| Figure 2.
| Figure 3.
The diagnosis of spontaneous subarachnoid hemorrhage (SAH) was made based on the hyperdensity seen in the subarachnoid space on the noncontrast-enhanced cerebral CT scan (Figure 2). Once the CT diagnosis was made, the other diagnoses in the differential above were effectively ruled out, as the likelihood of 2 simultaneous processes is very low. The history did not reveal significant head trauma, so it was concluded that this was a spontaneous (nontraumatic) SAH. After making the diagnosis and controlling the patient’s pain, urgent neurosurgical consultation was obtained.
Spontaneous SAH is a neurosurgical emergency and a life-threatening condition. It can progress to coma, permanent brain damage, and death. It is characterized by extravasation of blood into the subarachnoid space, most commonly from a berry aneurysm or other vascular malformation. The incidence of subarachnoid hemorrhage is 2-49 cases per 100,000 people per year internationally, and 10%-15% of patients die before reaching the hospital. People of African heritage are at higher risk than whites by a ratio of 2.1 to 1. Asians are also at higher risk, and the incidence of subarachnoid hemorrhage is higher in women. Other risk factors include polycystic kidney disease, lupus, Ehlers-Danlos syndrome, and tobacco use. The mean age of onset is 50 years.
The typical presentation of a nontraumatic SAH is marked by the sudden onset of a severe headache, which has been dubbed “thunderclap headache. The rapid onset of the headache is the most important historical feature. Patients usually refer to an SAH as the worst headache of their life; however, patients presenting to an ED with headache of any etiology will often have the same complaint. Headache from SAH tends to be occipital in location. In patients with a prior history of cephalgia, headache from SAH is usually, but not always, described as different from prior headaches. Sentinel headaches are SAHs that do not cause catastrophic damage. If recognized, a sentinel headache provides an opportunity for intervention before a larger, more debilitating SAH occurs. Patients may also experience epileptic seizures, nausea or vomiting, neck stiffness, photophobia, and loss of consciousness. On physical examination, neurologic and vital-sign abnormalities may be present; these include cranial nerve signs, motor deficits, seizures, coma, ophthalmologic signs (papilledema, retinal hemorrhage), and mild-to-moderate blood pressure elevation. A history of headache prior to a fall or syncopal episode or an uncertain history of trauma should increase suspicion for spontaneous SAH.
The severity of an SAH is most commonly graded using the Hunt-Hess scale, as follows:
- 0: Unruptured aneurysm
- 1: Asymptomatic or minimal headache without neck rigidity
- 2: Moderate-to-severe headache, neck rigidity, cranial nerve palsy
- 3: Drowsy, confused, mild focal deficit
- 4: Stupor, moderate-to-severe deficit, hemiparesis
- 5: Deep coma, decerebrate rigidity, moribund
The differential diagnosis of SAH is very large. It includes encephalitis, meningitis, primary headaches (migraine, cluster headache), temporal arteritis, hypertensive encephalopathy, spontaneous intracerebral hemorrhage, ischemic stroke, transient ischemic attack, panic attack, craniocervical dissections, and cerebral venous sinus thrombosis, as well as other causes of headache.
The most useful initial diagnostic tool to confirm the diagnosis of SAH is a noncontrast brain CT scan, which shows the hyperdense collection of blood in the subarachnoid space. The sensitivity of CT scanning of the brain is considered to be 90%-95% within 24 hours of symptom onset, 80% at 3 days, and 50% at 1 week. In a recent study, high-resolution CT scanning was positive for SAH in all cases examined within 12 hours from the onset and in 93% of patients who presented within 24 hours of onset. Brain CT scan is also useful because it may demonstrate associated complications of SAH, such as hydrocephalus, ischemic strokes due to vasospasm, mass effect, and signs of impending herniation. A falsely negative CT scan may result if there is only a very small sentinel bleed. These patients will usually be Hunt-Hess grade 1, and they are also the patients with the best prognosis if they are diagnosed and treated before a catastrophic SAH. Other possible causes of a false-negative CT scan include a delay of more than 12 hours from symptom onset, anemia (with a hemoglobin < 10 g/dL), and movement artifacts. The clinician should always ask the radiologist if a careful review for blood in the interpeduncular cistern was performed. This area sits just posterior and thus dependent on the circle of Willis and, therefore, forms a natural “cup” that may collect just enough blood to be seen on CT when an SAH is very small.
