CSF loss: the search for the leak

Spontaneous intracranial hypotension (SIH) occurs as a result of a loss of cerebral fluid through a leak in the so-called dura mater. It is therefore also referred to as cerebrospinal fluid loss syndrome. SIH is an often-overlooked condition that affects an estimated 5 in 100,000 people each year. It is caused by a small tear in the dura mater in the area of the spine, usually from a sharp-edged micro-spur (calcified disc herniation), or – more rarely – from a tear in a nerve root bag. The continuous loss of cerebrospinal fluid and the resulting negative pressure in the skull typically lead to orthostatic headaches, i.e. pain that increases in intensity when standing.

In a detailed review article in The Lancet Neurology, the international research team summarizes the current state of knowledge. Tomas Dobrocky, senior neuroradiologist at the University Institute of Diagnostic and Interventional Neuroradiology at Inselspital, Bern University Hospital, notes: «Ten years ago, SIH was rarely on a clinician's list of differential diagnoses. Thanks to research efforts in recent years, pathophysiological relationships have been identified and new therapeutic options established. The primary aim of the review article is to raise awareness of CSF loss syndrome in broader specialist circles beyond neurology. We assume that many cases are still being diagnosed too late or not at all.»

An important clinical sign of the presence of a spontaneous CSF leak is the so-called orthostatic headache. The pain increases in intensity when standing and quickly improves after lying down. The next step, the precise localization of the leak, is very challenging, as it may be an opening the size of a pinhead somewhere in the spine. Eike Piechowiak, Hospital Specialist I at the University Institute for Diagnostic and Interventional Neuroradiology at Inselspital, Bern University Hospital, explains the procedure developed at Inselspital, which has since been adopted by centers worldwide: «As part of a step-by-step approach, special MRI images of the head and spine are first taken. In a second step, the exact location of the leak is determined by means of dynamic examinations in the myelography. The therapy involves a blood patch (sealing the leak with autologous blood) or a neurosurgical procedure.»

The team of authors from the centers at Toronto Western Hospital (CAN), Mayo Clinic Rochester (USA), the University of Freiburg (DE) and Inselspital, Bern University Hospital also comment on the questions and tasks that are still open. In particular, the aim is to achieve a reliable earlier diagnosis using means that are as practical as possible. Prof. Dr. med. Andreas Raabe, clinic director and head physician of the University Department of Neurosurgery at Inselspital, Bern University Hospital, says: «The many years of research work will be incorporated into future diagnostic and therapeutic guidelines. Close international cooperation between the centers will support this. Future research questions will explore ways to localize a CSF leak more quickly and without invasive examinations. We will have to study the therapeutic options in detail and address the question of the long-term effects of spontaneous CSF loss.»

Tomas Dobrocky, Patrick Nicholson, Levin Häni, Pasquale Mordasini, Timo Krings, Waleed Brinjikji, Jeremy K Cutsforth-Gregory, Ralph Schär, Christoph Schankin, Jan Gralla, Vitor M Pereira, Andreas Raabe, Richard Farb, Jürgen Beck, Eike I Piechowiak. Spontaneous intracranial hypotension: searching for the CSF leak, The Lancet Neurology. 2022.