Acute hydrocephalus after aneurysmal subarachnoid hemorrhage: The controversial role of lumbar puncture

The origin of acute hydrocephalus after aneurysmal subarachnoid hemorrhage (aSAH), its optimal therapeutic regimen and the relationship with shunt-dependent hydrocephalus (SDHC) remain matter of investigation despite decades of study. Tack and colleagues sought to investigate if lumbar puncture (LP) could treat acute hydrocephalus avoiding external ventricular drainage (EVD) insertion in selected cases of aSAH [ [1] Tack R.W. Lindgren A. Vergouwen M.D.I. van der Zwan A. van der Schaaf I. Rinkel GJE lumbar puncture for treating acute hydrocephalus after aneurysmal subarachnoid haemorrhage. J. Neurol. Sci. 2022; Google Scholar ]. The authors reviewed their prospectively collected database of 1391 aSAH patients who were admitted between 2007 and 2017. Acute hydrocephalus occurred in 473 patients (34%) and 388 (82%) were treated. According to their protocol, LP was considered before inserting an EVD in patients without complete filling with blood of the third or fourth ventricle or space occupying intracerebral or subdural hemorrhages. In addition, in poor grade aSAH patients was preferentially positioned an EVD. LP was the initial treatment in 86 patients with early clinical improvement in 70 patients (81%). Hydrocephalus resolved after one or two LPs in 39 patients (45%) while external lumbar drainage (ELD) was required in 25 patients (29%). In this cohort of 86 patients treated with LP, SDHC occurred in only six patients (7%). According to the results of this study, roughly half of patients treated with LP for symptomatic acute hydrocephalus following aSAH did not require EVD or ELD. The limitations of this retrospective, monocentric, nonrandomized, controlled cohort analysis, including selection bias, have been detailed by the authors. That the simple technique of LP could provide such significant improvement on acute hydrocephalus after aSAH is noteworthy, but these findings are not entirely new [ [2] Hasan D. Lindsay K.W. Vermeulen M treatment of acute hydrocephalus after subarachnoid hemorrhage with serial lumbar puncture. Stroke. 1991; 22: 190-194 Crossref PubMed Scopus (69) Google Scholar ]. Comparable results were described by Hasan and colleagues that reported clinical improvement in twelve (71%) of the 17 patients treated with serial lumbar punctures for acute hydrocephalus after aSAH [ [2] Hasan D. Lindsay K.W. Vermeulen M treatment of acute hydrocephalus after subarachnoid hemorrhage with serial lumbar puncture. Stroke. 1991; 22: 190-194 Crossref PubMed Scopus (69) Google Scholar ]. In their series four of these 17 patients required an internal shunt [ [2] Hasan D. Lindsay K.W. Vermeulen M treatment of acute hydrocephalus after subarachnoid hemorrhage with serial lumbar puncture. Stroke. 1991; 22: 190-194 Crossref PubMed Scopus (69) Google Scholar ]. When a LP is planned in patients with aSAH the potential risk of aneurysm rebleeding should be considered. In fact, a sudden change of the transmural pressure after CSF drainage could contribute to aneurysm rerupture. In a recent meta-analysis, the rate of rebleeding after EVD insertion was 8.7% [ [3] Cagnazzo F. Gambacciani C. Morganti R. Perrini P aneurysm rebleeding after placement of external ventricular drainage: a systematic review and meta-analysis. Acta Neurochir. 2017; 159: 695-704 Crossref PubMed Scopus (21) Google Scholar ]. Similarly, in the series of Hasan and colleagues the rebleeding rate after LP was 12% suggesting that aneurysm occlusion should precede CSF drainage [ [2] Hasan D. Lindsay K.W. Vermeulen M treatment of acute hydrocephalus after subarachnoid hemorrhage with serial lumbar puncture. Stroke. 1991; 22: 190-194 Crossref PubMed Scopus (69) Google Scholar ]. It is unclear why lumbar drainage of CSF through LP would be effective in treating acute hydrocephalus and reducing occurrence of SDHC. The pathophysiological concept underlying the use of LP is that it promotes CSF circulation from the ventricular system toward the spinal subarachnoid space. In a seminal paper, Klimo and colleagues [ [4] Klimo P. Kestle J.R.W. MacDonald J.D. Schmidt RH marked reduction of cerebral vasospasm with lumbar drainage of cerebrospinal fluid after subarachnoid hemorrhage. J. Neurosurg. 2004; 100: 215-224 Crossref PubMed Scopus (207) Google Scholar ] found that CSF drained from the ventricles is generally less hemorrhagic than CSF drained from spinal subarachnoid space, suggesting that EVD may promote stasis within the CSF pathways. Accordingly, lumbar CSF drainage seems to expedite the clearance of subarachnoid and ventricular blood on CT scans when compared with controls treated with EVD resulting in effective resolution of acute hydrocephalus. The effectiveness of lumbar CSF drainage on the development of SDHC after aSAH is controversial. The main mechanism implicated as causative factor for the development of SDHC consists in leptomeningeal fibrosis with resultant increased resistance to CSF ouflow. The low rate (7%) of SDHC in the present study is described in a subgroup of patients not comparable with the data of current literature, which indicate a rate greater than 20% [ [5] di Russo P. Di Carlo D.T. Lutenberg A. Morganti R. Evins A.I. Perrini P shunt-dependent hydrocephalus after subarachnoid hemorrhage. J. Neurosurg. Sci. 2020; 64: 181-189 Crossref PubMed Scopus (16) Google Scholar ]. Some of the main predictors of SDHC including high Hunt and Hess scale score, high Fisher grade and intraventricular blood were considered contraindications to perform LP in the study of Tack and colleagues [ [1] Tack R.W. Lindgren A. Vergouwen M.D.I. van der Zwan A. van der Schaaf I. Rinkel GJE lumbar puncture for treating acute hydrocephalus after aneurysmal subarachnoid haemorrhage. J. Neurol. Sci. 2022; Google Scholar ]. In fact, previous investigations did not find a significant reduction in the occurrence of CSDH with the use of LP or ELD [ [4] Klimo P. Kestle J.R.W. MacDonald J.D. Schmidt RH marked reduction of cerebral vasospasm with lumbar drainage of cerebrospinal fluid after subarachnoid hemorrhage. J. Neurosurg. 2004; 100: 215-224 Crossref PubMed Scopus (207) Google Scholar ]. In summary, the authors provided some insight on the treatment of acute hydrocephalus after aSAH, emphasizing the role of the LP. There are many questions that remain to be answered including the amount of the CSF to be drained with LP, the role of ELD, and the risk of SDHC when LP is used instead of EVD. Only a randomized prospective trial could solve these unanswered questions and hopefully confirm that the LP can avoid ELD or EVD in a selected group of patients with aneurysmal acute hydrocephalus.