The Outcome of Surgical Intervention (Ventriculoperitoneal Shunt and Endoscopic Third Ventriculostomy) in Patients With Hydrocephalus Secondary to Tuberculous Meningitis: A Systematic Review

The objective of this study is to analyze the outcome of the safety and efficiency of the surgical interventions (ventriculoperitoneal shunt [VPS] and endoscopic third ventriculostomy [ETV]) in patients with hydrocephalus due to tuberculous (TB) meningitis. A systematic literature search has been conducted using PubMed, Google Scholar, PMC, and ScienceDirect databases from 2001 to 2022 April. A total of 16 studies have been included, irrespective of their design. These studies include patients diagnosed with hydrocephalus secondary to TB meningitis (TBM) treated with VPS or ETV. A systematic review was conducted to determine the efficiency of surgical procedures based on the outcomes and complications associated with these procedures. A total of 2207 patients (aged one month to 68 years) have been included in this study, out of which 1723 underwent VPS and 484 underwent ETV. The overall success rate in the VPS group varied from 21.1% to 77.5%. The overall success rate in the ETV group ranged from 41.1% to 77%. The overall complications rate in the VPS group varied from 10% to 43.8%, and the complications rate in the ETV group varied from 3.8% to 22.5%. After ruling out the significant differences in the average percentages of outcomes and complications followed by VPS and ETV, ETV is suggested in patients with chronic phases of illness because the chances of ETV failure are high during the initial stage. The uncertainty of the ETV gradually decreases over time. To attain favourable long-term outcomes with ETV in patients with TBM hydrocephalus (TBMH), ETV should be performed after chemotherapy, anti-tubercular treatment, and steroids. In addition, ETV is considered beneficial over VP shunt as associated long-term complications are significantly less compared to VP shunt. In contrast, VP shunt is suggested as a modified Vellore grading which shows a more favourable outcome in patients with acute illness than ETV.


Introduction And Background
Tuberculous meningitis (TBM) is a bacterial infection of the central nervous system involving the meninges of the brain and spinal cord. Mycobacterium tuberculosis is the causative organism of TBM. Hydrocephalus is the most common complication of TB meningitis, affecting children more than adults [1]. It is almost always present in patients who have had the disease for four to six weeks and occurs at an early stage of the disease process [1]. The hydrocephalus in patients with tuberculous meningitis could be either the communicating type or the obstructing type, the former being the more common [2]. The developmental issue of the obstructive type of hydrocephalus in tuberculous meningitis is either due to blockage of the fourth ventricle by thick exudates or leptomeningeal scarring [3]. The early stage of this communicating type of hydrocephalus causes thick gelatinous exudates to block the subarachnoid spaces in the base of the brain (more significant in the interpeduncular and ambient cistern). The later stage of the communicating type of hydrocephalus causes the exudates, which leads to dense scarring of the subarachnoid spaces. Communicating hydrocephalus may also result from an overproduction of CSF or secondary to reduced absorption of CSF. Communicating hydrocephalus is seen more recurrently in patients with TBM [3]. According to body weight, the medical management of TBM hydrocephalus (TBMH; communicating type) includes ATT (standard four-drug antitubercular therapy consisting of rifampicin, ethambutol, isoniazid, and pyrazinamide), along with steroids (dexamethasone given if CT showed thick basal exudates and there was evidence of infarcts) [2], and dehydrating agents acetazolamide, furosemide, and mannitol [1]. The surgical management of TBMH includes endoscopic third ventriculostomy (ETV) and ventricular shunting 1 2 1 1 1 (VA, VP, VPL, LP), most commonly ventriculoperitoneal (VP) shunting, which has been the procedure of choice so far [4]. Attempts to relieve pressure symptoms in infants with enlarged heads and adults with papilloedema and high lumbar cerebrospinal fluid (CSF) include cerebellar decompression, lateral and third ventriculostomy, and short-circuits between the ventricular system and subarachnoid space of the cerebral hemispheres [5]. However, the best plan to relieve the communicating hydrocephalus is to persist with intrathecal and systemic streptomycin [5]. High cerebrospinal fluid protein levels delay shunting.
Nevertheless, ventriculoperitoneal shunt (VPS) surgery complications in patients with TBMH are high, with frequent shunt obstructions and shunt infections requiring repeated revisions [4]. Therefore, the clinical grading system determines the patient's treatment strategy [3]. The most commonly used system is the Vellore grading of TBMH (Table 1), proposed by Palur et al. [6]. Alongside, Table 2 briefly discusses modified Vellore grading of patients with TBMH.

Review Methodology
The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines 2020 were followed in this systematic review [8], and the population, intervention, comparison, and outcome (PICO) format was included in this study pattern.
The eligibility criteria of the studies in our survey can be found in Table 3.

