Eur Radiol (2002) 12:2610 DOI 10.1007/s00330-002-1510-3

T. Duprez

Received: 15 March 2002 Accepted: 16 April 2002 Published online: 21 June 2002 © Springer-Verlag 2002 This reply refers to the Letter to the Editor at http://dx.doi.org/10.1007/s00330-0021508-x and at http://dx.doi.org/10.1007/s00330-0021509-9

T. Duprez (✉) Département de Radiologie et d’Imagerie, U.C.L. Clinique Universitaires Saint-Luc, Avenue Hippocrate 10, 1200 Brussels, Belgium e-mail: [email protected] Tel.: +32-2-7642951

LETTER TO THE EDITOR

Reply Sir, The letter of U. Salvolini and A. Messori, and that of A. Guermazi, on the MR features of SIH highlight the growing interest of the radiological community in a better recognized clinical–radiological condition which may have been underestimated before the era of MRI. However, diagnosing the condition still remains challenging, and both comments point out majors issues when dealing with SIH in clinical practice: 1. Increased awareness of the clinical/radiological features of SIH is needed to reduce misdiagnosis and/or unrecognition 2. Cranial MR findings of DME with or without subdural collections is almost constant but not unique. Messori et and colleagues recently described the downward brain displacement on mid-sagittal brain MR view as an additional major sign of SIH [1]. Cranial DME without subdural fluid collections has low specificity as illustrated by the patient whose case history was reported by A. Guermazi. 3. Spinal MR features of SIH seem to be less constant and more variable, as described by Rabin et al. [2] and Yousry et al. [3]. Reviews collecting the reported cases and short series may be helpful in clarifying spinal MR “criteria” – if possible – for the condition. A. Salvolini informs us that none of the four patients examined at the spinal level in his published series had abnormalities on the MR images 4. Cranial and spinal MR features of SIH are time dependent which further worsens their low specificity, although they may be constant. The patient reported by A. Guermazi was initially thought to suffer from neoplastic meningeal in-

volvement, which seemed to be a “straight-ahead” diagnostic hypothesis in the context, despite clearly orthostatic headaches. By disclosing shortly later the appearance of more suggestive subdural fluid collection the MRI control led to the re-assessment of the initial diagnosis. The history is very informative and carries useful information for our day-to-day practice Together with the three authors, we strongly feel that SIH has to be hypothesized each time clinical suspicion seems heavy, even in the presence of only scarce MR signs. Awareness of the time dependence and of the possibility of fast reversal of the MR findings is mandatory for the purpose. A. Salvolini clearly summarizes the insights into the pathophysiological mechanisms of the syndrome allowed by MRI, which are still debated in the current literature [3, 4]. At last, we are appropriately reminded that the clinical experience has proved SIH to be a benign condition responding well to uninvasive treatments.

References 1. Messori A, Simonetti BF, Regnicolo L, Bella P di, Logullo F, Salvolini U (2001) Spontaneous intracranial hypotension: the value of brain measurements in diagnosis by MRI. Neuroradiology 43:453–461 2. Rabin BM, Roychowdury S, Meyer JR, Cohen BA, LaPat KD, Russell EJ (1998) Spontaneous intracranial hypotension: spinal MRI findings. Am J Neuroradiol 19:1034–1036 3. Yousry I, Forderreuther S, Moriggl B, Holtmanspotter M, Naidich TP, Straube A, Yousry TA (2001) Cervical MR imaging in postural headache: MR signs and pathophysiological implications. Am J Neuroradiol 22:1239–1250 4. Mokri B (2001) The Monro-Kellie hypothesis: applications in CSF volume depletion. Neurology 56:1746–1748