J Neurosurg 121:1380–1387, 2014 ©AANS, 2014 Spinal cerebrospinal fluid leak as the cause of chronic subdural hematomas in nongeriatric patients Clinical article JÜRGEN BECK, M.D.,1 JAN GRALLA, M.D., M.SC.,2 CHRISTIAN FUNG, M.D.,1 CHRISTIAN T. ULRICH, M.D.,1 PHILIppE SCHUCHT, M.D.,1 JENS FICHTNER, M.D.,1 LUKAS ANDEREGGEN, M.D.,1 MARTIN GOSAU, M.D.,4 ELKE HATTINGEN, M.D.,5 KLEMENS GUTBROD, M.D.,3 WERNER J. Z’GRAGGEN, M.D.,1,3 MICHAEL REINERT, M.D.,1,6 JÜRG HÜSLER, PH.D.,7 CHRISTOPH OzdOBA, M.D.,2 AND ANDREAS RAABE, M.D.1 Departments of 1Neurosurgery, 2Neuroradiology, and 3Neurology, Bern University Hospital, Bern, Switzerland; 4Department of Cranio-Maxillo-Facial Surgery, University Medical Center, Regensburg, Germany; 5Institute of Neuroradiology, University of Frankfurt, Frankfurt/Main, Germany; 6Department of Neurosurgery, Ospedale Cantonale di Lugano, Switzerland; and 7Institute of Mathematical Statistics and Actuarial Science, University of Bern, Switzerland Object. The etiology of chronic subdural hematoma (CSDH) in nongeriatric patients (≤ 60 years old) often re- mains unclear. The primary objective of this study was to identify spinal CSF leaks in young patients, after formulat- ing the hypothesis that spinal CSF leaks are causally related to CSDH. Methods. All consecutive patients 60 years of age or younger who underwent operations for CSDH between September 2009 and April 2011 at Bern University Hospital were included in this prospective cohort study. The pa- tient workup included an extended search for a spinal CSF leak using a systematic algorithm: MRI of the spinal axis with or without intrathecal contrast application, myelography/fluoroscopy, and postmyelography CT. Spinal patholo- gies were classified according to direct proof of CSF outflow from the intrathecal to the extrathecal space, presence of extrathecal fluid accumulation, presence of spinal meningeal cysts, or no pathological findings. The primary outcome was proof of a CSF leak. Results. Twenty-seven patients, with a mean age of 49.6 ± 9.2 years, underwent operations for CSDH. Hema- tomas were unilateral in 20 patients and bilateral in 7 patients. In 7 (25.9%) of 27 patients, spinal CSF leakage was proven, in 9 patients (33.3%) spinal meningeal cysts in the cervicothoracic region were found, and 3 patients (11.1%) had spinal cysts in the sacral region. The remaining 8 patients (29.6%) showed no pathological findings. Conclusions. The direct proof of spinal CSF leakage in 25.9% of patients suggests that spinal CSF leaks may be a frequent cause of nongeriatric CSDH. (http://thejns.org/doi/abs/10.3171/2014.6.JNS14550) KEY WORDS • chronic subdural hematoma • spinal CSF leak • geriatric • vascular disorders • meningeal cyst HRONIC subdural hematomas (CSDHs) are gener- largement of the subdural hematoma is believed to be due ally regarded to be consequences of head trauma. to microbleedings from fragile walls of sprouting vessels, The most commonly accepted pathophysiological accumulation of fluid in this newly created space follow- explanationC of CSDH is that mild head trauma leads to ing an osmotic gradient created by blood degradation tearing of bridging veins with subsequent bleeding be- products, or a combination of these events.5,10 In older pa- tween the inner layer of the dura mater and the arachnoid, tients, mechanical forces related to brain atrophy enable or between the outer and inner layers of the dura, thus formation and growth of CSDH. A history of mild head creating the hematoma.5,14,28,29 Further and chronic en- trauma in many older patients is suggestive of trauma as a causative agent. In younger patients, brain atrophy is Abbreviations used in this paper: CSDH = chronic subdural generally not so prominent and a history of head trauma hematoma; mRS = modified Rankin Scale; SIH = spontaneous intra- is often not present. cranial hypotension; SPACE = sampling perfection with application Triggered by our experience with a young man with of optimized contrasts using different flip angle evolutions. recurrent CSDH whose recurrence only stopped after 1380 J Neurosurg / Volume 121 / December 2014 Unauthenticated | Downloaded 10/05/21 08:02 AM UTC Spinal CSF leakage and chronic subdural hematoma a spinal CSF leak was sealed, we started to include the Stepwise Protocol of the Search search for spinal CSF leakage into a prospective proto- After a review of existing imaging results or sug- col for all consecutive nongeriatric CSDH patients. Our gestions of CSF leaks, 3-T SPACE imaging of the com- primary objectives were to identify spinal CSF leaks and plete spinal axis was conducted. Next, 0.5 ml of contrast spinal meningeal cysts in our cohort with the hypothesis medium (Magnevist) was injected intrathecally, and T1- that spinal CSF leaks are causally related to CSDH. In this paper we report our findings on the frequency of this weighted MRI of the spinal axis was completed. Myelog- condition. raphy was then performed, and finally, postmyelography CT