- MC traumatic hemorrhage (SAH > SDH)
- Site of bleeding: Subarachnoid space (between arachnoid & pia)
- MC cause of spontaneous (non-traumatic) SAH: Rupture of Berry’s aneurysm
- The defect in berry aneurysm is: Degeneration of tunica media (Muscle layer).
- MC site of Berry’s aneurysm: Between Anterior cerebral artery & Anterior communicating artery (absent internal elastic lamina and muscle)
- LC site of Berry’s aneurysm/ Aneurysm most likely to rupture: Bifurcation of basilar artery (into Posterior cerebral artery)/ Vertebrobasilar junction
- MC-ly involved cranial nerve in Berry’s aneurysm: CN-III
- Special note: MCA does not take part in formation of Circle of Willis.
- “Thunder clap headache”/ “Worst headache of life”
- Neck rigidity.
- IOC/ Screening investigation of acute SAH: NCCT
- IOC for cerebral aneurysm in a patient with SAH: CT angiography
- Best investigation for cerebral aneurysm: DSA (Digital subtraction angiography), as it gives bone free image
- Lumbar puncture:
Xanthochromia (Xanthos – Yellow; Chroma – Color) in CSF is highly suggestive of subarachnoid hemorrhage. The colour is due to the hemoglobin degradation products.
- MC cause of death in SAH due to Berry aneurysm is: Vasospasm → Cerebral ischemia
- Cerebral salt wasting syndrome (CSW): Hypovolemic hyponatremia caused by release of BNP (causing natriuresis) from brain in response to increased ICT.
Differentiating CSW from SIADH:
- In both cases, hyponatremia and high urine osmolarity are present
- But in CSW, clear evidence of volume depletion (i.e. hypotension, decreased skin turgor, elevated hematocrit) is evident
- By comparison, extracellular fluid volume is normal or slightly increased with SIADH.
- Medical management by Nimodipine (intracerebrally acting CCB) given for 21 days
- Intervention to prevent rebleed: Endovascular coiling
- Intervention in wide mouth aneurysm: Craniotomy + Clipping
- Coiling is preferred over clipping
- Platinum based coil is used.
Related topic: Normal MR angio landmarks of neck: