Neurosurgical Triage at a Glance
The following categorises the most common neurosurgical presentations by urgency. When in doubt — seek care immediately. Time-critical conditions can deteriorate within hours or minutes.
Thunderclap Headache
Worst headache of life, sudden onset. SAH until proven otherwise. CT head immediately.
Cauda Equina Syndrome
Bilateral leg weakness + bladder/bowel dysfunction + saddle anaesthesia. Surgical emergency within 24h.
Acute Stroke (FAST)
Face droop, arm weakness, speech slur, time. tPA window 4.5h. Every minute counts.
Status Epilepticus
Seizure >5 minutes or 2+ seizures without recovery. IV benzodiazepine immediately.
Acute Spinal Cord Compression
Acute paralysis ± sensory level ± bladder retention after trauma. Immobilise + emergency MRI.
Pituitary Apoplexy
Sudden severe headache + visual loss + diplopia. Haemorrhage into pituitary adenoma. Emergency surgery.
New Focal Neurological Deficit
New weakness, numbness, speech problem persisting >1h. Urgent MRI brain + neurosurgical review.
First Adult Seizure
Brain MRI, EEG, bloods. Structural cause must be excluded. Review within 48h.
Progressive Headache + Vomiting
Increasing headache over days-weeks with vomiting. Raised ICP must be excluded. CT head urgently.
Rapidly Worsening Back Pain
Back pain with new neurological symptoms (leg weakness, bladder change). Urgent MRI spine.
Chronic Back / Neck Pain
No red flags. Conservative management. Neurosurgical review if failing physiotherapy × 6 weeks.
Mild Sciatica (Stable)
Unilateral leg pain with no neurological deficit. Conservative trial 6–12 weeks. Planned consultation.
Thunderclap Headache
"Worst Headache of My Life" · Sudden Onset · Peaking Within 60 Seconds
A thunderclap headache is a severe headache that reaches maximum intensity within 60 seconds of onset, often described as the "worst headache of my life." It must be treated as subarachnoid haemorrhage (SAH) until proven otherwise. SAH accounts for 10–15% of thunderclap headaches, but misdiagnosis is the most common medicolegal error in emergency medicine.
Send every patient with a thunderclap headache for CT head immediately — even if they "look well." 30% of missed SAH patients die or have permanent disability on rebleed. A normal CT does NOT exclude SAH — LP at 12h is mandatory if CT negative within 6h of onset.
Differential Diagnosis of Thunderclap Headache
| Cause | Key Features | Investigation | Urgency |
|---|---|---|---|
| SAH (Aneurysm Rupture) | Exertional onset, meningism, vomiting, photophobia, LOC | CT head → LP if CT negative | Emergency |
| Sentinel Bleed (pre-SAH) | Milder thunderclap, may resolve; 10–20% precede full SAH | CT + LP essential; do not miss | Emergency |
| RCVS (Reversible Cerebrovascular) | Recurrent thunderclap over days-weeks; often triggered by sex, exertion, Valsalva | MRA for arterial spasm; treat conservatively | Urgent |
| Cerebral Venous Thrombosis | Progressive headache ± seizures ± post-partum; thunderclap in 10% | MRI + MRV | Urgent |
| Hypertensive Emergency | BP >180/120, occipital headache, encephalopathy | BP check, CT head, urine protein | Emergency |
| Spontaneous Intracranial Hypotension | Postural headache (worse upright, better lying), CSF leak | MRI with gadolinium (meningeal enhancement) | Urgent |
| Benign Thunderclap (after exclusion) | No secondary cause identified; diagnosis of exclusion only | CT + LP + MRA all negative | Routine |
Ottawa SAH Rule — Validated Decision Rule
In patients ≥15 years with non-traumatic acute severe headache reaching maximum within 1h, investigate for SAH if ANY of the following: Age ≥40 · Neck pain or stiffness · Witnessed LOC · Onset during exertion · Thunderclap character (instantly severe) · Limited neck flexion on exam. All such patients require CT head ± LP regardless of normal neurological exam.
Emergency Management
Sensitivity for SAH: 98–99% within 6h of onset; drops to 85–90% at 24h, ~50% at 1 week. Subarachnoid blood appears as hyperdense (white) filling of basal cisterns (star sign), sylvian fissures, or convexity sulci.
Send CSF for xanthochromia (yellow discolouration from oxyhaemoglobin/bilirubin breakdown) — more reliable than RBC count alone. Xanthochromia present 12h–2 weeks post-SAH. Spectrophotometry preferred over visual inspection.
CTA detects aneurysms ≥3mm with sensitivity >90%. Digital Subtraction Angiography (DSA) is gold standard. Identifies aneurysm location, size, and morphology for treatment planning.
Start nimodipine 60mg PO q4h immediately on SAH confirmation. Admit to NICU. Aneurysm treatment within 24–72h to prevent rebleed (rebleed risk 30% in first month, 50% in first year).
