Subarachnoid Hemorrhage: Four Leading Causes

A subarachnoid hemorrhage occurs when there is bleeding into the subarachnoid space that covers the brain and spinal cord. The four leading causes of these types of hemorrhages are aneurysms, arteriovenous malformation(AVM), hypertension and head trauma.

Leading causes for brain hemorrhages:

A brain hemorrhage or bleeding in the brain is a type of stroke. The most common non-traumatic cause of bleeding in the brain is a rupture of an aneurysm. An aneurysm is a balloon like bulge in an artery. Aneurysms can be the result of congenital abnormalities and present no symptoms until they bleed.

A brain arteriovenous malformation (AVM) is an abnormal connection between the arteries and veins and generally these develop before birth. Sometimes symptoms are mild with only headaches and at times there are no symptoms until bleeding occurs. Other times patients experience seizures, pulsating buzzing in their head, or progressive weakness from the AVM.

Hypertension is another leading cause of brain hemorrhages because it can weaken blood vessel walls over time and this makes them susceptible to rupture. Drug abuse, frequently an occupational hazard of the rock and roll lifestyle, especially cocaine and amphetamines, can also cause artery walls to inflame and weaken. Smoking is another risk factor for this type of stroke. It is unclear if Michaels was either a heavy smoker or drug abuser.

Traumatic injury to the brain can cause blood clots on the surface of the brain or within the brain.

Cerebral aneurysm (brain artery dilation)

An abnormal widening or ballooning of an artery in the brain. Most are congenital and do not cause symptoms until they leak blood or burst and bleed profusely. Rarely the dilation of the vessel can be large enough to cause symptoms before they leak by pressing on surrounding brain. The most common initial symptom is a sudden severe headache.Reviewed by Harvard Medical SchoolSymptomsThe symptoms depend on the amount of bleeding. A small amount of bleeding (sentinel bleed) causes a sudden severe headache (thunder clap headache), and vomiting. More significant bleeding can cause: confusion, fainting, weakness, seizures, coma and death. If the aneurysm has not bled but is large enough to cause symptoms then one may see: progressively worse headache, vomiting, confusion, change in behavior, weakness, visual problems, seizures.Reviewed by Harvard Medical SchoolTestsWorkupA history and physical exam will be performed. If the doctor suspects an aneurysm a head CT or brain MRI will be done. The addition of contrast may help identify the disorder (CT angiogram or MR angiogram). Sometimes a lumbar puncture is performed to identify the blood in the cerebrospinal fluid when an imaging study has been negative and the suspicion is still high for a ruptured aneurysm.TestsComplete blood count (CBC), CT Scan and MRIAdditional tests that may be requiredLumbar puncture, CTA, MRA

SpecialistsNeurosurgery and Pediatric NeurosurgeryReviewed by Harvard Medical SchoolTreatmentTherapy depends on the amount of bleeding. Severe bleeding may require: insertion of a breathing tube, anti-seizure medication, blood pressure medication, and/or surgery. The goal of unruptured aneurysms that don't cause symptoms depends on the size and location. Observation and periodic repeat imaging may be advised. Or treatment to prevent rupture or reduce symptoms may include: surgical clipping or endovascular embolization.