was completed. If a CSF leak was identified, the im- aging algorithm was stopped with the least invasive study. Methods Example images from a patient are provided in Fig. 3; Study Design following the diagnosis of a CSDH (Fig. 3A), spinal im- aging without contrast demonstrated extrathecal fluid ac- This prospective cohort study was approved by the cumulation (Fig. 3B). The CSF fistula was then proven by local ethics committee of Bern University Hospital. All fluoroscopy (Fig. 3C) and postmyelography CT (Fig. 3D). consecutive patients ≤ 60 years old with CSDH verified by CT or MRI who underwent operations between Sep- Classification of Spinal Imaging Findings tember 1, 2009, and April 12, 2011, were eligible for the study. After formulation of our hypothesis that spinal We classified the findings of the spinal imaging ac- CSF egress may be a cause of CSDH in younger patients, cording to the likelihood of pathological CSF outflow we distributed the study protocol among all staff of the from the intrathecal to the extrathecal space on a scale Departments of Neurosurgery and Neuroradiology at sev- from 0 to 5 in an ascending manner (Table 1): no path- eral meetings and conferences that took place beginning ological findings (category 0), detection of spinal men- 4 months prior to study initiation. Beginning September ingeal cysts in the sacral region (category 1), detection 1, 2009, all staff from both departments began to screen of spinal meningeal cysts in the cervicothoracic region for patients who underwent operations for CSDH. Fur- (category 2), detection of extrathecal fluid accumulation thermore, we used the daily interdisciplinary neurosurgi- on spinal MRI without intrathecal contrast application cal-neuroradiological conferences, where all elective and (category 3), detection of extrathecal contrast (Magnev- emergency cases were presented, as a second screening ist/iopamidol 300 [Iopamiro, Bracco]) on spinal MRI or platform. Patients operated on for a CSDH who were 60 postmyelography CT after intrathecal administration of years of age or younger were eligible for spinal imaging contrast (category 4), and direct visualization of outflow workup. We excluded patients who died early (< 48 hours) of intrathecally administered contrast (iodine) from the due to epilepsy, who presented with recurrent SDH, who intrathecal to the extrathecal space under fluoroscopy were not compliant during spinal imaging, who had recent (category 5). The proof of an existing CSF leak (catego- brain surgery (< 6 months), or who had a shunt system for ries 4 and 5) was defined as the primary outcome. CSF diversion. As a next step, the computerized and writ- ten log books of all operating theaters were screened for Surgery for CSDH patients with CSDH who had not been included in the Whenever possible, the patients were operated on un- study. A flow diagram of the number of patients at each der local anesthesia via the 2-bur-hole technique;18 drain stage of the study is provided in Fig. 1. An idealized dia- insertion was performed if it was considered safe, after gram for how imaging modalities can be used, in order of careful rinsing with large amounts of normal saline so- increasing invasiveness, is shown in Fig. 2. lution.26 For nonliquified space-occupying blood clots, Spinal Imaging open craniotomy under general anesthesia was the first procedure or a backup procedure. For MRI, a Magnetom Avanto 1.5-T or Magnetom Verio 3-T (Siemens) machine was used. The following Postsurgical Care sequences were employed: T1-weighted, T2-weighted, All patients were admitted to the intermediate care magnetization-prepared rapid acquisition gradient echo (MPRAGE), and sampling perfection with application of unit or the intensive care unit after surgery. The drains optimized contrasts using different flip angle evolutions were left in place, restricted to 10 ml/hr and 120 ml/day, (SPACE) with multiplanar reconstructions. In cases of for a maximum of 48 hours. Mobilization of patients was intrathecal contrast application, gadopentetate dimeglu- started on the day of surgery. mine (Magnevist, Bayer) at a standard dose of 0.5 ml Treatment of Spinal CSF Leak dissolved in 9.5 ml CSF was administered via a lumbar puncture at the L3–5 level. In cases in which a spinal CSF leak was detected, the Myelography was performed using a Siemens Artis following treatment algorithm was used: 1) bed rest for Zee Monoplan System (Siemens). A maximum dosage of as long as 3 days; 2) undirected blood patch at the L3–4 30 ml of iodine contrast material was administered after level (with an option to repeat the treatment if necessary); lumbar puncture using an atraumatic puncture kit. Post- 3) directed blood patch under fluoroscopy or CT guid- myelography CT was performed on a LightSpeed Ultra ance (with an option to repeat the treatment if necessary); scanner (GE) immediately after myelography and again 4 and 4) microsurgical exposure and closure of the CSF hours later in selected cases.