Response to Letter Regarding Article, “Time-Dependent Test Characteristics of Head CT in Patients Suspected of Nontraumatic Subarachnoid Hemorrhage”
We thank Dr Yeo and coworkers for their interest in our study, in which we concluded that in patients presenting with acute headache and a normal head CT ≤6 hours after ictus, there is no added value of cerebrospinal fluid analysis.1
Dr Yeo and coworkers warn that our results need to be interpreted with caution. We cannot agree more, and that is why we emphasized (as Yeo et al do) that our results only can be extrapolated to high-volume tertiary care centers where head CT scans are interpreted by experienced neuroradiologists.1 However, Yeo et al end with the recommendation that in patients with acute headache but a negative early CT scan, a lumbar puncture should still be performed and perhaps even combined with a CT angiography. They illustrate their recommendation with a patient with severe frontal headache of sudden onset, nausea, vomiting, photophobia, and neck stiffness. An initial noncontrast CT scan performed at 2 hours after symptom onset was unremarkable. Fourteen hours later, this patient had a generalized tonic–clonic seizure. A subsequent head CT showed subarachnoid hemorrhage (SAH) extending to the ventricles.
We would like to make 3 comments on this patient and the conclusion the authors draw. First, unfortunately the authors do not show the initial scan. It is well known that in patients with SAH, head CT can show only subtle signs of bleeding. A well-known pitfall in the interpretation of head CT in patients with SAH is isolated blood in the interhemispheric fissure or interpeduncular cistern. Therefore, we stress in our article that our recommendation only applies if the CT scan is interpreted by an experienced neuroradiologist working in a center with a high volume of patients with SAH. Second, the authors make the assumption that if a lumbar puncture had been performed, it had shown signs of SAH. This assumption might very well be erroneous. The patient might have been one of the rare patients who have an intracranial intramural dissection causing acute headache but without hemorrhage and a few hours later extension into a transmural section provoking SAH. Without the proof of a positive cerebrospinal fluid examination in this patient, the authors can in our view not conclude that a lumbar puncture would have been helpful in this patient. Third, the patient was described to have neck stiffness. Because a patient with neck stiffness has not a normal neurological examination, the treating physician should not be reluctant to question the interpretation of head CT by the radiologist. We urge further examinations in patients with neck stiffness to diagnose the cause. In our view, lumbar puncture should have been performed anyway in this patient.
We cannot disagree more with the suggestion that a CT angiography might help in reducing mortality and long-term disability in patients with acute headache and a negative CT. This approach will also result in the detection of asymptomatic and often very small aneurysms that may need follow-up over time instead of being treated. The detection of asymptomatic aneurysms has a considerable impact on quality of life.2 In patients with acute headache, it is pivotal to first rule in or out a SAH. Further examinations to find an aneurysm or other cause of the SAH should be performed only in patients with a proven SAH.
Daan Backes, MD
Gabriel J. E. Rinkel, MD
Mervyn D. I. Vergouwen, MD, PhD
UMC Utrecht Stroke Center
Department of Neurology and Neurosurgery
Rudolf Magnus Institute of Neuroscience
University Medical Center Utrecht
Utrecht, the Netherlands
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- © 2012 American Heart Association, Inc.
- Backes D,
- Rinkel GJ,
- Kemperman H,
- Linn FH,
- Vergouwen MD
- Wermer MJ,
- van der Schaaf IC,
- Van Nunen P,
- Bossuyt PM,
- Anderson CS,
- Rinkel GJ