Makindo Medical Notes

Related Subjects: |Brain tumour s |Astrocytomas |Brain Metastases |Tuberous sclerosis |Turcot's syndrome |Lhermitte Duclos Disease |Oligodendroglioma |Acute Hydrocephalus |Intracranial Hypertension |Primary CNS Lymphoma (PCNSL)

⚠️ A CT or MRI can appear normal in intracranial hypertension. An LP with measurement of opening pressure is required in suspected idiopathic intracranial hypertension (IIH), but never perform LP if there is suspicion of a mass lesion, obstructive hydrocephalus, or midline shift → risk of brain herniation.

📌 About

• CSF production ≈ 500 ml/day, absorbed by arachnoid villi into venous sinuses.
• Raised ICP occurs when production, flow, or absorption of CSF is impaired, or due to mass effect (tumour, haemorrhage, oedema).

🚫 When NOT to Perform LP

• Midline shift or herniation on imaging.
• Large mass lesion with oedema (tumour, abscess, haemorrhage).
• Obstructive hydrocephalus (ventricular block).

📷 When to Get Imaging Before LP

• Severe headache, sudden or progressive.
• Altered consciousness.
• Papilloedema.
• Focal neurological deficit (e.g. hemiparesis, aphasia).
• Seizures.
• Cushing’s triad: hypertension + bradycardia ± irregular breathing.

🧬 Aetiology

• Hydrocephalus: obstructive (non-communicating) vs impaired absorption (communicating).
• Head injury with cerebral oedema.
• Idiopathic Intracranial Hypertension (no mass lesion, pressure evenly distributed).
• Ischaemic stroke with malignant MCA syndrome.
• Cerebral venous sinus thrombosis.
• Colloid cyst obstructing 3rd ventricle.
• Intracranial haemorrhage (subdural, epidural, intracerebral).
• Brain tumours (primary or metastatic) ± oedema.
• Brain abscess and infections (meningitis, encephalitis).

🔎 Clinical Features

• Headache worse lying flat, relieved sitting/standing.
• Projectile vomiting (often without nausea).
• Transient visual loss when straining or bending.
• Papilloedema (though absence does not exclude raised ICP).
• Diplopia from VI nerve palsy (false localising sign).
• Oculomotor palsy (III) from uncal herniation.
• Sunset eyes in infants (upward gaze palsy).
• Coma: due to brainstem/reticular activating system dysfunction.

🧪 Investigations

• CT brain ± contrast.
• MRI ± gadolinium, MRV/CTV if venous thrombosis suspected.
• CT chest/abdomen/pelvis if malignancy/metastases suspected.
• LP only in IIH or if no evidence of pressure gradient/mass lesion.

⚠️ Complications

• Brain herniation → coma & death.
• Hydrocephalus.
• Persistent papilloedema → optic atrophy and blindness.

💊 Management

• Hydrocephalus → treat cause, ventriculoperitoneal shunt or ETV.
• Malignant MCA stroke → decompressive hemicraniectomy.
• Brain tumours → steroids (dexamethasone), debulking, radiotherapy.
• IIH → acetazolamide, weight loss, shunt if vision threatened.
• Haematoma → urgent neurosurgical evacuation.

📚 References

• Brain Journal – Intracranial Pressure Disorders
• NICE Guidelines – Head Injury & ICP Monitoring