11.5 Neurosurgery: Raised ICP, Head Injury & CNS Lesions
Key Takeaways
- Raised intracranial pressure presents with headache (worse on waking, coughing, bending), vomiting, papilloedema and falling GCS; Cushing's triad (bradycardia, hypertension, irregular respiration) signals imminent herniation.
- Extradural haematoma (lens-shaped, middle meningeal artery, lucid interval) and acute subdural haematoma (crescent-shaped, bridging veins, worse prognosis) are the classic traumatic bleeds distinguished on CT.
- Glasgow Coma Scale (eye 4 + verbal 5 + motor 6 = 15) stratifies head-injury severity; a deteriorating GCS or pupil asymmetry mandates urgent CT and neurosurgical referral.
- Cord compression is a surgical emergency — back pain progressing to weakness, sensory level and sphincter disturbance needs urgent MRI and decompression within hours to preserve function.
- Hydrocephalus (obstructive or communicating) is treated by shunting (VP shunt) or endoscopic third ventriculostomy; CNS tumours (glioma, meningioma, pituitary adenoma, acoustic neuroma) are managed by resection, debulking and adjuvant therapy guided by histology.
11.5 Neurosurgery: Raised ICP, Head Injury & CNS Lesions
High-Yield Core Concept: The Surgery syllabus lists Neurosurgery as a distinct specialty. CMS questions cluster on the time-critical triad — recognising raised ICP, reading the traumatic CT bleed pattern, and spotting spinal cord compression before function is lost.
1. Raised Intracranial Pressure (ICP)
Normal ICP is 5–15 mmHg. Raised ICP (>20 mmHg sustained) reduces cerebral perfusion pressure (CPP = MAP − ICP) and risks herniation.
Clinical features:
- Headache — worst on waking, aggravated by coughing/straining/bending.
- Vomiting — often effortless, without preceding nausea.
- Papilloedema on fundoscopy.
- Altered consciousness / falling GCS.
- Cushing's triad (late, pre-terminal): bradycardia, hypertension (wide pulse pressure), irregular respiration.
Herniation syndromes:
| Syndrome | Mechanism | Signs |
|---|---|---|
| Uncal (commonest) | Medial temporal lobe through tentorial hiatus | Ipsilateral dilated pupil (CN III palsy), contralateral hemiparesis |
| Central | Bilateral downward displacement | Bilateral small pupils, decorticate posturing |
| Tonsillar | Cerebellar tonsils through foramen magnum | Neck stiffness, respiratory arrest |
Management: elevate head 30°, maintain oxygenation/ventilation (target PaCO₂ 35–40 mmHg), osmotic therapy (mannitol 0.5–1 g/kg or hypertonic saline), treat the cause (tumour, haematoma, hydrocephalus) and ICP monitoring in severe TBI.
2. Traumatic Brain Injury & Intracranial Bleed
Glasgow Coma Scale (GCS) — eye (1–4), verbal (1–5), motor (1–6); max 15, min 3. Severity: mild 13–15, moderate 9–12, severe ≤8 (intubate if ≤8).
| Haematoma | Source | CT appearance | Notes |
|---|---|---|---|
| Extradural | Middle meningeal artery (temporal fracture) | Lens/biconvex, does not cross sutures | Lucid interval then deterioration; good prognosis if evacuated early |
| Acute subdural | Bridging veins | Crescent, crosses sutures, follows brain surface | Worse prognosis; underlying brain injury |
| Subarachnoid | Cortical vessels | Blood in sulci/cisterns | Traumatic or spontaneous (berry aneurysm) |
| Intracerebral | Parenchymal contusion | Mixed density within brain | Delayed 'blossom' on repeat CT |
Indications for urgent CT: GCS <13 (or <15 with risk factors), focal deficit, seizure, repeated vomiting, suspected skull fracture, coagulopathy, age ≥65.
Management principles: ABCDE, cervical spine immobilisation, avoid hypotension/hypoxia (both worsen secondary brain injury), treat raised ICP, surgical evacuation of significant extra-/subdural haematomas, decompressive craniectomy for refractory ICP in selected cases.
3. Spinal Cord Compression
A surgical emergency — outcome depends on speed of decompression. Metastatic disease (breast, lung, prostate, myeloma) and trauma are common causes; epidural abscess and disc herniation in younger patients.
Clinical progression: back pain → radicular pain → weakness (motor) → sensory level → sphincter disturbance (bladder/bowel) → complete cord transection.