Information sources, search strategy and data extraction process
A systematic literature search has been conducted using PubMed, Google Scholar, PMC, and ScienceDirect databases using the relevant keywords and MeSH strategy mentioned below ( Table 4). A total of 16 studies have been included irrespective of their design and having been diagnosed with tuberculous meningitis and treated with VPS surgery or endoscopic third ventriculostomy (ETV). Two researchers worked independently to identify and extract the data. Quality assessment of each study is conducted using appropriate quality appraisal tools (NOS -Newcastle Ottawa Assessment Scale for Prospective and Retrospective Cohort Studies and Critical appraisal guide for Systematic Reviews (randomised studies) from April 21 to 30, 2022. After removing all the duplicates manually and via Endnote, the author's inclusion and exclusion criteria were used to evaluate the study. All the irrelevant studies have been omitted. The third author resolved the differences of opinion between the first two authors. After a complete analysis, 16 articles have finally been considered in this review.
The purpose of the study is to contemplate the outcome, safety, efficiency of surgeries (VPS and ETV), and complications of patients who underwent either ventriculoperitoneal shunt or endoscopic third ventriculostomy. The efficiency of procedures is based on the resolution of signs and symptoms and also on Vellore grading of patients with TBMH.
The search strategy of different databases using relevant keywords and MeSH strategy is summarised in Table 4.

Quality Assessment
Quality assessments of the reviews have been performed based on the guidelines mentioned below. In addition, articles that met at least 70% of the criteria have been included.
We followed the guidelines of the Newcastle Ottawa Assessment Scale for prospective and retrospective cohort studies: (1) Was the exposure and outcome of interest clearly explained? (2) Exposed people? (3) Nonexposed people? (4) The outcome of interest not present at the start of the study (5) Were the people similar? (6) Were the exposure and outcomes measured the same way? (7) Was the follow-up done correctly? (8) Was the follow-up long enough and sufficient enough? (9) Was this study published in an indexed journal? Outcome-based on: YES or NO.
The critical appraisals for systematic review are as follows: (1) Aim of the research; (2) Keyword explanation; (3) MeSH strategy; (4) Did the authors describe all the databases they used to collect the data? (5) Inclusion and exclusion criteria; (6) Did the authors check the quality (critical appraisal) of each study they included in the article? How did they critically appraise it? (7) Is the article published in a reliable database? (8) Were multiple authors involved in data extraction and quality appraisal? (9) Cochrane risk of bias assessment tool. Outcome-based on: YES, PARTIAL YES, NO.

Risk of Bias
The risk of bias in the considered studies has been briefed in Table 5.   Studies of patients with TBMH who underwent either VPS or ETV can be found in Table 6.

S.no Study
Year of

Outcomes
Results for the patients with TBMH who underwent ETV based on the outcomes of success rate and complications can be found in Table 7.

Interpretation
The average follow-up period in the various studies mentioned above varied from one month to five years. The average outcome success rate of the ETV procedure in the studies mentioned above is 61.8%. However, the complication rate of the ETV procedure varied from 3.84% in the study of Aranha et al. to 16.75% in the study of Goyal et al. [3,4,10,13,17,20]. The complication rate of ETV commonly includes CSF leak, perioperative bleed, blocked stoma, the bulge at the ETV site, and meningitis.
Results for the patients with TBMH who underwent VPS based on the outcomes of success rate and complications can be found in Table 8.

Number of patients (n)
Age of the patients

Interpretation
The average follow-up period in the various studies mentioned above varied from two weeks to six years. The average outcome success rate of the VPS procedure in the studies mentioned above is 57.82%. GOS (Glasgow Outcome Scale) and Vellore grading were outcome measures used by a few studies, and some studies used either death or disabilities to determine the outcome. The overall complication rate of the VPS procedure varied from 10% in the study by Kankane et al. to 43.8% in Sil and Chatterjee et al. [3,4,9,14,[18][19][20][21][22]. The common complications in VPS patients include shunt infections, shunt obstructions, intraventricular haemorrhage, and multiple shunt revisions.
The preoperative and postoperative CT brain scans of a patient with TBMH who underwent VPS can be found in Figures 2-4.

Discussion
Hydrocephalus is the most frequent complication of TBM and is profoundly more common in children than in adults. Our study comprised 2207 patients with TBMH who underwent either VPS or ETV. Although various studies determined the efficiency of the surgical intervention based on the clinical outcomes and complications, the indications and timing of VPS and ETV were not steady across the studies. In our study pattern, success rates of ETV in patients with TBMH varied widely from 41.1% to 77% [3,4,[10][11][12][13]16,17,20]. The complication rate in ETV varied from 3.8% in the study of Aranha et al. [4] to 22.55% in Yadav et al. [3,4,10,13,17,20]. The common complications in patients who have undergone ETV include CSF leak, perioperative bleed, blocked stoma, bulge at the ETV site, and meningitis. The presence of advanced clinicalgrade, extra CNS TB, dense adhesions in the prepontine cistern, and unidentifiable third ventricle floor anatomy leads to the failure of ETV [12]. Complex hydrocephalus and associated cerebral infarcts are significant causes of failure to improve after ETV [17]. