Correspondence
Making the Diagnosis of Subarachnoid Hemorrhage
N Engl J Med 2000; 342:1454-1456May 11, 2000
- Article
To the Editor:
Edlow and Caplan (Jan. 6 issue)1 present an excellent review of the pitfalls encountered in the diagnosis of subarachnoid hemorrhage. However, after stating that the initial diagnostic study should be noncontrast computed tomography (CT) of the head, the authors suggest that lumbar puncture might be an acceptable initial diagnostic procedure in patients with normal findings on physical examination. We recommend continuing the practice of obtaining a CT scan in all cases of suspected subarachnoid hemorrhage, before performing a lumbar puncture, regardless of the findings on the neurologic examination. A CT scan showing the presence of subarachnoid blood establishes the diagnosis and precludes the need for a lumbar puncture, which might precipitate rebleeding from a ruptured aneurysm. A decrease in intracranial pressure as a result of drainage of spinal fluid or an increase in systemic blood pressure induced by procedure-related catecholamine release may cause a sufficient pressure gradient to precipitate further hemorrhage, with catastrophic consequences. CT scanning will also reveal any unsuspected intracranial lesions with mass effect that might preclude a safe lumbar puncture.
The authors also raise the issue of “traumatic taps” that lead to the diagnosis of an incidental aneurysm and precipitate “potentially risky diagnostic and therapeutic interventions.” Despite the results of the International Study of Unruptured Intracranial Aneurysms,2 the best population-based studies suggest that the annual risk of rupture of intracranial aneurysms is between 1.4 percent and 2.3 percent, regardless of the size of the aneurysm.3,4 In one of these studies, the mortality rate associated with rupture was 52 percent.3 Assuming a 2 percent annual risk of rupture and a 50 percent mortality rate, a patient with a life expectancy of 30 years has a 55 percent cumulative risk of rupture and a 27 percent cumulative risk of death.5 An unruptured aneurysm detected because of a traumatic tap should not be managed in the same manner as a ruptured aneurysm. However, treatment of incidental aneurysms can be lifesaving.
5 ReferencesRichard E. Clatterbuck, M.D., Ph.D.
Rafael Tamargo, M.D.
Daniele Rigamonti, M.D.
Johns Hopkins Hospital, Baltimore, MD 212871
Edlow JA ,Caplan LR . Avoiding pitfalls in the diagnosis of subarachnoid hemorrhage. N Engl J Med 2000;342:29-36
Full Text | Web of Science | Medline2
The International Study of Unruptured Intracranial Aneurysms Investigators
Full Text | Web of Science | Medline3
Juvela S ,Porras M ,Heiskanen O . Natural history of unruptured intracranial aneurysms: a long-term follow-up study. J Neurosurg 1993;79:174-182
CrossRef | Web of Science | Medline4
Yasui N ,Suzuki A ,Nishimura H ,Suzuki K ,Abe T . Long-term follow-up study of unruptured intracranial aneurysms. Neurosurgery 1997;40:1155-1160
CrossRef | Web of Science | Medline5
Tamargo RJ ,Walter KA ,Oshiro EM . Aneurysmal subarachnoid hemorrhage: prognostic features and outcomes. New Horiz 1997;5:364-375
Medline
To the Editor:
Edlow and Caplan mention the problem of diagnostic ambiguity in patients with subarachnoid hemorrhage who also sustain head injuries. As Sakas et al. have reported,1 abrupt falls and head trauma after loss of consciousness due to spontaneous subarachnoid hemorrhage are not rare. Identifying the true nature of subarachnoid hemorrhage (aneurysmal or traumatic) can be difficult, as is illustrated by our recent experience with two patients.
