Subarachnoid hemorrhage

Subarachnoid hemorrhage
Other namesSubarachnoid haemorrhage
CT scan of the brain showing subarachnoid hemorrhage as a white area in the center (marked by the arrow) and stretching into the sulci to either side
Pronunciation
SpecialtyNeurosurgery, Neurology
SymptomsSevere headache of rapid onset, vomiting, decreased level of consciousness[1]
ComplicationsDelayed cerebral ischemia, cerebral vasospasm, seizures[1]
TypesTraumatic, spontaneous (aneurysmal, nonaneurysmal, perimesencephalic)[1]
CausesHead injury, cerebral aneurysm[1]
Risk factorsHigh blood pressure, smoking, alcoholism, cocaine[1]
Diagnostic methodCT scan, lumbar puncture[2]
Differential diagnosisMeningitis, migraine, cerebral venous sinus thrombosis[3]
TreatmentNeurosurgery or radiologically guided interventions[1]
MedicationLabetalol, nimodipine[1]
Prognosis45% risk of death at 30 days (aneurysmal)[1]
Frequency1 per 10,000 per year[1]

Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain.[1] Symptoms may include a severe headache of rapid onset, vomiting, decreased level of consciousness, fever, weakness, numbness, and sometimes seizures.[1] Neck stiffness or neck pain are also relatively common.[2] In about a quarter of people a small bleed with resolving symptoms occurs within a month of a larger bleed.[1]

SAH may occur as a result of a head injury or spontaneously, usually from a ruptured cerebral aneurysm.[1] Risk factors for spontaneous cases include high blood pressure, smoking, family history, alcoholism, and cocaine use.[1] Generally, the diagnosis can be determined by a CT scan of the head if done within six hours of symptom onset.[2] Occasionally, a lumbar puncture is also required.[2] After confirmation further tests are usually performed to determine the underlying cause.[2]

Treatment is by prompt neurosurgery or endovascular coiling.[1] Medications such as labetalol may be required to lower the blood pressure until repair can occur.[1] Efforts to treat fevers are also recommended.[1] Nimodipine, a calcium channel blocker, is frequently used to prevent vasospasm.[1] The routine use of medications to prevent further seizures is of unclear benefit.[1] Nearly half of people with a SAH due to an underlying aneurysm die within 30 days and about a third who survive have ongoing problems.[1] Between ten and fifteen percent die before reaching a hospital.[4]

Spontaneous SAH occurs in about one per 10,000 people per year.[1] Females are more commonly affected than males.[1] While it becomes more common with age, about 50% of people present under 55 years old.[4] It is a form of stroke and comprises about 5 percent of all strokes.[4] Surgery for aneurysms was introduced in the 1930s.[5] Since the 1990s many aneurysms are treated by a less invasive procedure called endovascular coiling, which is carried out through a large blood vessel.[6]

A true subarachnoid hemorrhage may be confused with a pseudosubarachnoid hemorrhage, an apparent increased attenuation on CT scans within the basal cisterns that mimics a true subarachnoid hemorrhage.[7] This occurs in cases of severe cerebral edema, such as by cerebral hypoxia. It may also occur due to intrathecally administered contrast material,[8] leakage of high-dose intravenous contrast material into the subarachnoid spaces, or in patients with cerebral venous sinus thrombosis, severe meningitis, leptomeningeal carcinomatosis,[9] intracranial hypotension, cerebellar infarctions, or bilateral subdural hematomas.[10]

  1. ^ a b c d e f g h i j k l m n o p q r s t u v Abraham MK, Chang WW (November 2016). "Subarachnoid Hemorrhage". Emergency Medicine Clinics of North America. 34 (4): 901–916. doi:10.1016/j.emc.2016.06.011. PMID 27741994.
  2. ^ a b c d e Carpenter CR, Hussain AM, Ward MJ, Zipfel GJ, Fowler S, Pines JM, Sivilotti ML (September 2016). "Spontaneous Subarachnoid Hemorrhage: A Systematic Review and Meta-analysis Describing the Diagnostic Accuracy of History, Physical Examination, Imaging, and Lumbar Puncture With an Exploration of Test Thresholds". Academic Emergency Medicine. 23 (9): 963–1003. doi:10.1111/acem.12984. PMC 5018921. PMID 27306497.
  3. ^ Cite error: The named reference Ox2007 was invoked but never defined (see the help page).
  4. ^ a b c van Gijn J, Kerr RS, Rinkel GJ (January 2007). "Subarachnoid haemorrhage". Lancet. 369 (9558): 306–18. doi:10.1016/S0140-6736(07)60153-6. PMID 17258671. S2CID 29126514.
  5. ^ Todd NV, Howie JE, Miller JD (June 1990). "Norman Dott's contribution to aneurysm surgery". Journal of Neurology, Neurosurgery, and Psychiatry. 53 (6): 455–8. doi:10.1136/jnnp.53.6.455. PMC 1014202. PMID 2199609.
  6. ^ Strother CM (May 2001). "Historical perspective. Electrothrombosis of saccular aneurysms via endovascular approach: part 1 and part 2". AJNR. American Journal of Neuroradiology. 22 (5): 1010–2. PMID 11337350. Archived from the original on 14 November 2005.
  7. ^ Dixon A. "Pseudosubarachnoid hemorrhage | Radiology Reference Article | Radiopaedia.org". Radiopaedia.
  8. ^ Given CA, Burdette JH, Elster AD, Williams DW (1 February 2003). "Pseudo-Subarachnoid Hemorrhage: A Potential Imaging Pitfall Associated with Diffuse Cerebral Edema". AJNR. American Journal of Neuroradiology. 24 (2): 254–256. PMC 7974121. PMID 12591643.
  9. ^ Marder CP, Narla V, Fink JR, Tozer Fink KR (26 December 2013). "Subarachnoid Hemorrhage: Beyond Aneurysms". American Journal of Roentgenology. 202 (1): 25–37. doi:10.2214/AJR.12.9749. PMID 24370126.
  10. ^ Coulier B (1 March 2018). "Pseudo-subarachnoid Hemorrhage". Journal of the Belgian Society of Radiology. 102 (1): 32. doi:10.5334/jbsr.1509. PMC 6032606. PMID 30039044.