References — Thunderclap Headache
- Ottawa Rule Perry JJ et al. Sensitivity of computed tomography for SAH: 100%. BMJ 2011
- Mayo Clinic Thunderclap headache. mayoclinic.org
Raised Intracranial Pressure (ICP)
Classic Triad · Cushing's Reflex · Papilloedema · Herniation Syndromes
Normal ICP is 5–15 mmHg. Sustained ICP >20 mmHg requires treatment. Raised ICP is a common final pathway of many neurosurgical conditions: brain tumours, haematomas, hydrocephalus, cerebral oedema, hypertensive encephalopathy. Early recognition prevents irreversible brainstem damage from transtentorial herniation.
Progression of ICP Symptoms
Fixed dilated pupil + declining GCS = uncal herniation in progress. Give mannitol 1g/kg IV NOW + hyperventilate + emergency CT + prepare for emergency craniotomy. Every 15 minutes matters.
ICP Management Ladder
Improves venous drainage. Avoid neck flexion (compresses jugular veins). Simple, immediate, always first step.
Mannitol creates osmotic gradient drawing water out of brain. Use with serum osmolality <320 mOsm/kg. Hypertonic saline preferred for concurrent hypovolaemia.
Propofol/midazolam infusion. Target PaCO2 35–40mmHg (normocapnia). Temporary hyperventilation PaCO2 30–35 only for impending herniation.
4–10mg IV stat then 4mg QID. Highly effective for vasogenic oedema (tumour, abscess). NOT effective for cytotoxic oedema (stroke). CONTRAINDICATED in TBI (CRASH trial).
Bedside ICP monitoring + therapeutic CSF drainage. Target ICP <20mmHg and CPP >60mmHg. Gold standard for hydrocephalus-related ICP.
Remove the cause (haematoma, tumour) or decompressive craniectomy. Definitive treatment for surgical ICP elevation. Emergency craniotomy at BVH within 60 minutes of decision.
Focal Weakness & Hemiparesis
Upper vs Lower Motor Neuron · Stroke vs Mass Lesion · NIHSS Assessment
New-onset unilateral weakness affecting face, arm, or leg demands urgent neuroimaging. The differential includes ischaemic stroke, haemorrhagic stroke, subdural haematoma, brain tumour with surrounding oedema, brain abscess, demyelination (MS), and spinal cord compression. Time-critical distinction between stroke (thrombolysis window) and mass lesion (surgery) is essential.
Upper Motor Neuron (UMN) Signs — Brain or Cord
- Increased muscle tone (spasticity)
- Hyperreflexia (brisk deep tendon reflexes)
- Upgoing plantar (Babinski sign positive)
- Pyramidal pattern weakness: arm extensors, leg flexors
- No significant muscle wasting (initially)
Lower Motor Neuron (LMN) Signs — Cord / Root / Nerve
- Decreased / absent reflexes (hyporeflexia)
- Flaccid muscle tone
- Muscle wasting and fasciculations
- Myotomal distribution weakness
- Plantar normal or absent
Common Causes by Time Course
| Time Course | Likely Cause | Key Feature | Action |
|---|---|---|---|
| Seconds to minutes | Ischaemic Stroke, TIA | Vascular risk factors, AF, carotid disease | Emergency CT → tPA if <4.5h |
| Minutes to hours | Intracerebral Haemorrhage, SDH | Anticoagulants, trauma history, headache | Emergency CT + neurosurgery |
| Hours to days | Brain Tumour (apoplexy), Abscess | Prior symptoms, fever, immunosuppression | MRI with contrast urgently |
| Days to weeks | Brain Tumour, Chronic SDH, MS | Gradual progressive, other neurological signs | Urgent MRI + neurosurgical consult |
| Weeks to months | Low-grade Glioma, Meningioma | Slow progressive, seizures possible | MRI with contrast + planned neurosurgery |
Seizures & Epilepsy in Neurosurgical Context
First Seizure Workup · Status Epilepticus · Structural Causes · AED Selection
A single unprovoked seizure may be the first presentation of a brain tumour, cortical dysplasia, AVM, cavernoma, or abscess. All adults with a first seizure require brain MRI with contrast and EEG. Status epilepticus (>5 minutes of continuous seizure or repeated seizures without recovery) is a medical emergency with 20% mortality if untreated. The neurosurgeon's role: exclude structural causes and manage surgically remediable lesions.
Step 1 (0–5 min): Lorazepam 0.1mg/kg IV (max 4mg) OR diazepam 10mg IV. Step 2 (5–20 min): Levetiracetam 60mg/kg IV (max 4500mg) over 10 min OR valproate 40mg/kg IV. Step 3 (>20 min): Anaesthetic agents — propofol / midazolam infusion + ICU admission.
