Subarachnoid hemorrhage


Subarachnoid hemorrhage

Description, Causes and Risk Factors:

Abbreviation: SAH.

Subarachnoid hemorrhage (SAH) is usually the result of bleeding from an aneurysm in the Circle of Willis. The bleeding occurs in the arteries just below the arachnoid membrane and above the pia mater - just below the surface of the skull.

SAH may be spontaneous or traumatic. Spontaneous SAH are caused by cerebral aneurysms and AV malformations. The bleeding may occur spontaneously, typically from a ruptured cerebral aneurysm, or because of a head injury. An aneurysm is a bulge that develops in a blood vessel caused by a weakness in the blood vessel wall. As is the case with any stroke, a subarachnoid hemorrhage is a medical emergency - the risk of complications, brain damage and even death is considerable.

Traumatic subarachnoid hemorrhage is the most common cause of SAH overall. A large percentage of traumatic brain injuries involve some component of this type of bleeding.

Uncommon causes - neoplasms, dural AVM, venous angiomas, infectious aneurysms.

There's a slight tendency for the problem to run in families. Blood relations of someone who's had a subarachnoid hemorrhage have a 14% chance of having one, too. If you have two or more relatives affected, some experts recommend you have special screening tests of the blood vessels in your brain.

Smoking and excessive alcohol intake also increases the risk of getting SAH.

Subarachnoid hemorrhages make up about 5% of all strokes. Even though they are uncommon, they are responsible for approximately one quarter of all deaths caused by or related to strokes. Middle aged individuals and females are more likely to be affected.

Symptoms:

The main symptom is a severe headache that starts suddenly and is often worse near the back of the head. Patients often describe it as the "worst headache ever" and unlike any other type of headache pain. The headache may start after a popping or snapping feeling in the head.

    Sudden or decreased consciousness and alertness.

  • Difficulty or loss of movement or feeling.

  • Mood and personality changes, including confusion and irritability.

  • Muscle aches (especially neck pain and shoulder pain).

  • Nausea and vomiting.

  • Photophobia (light bothers or hurts the eyes).

  • Seizure.

  • Stiff neck.

  • Vision problems, including double vision, blind spots, or temporary vision loss in one eye.

Complications May Include:

    Hydrocephalus may develop within the first24 hours because of obstruction of CSFoutflow in the ventricular system by clottedblood.

  • Rebleeding of SAH occurs in 20% ofpatients in the first 2 weeks. Peak incidenceof rebleeding occurs the day after SAH.This may be from lysis of the aneurysmalclot.

  • Vasospasm from arterial smooth musclecontraction is symptomatic in 36% ofpatients.

  • Neurologic deficits from cerebral ischemia peak atdays 4-12.

  • Hypothalamic dysfunction causes excessivesympathetic stimulation, which may lead tomyocardial ischemia or labile detrimental BP.

  • Hyponatremia may result from cerebral salt wasting/ SIADH.

  • Nosocomial pneumonia and other complications ofcritical care may occur.

  • Pulmonary edema - neurogenic and nonneurogenic.

Diagnosis:

A physical exam may show a stiff neck due to irritation by blood of the meninges, the tissues that cover the brain. Except those in a deep coma, persons with a SAH may resist neck movement.A neurological exam may show signs of decreased nerve and brain function (focal neurologic deficit).

An eye exam will be performed. Decreased eye movements can be a sign of damage to the cranial nerves. In milder cases, no problems may be seen on an eye exam.

Arterial blood gases to exclude hypoxia.

If your doctor thinks you may have a SAH, a head CT scan (without dye contrast) should be immediately done. In some cases, the scan may be normal, especially if there has only been a small bleed. If the CT scan is normal, a lumbar puncture (spinal tap) must be performed. Patients with SAH will have blood in their spinal fluid.

CT scan angiography (using contrast dye) may be done to look for evidence of and aneurism.

Cerebral angiography of blood vessels of the brain is better than CT angiography to show small aneurysms or other vascular problems. This test can pinpoint the exact location of the bleed and can tell if there are blood vessel spasms.

Transcranial Doppler ultrasound is used to look at blood flow in the arteries of the brain that run inside the skull. The ultrasound beam is directed through the skull. It can also detect blood vessel spasms and may be used to guide treatment.

Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) are occasionally used to diagnose a SAH or find other associated conditions.

The Mini-Mental State Exam (MMSE) is generally considered a test of organic brain disease anddementia and has been used to test cognitive skills in patients who have had traumatic braininjury and stroke. It asks the patient to answer questions and perform tasks that evaluatescognitive skills such as attention, short-term or working memory and gross orientation. Thesemore subtle abnormalities are often the only deficits found with brain injury including SAH; and,they are likely to go unnoticed when mental status is assessed without using such standardizedtesting.

Treatment:

Identifying and treating the causative lesion, thus preventing re-bleeding.

Preventing cerebral vasospasm - to prevent blood vessels near the ruptured aneurysm from going into spasm, the patient may be given nimodipine for about three weeks. This medication is for hypertension (high blood pressure), but it also prevents spasms.

Headache - initially, because the pain is so severe, the patient may be given morphine. As symptoms improve the doctors may switch to other painkillers.

Neurosurgical clipping - this is a surgical intervention to seal the aneurysm shut with a small metal clip.

Endovascular coiling - a catheter or small plastic tube is inserted into an artery, usually in the patient's groin or leg, it is threaded through blood vessels until it reaches the part of the brain where the aneurysm is located. Platinum coils are pushed through the tube into the aneurysm and cut off the flow of blood into the aneurysm, effectively stopping the hemorrhage. This intervention has a higher success rate and the patient recovers more quickly, compared to neurological clipping.

Recovery from any type of stroke tends to be slow. Intensive rehabilitation therapy, including physiotherapy, speech therapy and occupational therapy are usually needed. Depression is a common problem after stroke, and good psychological and drug treatments are essential to help recovery.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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