The first patient was a 25-year-old woman who presented to the emergency room with a closed head injury due to an assault. She reported no loss of consciousness. On neurologic examination she was sleepy but easily arousable, without any deficits. She had bilateral periorbital ecchymoses and a nasal fracture. A CT scan showed subarachnoid hemorrhage in the basilar and supracellar cisterns and left sylvian fissure. Because the CT images were more suggestive of an aneurysmal subarachnoid hemorrhage than of a traumatic one, an angiogram was obtained. It showed an aneurysm of the middle cerebral artery at its bifurcation. An acutely ruptured aneurysm was successfully clipped. The patient had an uneventful postoperative course.
A second patient was a 43-year-old woman who was admitted to the emergency room because of a headache, which developed after a piece of concrete from an unrepaired ceiling in her home had fallen on her head. She reported no previous headache. Neurologic examination showed no abnormalities. A CT scan showed subarachnoid hemorrhage within the anterior interhemispheric fissure, the supracellar cistern, and both sylvian fissures. A magnetic resonance angiogram showed an anterior communicating aneurysm. Four-vessel angiographic studies confirmed the diagnosis. The recently ruptured aneurysm was clipped without difficulty. The patient's postoperative course was uneventful.
In both cases, head trauma clearly preceded the onset of headache. The warning sign for us was the appearance of subarachnoid hemorrhage on CT scans. Focal subarachnoid hemorrhage within the basal cisterns or the interhemispheric or sylvian fissure, or both, was more consistent with the presence of an aneurysmal subarachnoid hemorrhage than with the presence of a traumatic subarachnoid hemorrhage. We would like to highlight the importance of CT findings in such cases. Patients with clear histories of traumatic head injury should be evaluated with CT studies when appropriate. The character and distribution of any subarachnoid blood should be carefully assessed. If the distribution of the hemorrhage is consistent with an aneurysmal rather than a traumatic source, an angiogram, a magnetic resonance angiogram, or both should be obtained.
1 ReferencesOguz Cataltepe, M.D.
St. Luke's–Roosevelt Hospital, New York, NY 10019David Langer, M.D.
Eugene Flamm, M.D.
Beth Israel University Hospital, New York, NY 101281
Sakas DE ,Dias LS ,Beale D . Subarachnoid haemorrhage presenting as head injury. BMJ 1995;310:1186-1187
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Author/Editor Response
The authors reply:
To the Editor: Under optimal circumstances, we recommend noncontrast CT scanning as the first diagnostic study in evaluating patients for subarachnoid hemorrhage. CT scanning is fast, safe, painless, inexpensive, noninvasive, and widely available. A positive finding precludes the need for lumbar puncture. A CT scan may also reveal other, unsuspected central nervous system abnormalities, provide information about the location of the aneurysm that has ruptured in patients with multiple aneurysms, and identify treatable complications, such as hematoma and hydrocephalus.
The safety of a strategy of performing lumbar puncture first in carefully selected patients (which is postulated to be cost effective)1 has not been studied clinically. If this approach is used, it is critical that it be limited to patients with acute headache and completely normal findings on physical examination, including normal vital signs, a normal level of consciousness, the absence of abnormalities on neurologic examination, and the absence of neck stiffness.
A discussion of the treatment of patients with unruptured aneurysms was beyond the scope of our article, but we agree with Dr. Clatterbuck and colleagues that an incidental unruptured aneurysm discovered because of a traumatic tap should not be treated in the same manner as a ruptured aneurysm.
Dr. Cataltepe and colleagues present two interesting cases that are variations on the theme of missed aneurysmal hemorrhages. Whether the association between the head trauma and the aneurysmal rupture was coincidental or causal is impossible to know. We agree that the pattern of subarachnoid blood on the CT scan can be a useful clue in treating patients who present with head injury. These two cases also highlight the importance of paying attention to all the details in evaluating patients with headache.
1 ReferencesJonathan A. Edlow, M.D.
Louis R. Caplan, M.D.
Beth Israel Deaconess Medical Center, Boston, MA 022151
Schull MJ . Lumbar puncture first: an alternative model for the investigation of lone acute sudden headache. Acad Emerg Med 1999;6:131-136
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