Structural Causes of New Seizures — Must Exclude
AED Selection — EEG-Guided (Dr. Wasif's Practice)
| EEG Pattern / Seizure Type | Preferred AED | Mechanism | Notes |
|---|---|---|---|
| Focal onset (frontotemporal spike) | Lacosamide (Lalap 50–200mg BD) | Sodium channel slow inactivation | Excellent tolerability; IV loading available |
| Focal — structural (tumour, AVM) | Levetiracetam (Levelanz 500–1500mg BD) | SV2A modulation | No CYP450 interactions; no monitoring |
| Generalised epilepsy (3Hz SW) | Valproate 400–1000mg BD | Broad spectrum (Na⁺, GABA) | Avoid in women of childbearing age |
| Drug-resistant focal epilepsy | Brivaracetam 50–200mg BD | SV2A (faster CNS penetration than LEV) | Better CNS penetration, fewer behavioural effects |
| AMPA receptor epilepsy / adjunct | Perampanel 2–12mg OD | AMPA antagonist | Adjunct for refractory focal + generalised |
| Dravet syndrome / refractory | Cannabidiol (Epidyolex) | Multiple (non-CB1/CB2) | Licensed for Dravet and LGS; specialist use |
| Dual MOA — all refractory focal | Cenobamate 100–400mg OD | Na⁺ channel + GABA-A PAM | Highest seizure-freedom rate in trials (21%) |
Back Pain Red Flags
NICE Red Flags · Cauda Equina Syndrome · Spinal Malignancy · Infection
95% of back pain is non-specific and self-limiting. However, approximately 1–5% of presentations have a serious underlying cause. Red flag symptoms identify this minority who require urgent investigation. The most critical neurosurgical emergency is cauda equina syndrome — requiring MRI and surgery within 24–48 hours to prevent permanent sphincter dysfunction.
NICE Red Flag Symptoms — Require Urgent Investigation
Ask in ALL patients with low back pain: "Any difficulty passing urine or controlling bowels? Any numbness around the genitals or inner thighs?" Even mild symptoms of bladder dysfunction with central disc herniation requires emergency MRI spine. Surgical decompression within 24h: 80% sphincter recovery. After 48h: 30% permanent dysfunction. After 72h: largely irreversible.
Visual Disturbances in Neurosurgery
Bitemporal Hemianopia · Papilloedema · Monocular Visual Loss · Diplopia
The visual pathway traverses critical neurosurgical territories — from retina through optic nerves, chiasm, tracts, lateral geniculate body, to occipital cortex. Specific visual field defects, combined with other signs, are highly localising for neurosurgical pathology.
| Visual Finding | Location of Lesion | Common Cause | Investigation |
|---|---|---|---|
| Monocular visual loss | Ipsilateral optic nerve | Optic neuritis, anterior ischaemic optic neuropathy, GCA | MRI orbits + ESR/CRP |
| Bitemporal hemianopia | Optic chiasm | Pituitary macroadenoma, craniopharyngioma, suprasellar meningioma | MRI pituitary + endocrine panel |
| Homonymous hemianopia | Optic tract or radiation or cortex | Stroke, brain tumour, AVM (occipital) | CT/MRI brain |
| Papilloedema (bilateral) | Raised ICP | Brain tumour, idiopathic intracranial hypertension, CVST, hydrocephalus | CT head → LP (if no mass) |
| 6th nerve palsy (diplopia) | False localising — raised ICP compresses CN VI | ICP from any cause; or direct clival lesion | Urgent CT head for ICP |
| 3rd nerve palsy + headache | CN III compression by posterior communicating artery aneurysm | PComA aneurysm (partial CN III = warning sign) | Emergency CTA/MRA for aneurysm |
A painful 3rd nerve palsy (ptosis + mydriasis + divergent eye) with headache is an aneurysm compressing CN III until proven otherwise. Emergency CTA. Risk of SAH within hours to days if not treated.
Paediatric Neurosurgical Warning Signs
Hydrocephalus · Posterior Fossa Tumours · Bulging Fontanelle · Shunt Malfunction
Symptom–Location Map
This anatomical guide helps clinicians and patients understand which symptoms correlate with which brain or spinal locations — invaluable for localisation and surgical planning.
- Personality change
- Expressive aphasia (Broca — dominant)
- Contralateral leg weakness (parasagittal)
- Frontal release signs
- Anosmia (olfactory groove)
- Complex partial seizures
- Memory impairment
- Receptive aphasia (Wernicke — dominant)
- Contralateral upper quadrant visual loss
- Temporal lobe personality
- Contralateral sensory loss
- Spatial neglect (non-dominant)
- Apraxia · Agnosia
- Gerstmann syndrome (dominant)
- Cortical sensory loss
- Ataxia (ipsilateral)
- Nystagmus · Dysarthria
- Cranial nerve palsies
- Obstructive hydrocephalus
- Truncal > limb ataxia (vermis)
- Ipsilateral CN palsy + contralateral motor
- Horner syndrome (descending sympathetics)
- Dysphagia · Dysarthria
- Respiratory irregularity
- Locked-in syndrome (basilar occlusion)
- C3–C5: Diaphragm (phrenic) — respiratory compromise
- C5–C6: Biceps, deltoid weakness
- T1: Hand intrinsics (Horner if T1 preganglionic)
- T10: Umbilicus sensory level
- L1–L2: Hip flexors; inguinal sensation
- S2–S4: Bladder, bowel, sexual function