elderly demented patient on top of the neurosurgery.

The distal end is not always peritoneal - When the peritoneum has failed, the catheter is routed to the atrium or the pleura instead. Confirm which one you have before the case; it changes what the distal incision can do to you.

Hydrocephalus is the symptomatic accumulation of cerebrospinal fluid inside the cerebral ventricles — from obstruction of flow, failed absorption at the arachnoid granulations, or overproduction. The choroid plexus makes roughly 500 mL of CSF a day against a standing volume of about 150 mL, so the entire pool turns over about three times every 24 hours and small shifts in absorption show up fast. Adults get four types: obstructive, communicating, hypersecretory, and normal pressure hydrocephalus. Communicating hydrocephalus is usually post-hemorrhagic or post-inflammatory, with subarachnoid hemorrhage alone accounting for a third of cases.

Because the vault is fixed (Monro-Kellie), accumulating CSF raises ICP, forces transependymal fluid into brain tissue, and causes pressure atrophy. Acute hydrocephalus without prompt treatment ends in herniation and death. Normal pressure hydrocephalus sits at the other extreme — a slow elderly presentation with the Hakim triad of gait impairment, cognitive decline, and urinary urgency or incontinence.