The gold standard diagnostic test for SAH is a lumbar puncture (LP) with cerebrospinal fluid (CSF) analysis. An LP must be performed after a negative brain CT scan whenever there is a suspicion of SAH and no contraindications to the procedure. As opposed to CT scanning, the sensitivity of lumbar puncture for SAH initially improves as the time from onset increases. In addition, an important alternate diagnosis, such as meningitis or encephalitis, may be made. The most important CSF findings in SAH are consistently elevated red blood cell counts in 2 or more tubes, as well as xanthochromia, which is seen by 12 hours after the onset of bleeding. The opening pressure should be measured, as it is often elevated in cases of SAH. A false-negative LP may occur if the procedure is done too early, before enough time has elapsed for blood from the brain to circulate down into the lumbar area. Although it is not recommended that LP be delayed because of this reason, it is important to know that sensitivity decreases if the LP is performed before 12 hours from symptom onset. Fortunately, this is exactly the time frame in which the CT scan is most sensitive. In addition, LP loses sensitivity after 2 weeks from symptom onset.
Once the diagnosis of SAH has been confirmed either by CT or LP, medical stabilization should be instituted. This is followed by an urgent examination of the intracerebral blood vessel anatomy for early visualization of the bleeding source (if it exists), which most often is a berry aneurysm or arteriovenous malformation (AVM). Medical stabilization is aimed at preventing early complications, including brain edema, hydrocephalus, and rebleeding, as well as the late complication of vasospasm. Treatment options include bed rest with elevation of the head of the bed to 30 degrees, nimodipine (a calcium channel blocker to prevent vasospasm), seizure prophylaxis, antiemetics, analgesia, and labetalol or other agents as needed for blood pressure control.
Vascular malformations leading to SAH can be identified by conventional cerebral angiography, CT angiography, or by magnetic resonance angiography of the cerebral vasculature. Other indications for one of these tests would be if LP is not possible or is refused by the patient or if the work-up is negative but more than 2 weeks since symptom onset have passed. Some experts also recommend angiography in certain high-risk patients despite a negative CT and LP, such as those with polycystic kidney disease, Marfan syndrome, a family history of SAH, or suspicion for vascular dissection. The clinician should not recommend angiography in lieu of LP, however, because it is neither extremely sensitive nor specific for the diagnosis of SAH. Angiography is only 80%-90% sensitive for SAH. In addition, approximately 1%-2% of the population has an asymptomatic berry aneurysm. Unless they are large or have bled, these aneurysms do not require treatment. Making the diagnosis of berry aneurysm without an LP showing an SAH may lead to confusion about the best course of action or even to unnecessary surgery.
Digital-subtraction cerebral angiography is invasive, but it has a great sensitivity for showing vascular anatomy and current bleeding site, and to visualize other aneurysms or AVMs. Magnetic resonance angiography is noninvasive, but it has lower sensitivity for visualization of the intracerebral vessels, requires more time to perform the examination, has a greater risk of movement artifacts, and is more examiner-dependent. CT angiography has a similar sensitivity but exposes the patient to a greater dose of radiation and is also examiner-dependent. In 10%-20% of patients with SAH, there is no evident source of bleeding after imaging assessment of the cerebral vessels (nonaneurysmal SAH). The outcome of nonaneurysmal SAH is better than that of aneurysm rupture or AVM. Depending on the localization of the subarachnoid blood, there are 2 nonaneurysmal SAH patterns that mimic true aneurysmal rupture: perimesencephalic hemorrhage and “aneurysmal hemorrhage pattern. When angiography is positive, early neurosurgical intervention with clipping, coiling, or glue injection into the vascular malformation improves the outcome of patients and decreases the risk of rebleeding (a major complication of SAH).
The patient in this case was diagnosed with a Hunt-Hess Scale grade 2 SAH based on her severe headache and the nuchal rigidity found on the physical examination. She was referred to the neurosurgical department after the CT scan results were evaluated. Urgent cerebral angiography was performed, which was negative for intracerebral aneurysm or AVM. Magnetic resonance angiography was performed the next day and was also negative. The patient remained in the neurosurgical department for close observation. She received intravenous fluids, nimodipine, analgesics, and laxatives. She was monitored for cerebral vasospasm by transcranial Doppler sonography and was kept on bed rest for the first 10 days of her admission, with progressive active mobilization thereafter. She developed mild, subclinical vasospasm on day 5 of hospitalization, which resolved completely afterward. She was transferred to the neurologic department for further conservative treatment on day 9 and discharged from the hospital on day 17. Her clinical condition improved continuously during her admission, with resolution of her headache, nuchal rigidity, and miosis and with no development of other neurologic signs during her observation. A CT scan performed 1 month later (Figure 3) showed complete absorption of the blood from the subarachnoid space, with no sign of hydrocephalus or other complications. At discharge, sexual abstinence was recommended for 6 weeks in order to decrease the chance of rebleeding. She was also counseled to avoid strenuous activity for the first 6 weeks after her discharge from the hospital. After 3 months, the patient’s clinical condition remained excellent.