Neurosurgery

Each disease with the image that defines it: what it looks like, what the scan shows, and which operation answers it.

Traumatic intracranial haematomas

Same skull, three spaces, three time courses.

Extradural

Arterial blood between skull and dura, classically from the middle meningeal artery under a pterional fracture: the lens on CT, the lucid interval in the history, and the best outcomes in neurosurgery when evacuated fast.

Acute subdural

Venous or cortical bleeding beneath the dura in higher-energy injury: the crescent on CT, an injured brain underneath, and outcomes that depend as much on the brain as on the clot.

Chronic subdural

The elderly, anticoagulated, atrophic-brain version: weeks of gradual decline, a liquid collection, and burr-hole drainage as one of the specialty's most rewarding operations.

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The shared physics

All three obey Monro-Kellie: the difference is speed. Arterial bleeding outruns compensation in hours; chronic collections negotiate with it for weeks; and in every case the falling GCS is the compensation running out.

Management logic

Size, shift and neurology decide: significant clots with deficit are evacuated; small collections with intact examination may be watched with serial imaging and obsessive observations, with anticoagulation reversed either way.

Craniotomy for extradural haematomaBurr-hole drainage of chronic subduralCase: Talked, then deteriorated Case: Confused since the autumn

CT

What should I notice?

• Aneurysmal subarachnoid haemorrhage

  A burst berry, and three enemies queuing behind it.

  The event

  A saccular aneurysm at a circle-of-Willis branch point ruptures into the subarachnoid space: thunderclap headache, meningism, and a spectrum from headache-only to coma graded at presentation.

  Securing the aneurysm

  Rebleeding is the early killer, so the aneurysm is secured within a day or two: endovascular coiling for most, surgical clipping for some, chosen by anatomy in a joint neurovascular conversation.

  Vasospasm

  Days 4 to 14: irritated vessels narrow, and delayed cerebral ischaemia can infarct territory the bleed spared. Nimodipine, euvolaemia and daily vigilance for new deficit are the countermeasures.

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  Hydrocephalus

  Blood clogs the CSF's absorption: acute hydrocephalus may need an external ventricular drain in the first days, and a fraction of survivors need a permanent shunt.

  External ventricular drain insertionCase: The worst headache of her life

• Hydrocephalus & CSF disorders

  A circulation problem in a fluid most people forget is circulating.

  The circulation

  CSF is made in the ventricles' choroid plexus, flows through the ventricular system, and is absorbed over the brain's surface: about half a litre a day through a system with millimetre-scale bottlenecks.

  Obstruction and its kinds

  Block the aqueduct or a foramen and the ventricles upstream balloon (obstructive); impair absorption after haemorrhage or meningitis and the whole system fails (communicating). The CT pattern hints at which.

  Relief

  The external ventricular drain is the acute answer, temporary, measurable, adjustable; shunts (usually ventriculoperitoneal) are the chronic one; endoscopic third ventriculostomy bypasses obstruction internally in selected anatomy.

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  Living with a shunt

  Shunts fail: blockage, disconnection, infection, over-drainage. Every shunted patient's acute presentation starts with the question 'could this be the shunt?', and the answer requires comparison imaging and neurosurgical involvement.

  External ventricular drain insertionCase: The shunt that stopped working

• Cauda equina & spinal cord compression

  The spine's emergencies, where hours decide decades.

  Two syndromes

  Compression above the cord's end (around L1) injures cord: upper motor neuron signs, a sensory level. Below it, the cauda equina's roots are crushed: flaccid weakness, saddle anaesthesia, sphincter failure. The level decides the syndrome.

  The causes

  Massive disc prolapse for cauda equina; metastatic disease is the great cause of cord compression, sometimes as cancer's first sign; abscess and haematoma complete the urgent list.

  Recognition

  The red-flag questions (saddle numbness, retention, bilateral symptoms) plus a bladder scan and rectal examination: objective findings gathered before the MRI, because the MRI queue moves on documented suspicion.

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  Treatment and stakes

  Emergency MRI, then decompression with real urgency; steroids and oncology enter for malignant compression. Function present at surgery can be kept; function lost before it returns unreliably, which is the whole argument for speed.

  Case: Back pain, and numbness where he sits