Cerebral aneurysm
Besides from head injury, it may occur spontaneously, usually from a ruptured cerebral aneurysm (focal outpouchings with weakened walls on the arteries on the brain surface that are prone to rupture). Symptoms of SAH include a severe headache with a rapid onset (thunderclap headache), vomiting, confusion or a lowered level of consciousness, and sometimes seizures. CT scan has 100% sensitivity of detecting SAH at 6 to 24 hours after symptoms onset. The diagnosis is generally confirmed with a CT scan of the head. If CT scan is normal but SAH is still strongly suspected, lumbar puncture can be done at six to twelfth hours after the onset of headache. This is determine the presence of blood within the cerebrospinal fluid (CSF). Those with SAH will have blood and bilirubin within CSF because of degradation red blood cells. Meanwhile, those who has blood within CSF due to traumatic lumbar puncture will not have bilirubin within CSF. SAH is generally located within basal cisterns, extends diffusely to all subarachnoid spaces (cerebral sulci) or into the ventricular system, or brain parenchyma. Modified Fisher scale is used to describe the volume and distribution of SAH, just predicting the probability of cerebral artery vasospasm after SAH.Treatment is by prompt neurosurgery or radiologically guided interventions with medications and other treatments to help prevent recurrence of the bleeding and complications. Since the 1990s, many aneurysms are treated by a minimal invasive procedure known as endovascular coiling, which is carried out by instrumentation through large blood vessels.
It can cross the suture lines, but not across dural reflections such as falx cerebri or tentorium cerebelli. Therefore, subdural hematoma always limited to one side of the brain. Density of SDH reduces as it progresses from acute to chronic forms. However, areas with low density may not represent chronic SDH entirely as unclotted blood products that are due to active bleed can also give low density appearance on CT scans especially those with coagulopathy. Those with SDH that have same density with brain parenchyma may represent acute bleed such as those with anemia, arachnoid tear, and the mixing of hemorrhage and CSF. SDH usually have high or mixed densities during first two days of trauma, followed by isodensity at 11 days after trauma, and hypodensity after 14 days of trauma. Membranes with granulation tissue can rupture within SDH, and give high density appearance on CT scan. Over a prolonged period of time, calcifications can form. SDH can be treated with burr hole drainage, craniotomy or port system placement for blood clot evacuation, or middle meningeal artery embolisation.Subdural hematoma maybe less acute than epidural hematoma due to slower blood accumulation, but it still has the potential to cause brain herniation that may require surgical evacuation. Clinical features depend on the site of injury and severity of injury. Patients may have a history of loss of consciousness but they recover and do not relapse. Clinical onset occurs over hours.