Hydrocephalus & ICP Management

Overview

This lecture covers the identification and management of hydrocephalus and intracranial pressure (ICP) monitoring in trauma patients, emphasizing external ventricular drain placement, clinical decision-making, and current guideline controversies.

Hydrocephalus: Recognition and Initial Steps

• Hydrocephalus is commonly seen in trauma or unknown etiology cases on head CT with ventricular enlargement.
• Assess for obstructive lesions or masses before considering cerebral spinal fluid (CSF) diversion.
• Initial treatment focuses on relieving hydrocephalus to reduce brain tissue compression.
• Intraventricular hemorrhage may complicate management; clotted drains might require additional interventions.

External Ventricular Drain (EVD) Placement

• EVD placement is life-saving for acute hydrocephalus.
• Standard approach: 12 cm behind the nasion and 4.5 cm lateral from midline, aiming towards the ipsilateral medial canthus and contralateral tragus.
• Proper trajectory is slightly inward and posterior when viewed from above.
• Understanding ventricular anatomy is crucial for correct placement.

Intracranial Pressure Monitoring: Guidelines & Indications

• ICP monitoring indicated in traumatic brain injury (TBI) with Glasgow Coma Scale (GCS) ≤ 8 and abnormal head CT.
• Even with a normal CT, monitoring is considered if the patient has a severe mechanism of injury, poor neuro exam, or systemic risk factors (e.g., low systolic BP).
• Diffuse axonal injury (DAI) can warrant ICP monitoring, though clinical guidelines and practices vary.
• After craniectomy or craniotomy, the decision to monitor ICP is institution-dependent.

Practice Variability and Guidelines

• Brain Trauma Foundation guidelines are widely referenced but not absolute; local practice and experience influence decisions.
• Institutional protocols and personal/institutional habits may conflict with published guidelines.
• Be aware of controversy and variability, especially in monitoring after certain surgeries or with DAI.

ICP Monitoring and Management Algorithms

• Persistent ICP > 20–22 mmHg for over two minutes prompts intervention (mannitol, hypertonic saline, head elevation, short-term hyperventilation).
• Intractable ICP may require surgical decompression (decompressive craniectomy).
• Monitoring may be intraoperative or postoperative if brain swelling, hypoxia, or hypertension is suspected.

Key Terms & Definitions

• Hydrocephalus — Accumulation of CSF causing ventricular enlargement and increased intracranial pressure.
• External Ventricular Drain (EVD) — Device placed to drain CSF from the ventricles and monitor ICP.
• Intracranial Pressure (ICP) — The pressure inside the skull, normally < 20 mmHg.
• Glasgow Coma Scale (GCS) — Clinical scale to assess consciousness in TBI; ≤ 8 indicates severe injury.
• Diffuse Axonal Injury (DAI) — Widespread injury of brain white matter, often without focal lesions on imaging.
• Cerebral Spinal Fluid (CSF) Diversion — Technique to relieve hydrocephalus by draining CSF.

Action Items / Next Steps

• Familiarize yourself with external ventricular drain anatomical landmarks and trajectory.
• Review Brain Trauma Foundation guidelines regarding ICP monitoring indications.
• Be prepared to discuss local institutional protocols and recognize potential controversies in practice.
• Practice communicating the rationale for CSF diversion and ICP monitoring choices on the wards.