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Patient outcomes vs a minimally invasive approach in lumbar spinal stenosis: which is more important?

To the Editor: The cerebral vasospasm is one of the most important cause of morbidity and mortality in spontaneous subarachnoid hemorrhage (SAH). Recent medical literature has brought many concepts and debates about symptomatic vasospasm, vasospasm in transcranial Doppler (TCD), angiographic vasospasm, and the possibilities of early diagnosis. In a recent study, Carrera et al analyzed 441 of 695 patients admitted to Columbia University Medical Center with SAH between July 1996 and April 2003. The study was well designed and revealed that the increased flow velocity (mBFV) slightly increased the risk of delayed cerebral ischemia (DCI), revealing that mBFV values greater than 120 cm/s had a sensitivity of only 62% and value PPV of 22% for the diagnosis of DCI. Two important limitations of the study already cited by the author in Neurosurgery. One is the absence of the use of the index Lindengaard and other application sporadic of TCD (not performed daily in all patients). Another weakness of the study is that it does not describe it was measured and compared the mBVF of both brain hemispheres in the same patient. It is known that various causes such as anemia, hyperemia, hypercapnia, increased intracranial pressure and infection can increase mBFV therefore should be relevant mBFV comparison between the two cerebral hemispheres in order to minimize a possible bias. This is a very interesting study on a topic that is still controversial, vasospasm and its predictors, and bring a great relevant enrichment for literature.