Investigation: urgent MRI of the relevant region (whole spine if multiple levels suspected). Plain X-rays and CT may miss soft-tissue cord compression.
Management: urgent decompression within 24 hours (laminectomy/corpectomy) for cord compression with neurological deficit; high-dose dexamethasone for malignant cord compression while arranging definitive treatment; radiotherapy for radiosensitive tumours.
4. Hydrocephalus
Excess CSF from impaired circulation (obstructive/non-communicating) or absorption (communicating).
In infants: enlarging head, bulging fontanelle, sunsetting eyes, vomiting, developmental delay.
In adults: features of raised ICP; normal-pressure hydrocephalus in elderly presents with the triad gait apraxia, dementia and urinary incontinence.
Treatment: ventriculoperitoneal (VP) shunt, or endoscopic third ventriculostomy for obstructive hydrocephalus due to aqueductal stenosis. CSF tap or external drain for acute decompression.
5. Common Intracranial Tumours
| Tumour | Features |
|---|---|
| Glioblastoma multiforme | Most aggressive primary adult tumour; 'butterfly' lesion across corpus callosum, necrotic core, ring enhancement |
| Meningioma | Extra-axial, dural-based, slow-growing, often calcified; more in women |
| Pituitary adenoma | Bitemporal hemianopia (optic chiasm), endocrine syndromes (prolactinoma, acromegaly, Cushing) |
| Acoustic neuroma (schwannoma) | cerebellopontine angle, unilateral hearing loss, tinnitus; NF2 if bilateral |
| Medulloblastoma | Posterior fossa, children, drops via CSF |
Management: maximal safe resection, debulking for symptomatic mass effect, radiotherapy/chemotherapy guided by histology and grade; glucocorticoids to control oedema pre-operatively.
6. Neurosurgical Emergencies & Peri-operative Care
Several non-traumatic neurosurgical presentations are time-critical and frequently examined:
Spontaneous intracerebral haemorrhage — hypertensive bleed (basal ganglia, thalamus, pons, cerebellum) presents with sudden headache, deficit and reduced consciousness. Cerebellar haematoma >3 cm or with brainstem compression is a neurosurgical emergency — posterior-fossa decompression can be life-saving, whereas deep supratentorial bleeds are usually managed medically (BP control, ICP management).
Subarachnoid haemorrhage (SAH) — sudden 'thunderclap' headache, meningism, reduced GCS; non-contrast CT shows subarachnoid blood (sensitive within 6 hours), and CT angiography localises the aneurysm. Definitive treatment is endovascular coiling (preferred where feasible) or surgical clipping; nimodipine prevents delayed cerebral ischaemia.
Status epilepticus and raised ICP from any cause may need neurosurgical input for monitoring (external ventricular drain, intracranial pressure bolt) and decompression.
Peri-operative principles after cranial surgery:
- Maintain cerebral perfusion pressure (CPP 60–70 mmHg): keep MAP adequate, treat raised ICP (head elevation 30°, normocapnia, osmotherapy).
- Avoid hyponatraemia (cerebral salt wasting vs SIADH distinction guides fluid management).
- Seizure prophylaxis in the early post-traumatic period for high-risk patients.
- DVT prophylaxis balanced against bleeding risk; monitor for CSF leak/infection at the wound.
Worked scenario: a 60-year-old hypertensive develops sudden severe headache, vomiting and a left hemiparesis; CT shows a right basal-ganglia haematoma with no midline shift. Initial management is medical (BP control, ICP measures), whereas a cerebellar haematoma with brainstem compression in the same patient would mandate urgent posterior-fossa decompression.
Key Takeaways for the CMS Candidate
- Cushing's triad = late raised-ICP warning; unilateral dilated pupil = uncal herniation.
- Extradural = lens/biconvex + lucid interval; subdural = crescent + worse prognosis.
- GCS ≤8 → intubate; deteriorating GCS or pupil asymmetry → urgent CT.
- Cord compression with deficit = urgent MRI + decompression within 24 hours.
- NPH triad in elderly: gait apraxia + dementia + incontinence.
A young man has a brief loss of consciousness after a temporal head blow, then becomes alert ('talked and died' pattern), then drowsy with a dilated right pupil and left hemiparesis. What is the most likely CT finding?
A 60-year-old with prostate cancer develops thoracic back pain, progressive leg weakness, a T6 sensory level and urinary retention over 48 hours. What is the most appropriate immediate management?