Complications of Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a frightening and potentially life-threatening disorder in which blood ruptures from an artery in the brain and leaks into the cerebrospinal fluid (CSF).

Only about a third of patients with SAH have a “good result” after treatment. As if this wasn’t enough, subarachnoid hemorrhage can set off a cascade of other problems. To safeguard against these further complications, victims of subarachnoid hemorrhage are monitored in an intensive care unit after they first come into the hospital.

There are four major complications to subarachnoid hemorrhage. Those complications are vasospasm, hydrocephalus, seizures, and rebleeding.

Vasospasm After Subarachnoid Hemorrhage

The word vasospasm means that blood vessels in the brain “spasm” and clamp down, reducing and sometimes even stopping blood flow to parts of the brain. The result is a stroke.

Vasospasm usually occurs four to 14 days after the initial bleed.Because vasospasm is difficult to treat if it occurs, the emphasis of hospital care is prevention. The blood pressure medication nimodipine has been shown to reduce the likelihood of a poor outcome after vasospasm (though it does not seem to reduce the risk of developing vasospasm in the first place). Too little blood in the body has also been shown to correlate with vasospasm risk, and so the patient is given adequate fluids by IV to maintain blood volume at an even state (not too much, not too little). Other more experimental techniques for preventing vasospasm include giving statin medications.

People who have SAH are watched closely for signs of vasospasm with repeated neurological exams. If there’s a sudden worsening, it could mean vasospasm is occurring. Use of techniques like transcranial Doppler can also hint that someone is developing vasospasm.

In terms of treating vasospasm, the blood pressure is kept a bit high (induced hypertension) except for patients who have baseline hypertension or other heart problems that are a contraindication to this strategy.

If vasospasm persists in spite of hypertensive therapy, more invasive options, like angioplasty (opening the blood vessel with a catheter threaded through the blood vessels) or using a catheter to inject medications directly at the narrowed spot, may be attempted.

Hydrocephalus After Subarachnoid Hemorrhage

Sometimes a blood clot from the subarachnoid hemorrhage can become lodged in one of the important natural drainage sites of cerebrospinal fluid (CSF). Normally, CSF is produced in the ventricles of the brain. It then travels out through small openings known as foramina. If these openings are clogged, the CSF is still produced but has nowhere to go. The result is an increase in pressure inside the ventricles of the brain, which is known as hydrocephalus. The pressure spreads to the brain and skull.

Increased intracranial pressure can lead to decreased consciousness and coma. If left untreated, the brain can be pushed through tight regions like the opening at the base of the skull, resulting in death. To prevent this pressure build-up, neurosurgeons may place a shunt into the skull to drain out excess CSF. Lumbar drainage may also be used in the treatment of a type of hydrocephalus called communicating hydrocephalus. 

Seizure After Subarachnoid Hemorrhage

Blood can irritate the cerebral cortex and result in a seizure. However, only a small percentage of patients with SAH go on to have epilepsy (a seizure disorder). Doctors may consider using preventive anti-epileptics in the immediate period of time after the hemorrhage. But long-term anti-epileptic use is not recommended (with some exception based on individual risk factors), due to the risks of side effects.

Re-Bleeding After Subarachnoid Hemorrhage

After a SAH, the risk of re-bleeding is about 3 to 13 percent within the first 24 hours, according to a 2012 article in Stroke.Frequent neurological examinations and periodic head CT scans, especially in the period shortly after the initial bleed, can help detect re-bleed if it occurs.

To prevent re-bleeding, high-risk aneurysms in the brain are sealed off. This can be done by using a type of surgical staple to clip the aneurysm off from the rest of the artery, or by threading a catheter through the arteries up to the aneurysm and inserting metal coils or a sealant substance to seal the aneurysm. Which procedure is better is a complex decision that varies from person to person and requires a careful discussion with the medical team.

Bottom Line

While the four main complications of subarachnoid hemorrhage may seem like more than enough, unfortunately, there are several more potential dangers that come from having a serious enough illness to require care in an intensive care unit. Deep vein thrombosis of the legs, hyponatremia and hospital-acquired infections must also be guarded against. Surviving the initial bleed is only part of the challenge of subarachnoid hemorrhage. Surviving the rest will require close cooperation with a team of medical specialists.

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  3. Buczacki SJ, Kirkpatrick PJ, Seeley HM, Hutchinson PJ. Late epilepsy following open surgery for aneurysmal subarachnoid haemorrhage. J Neurol Neurosurg Psychiatry. 2004;75(11):1620-2. doi:10.1136/jnnp.2003.026856

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Additional Reading
  • Tidswell, P., et al. (1995). Cognitive outcome after aneurysm rupture: relationship to aneurysm site and perioperative complications. Neurology, 45:875.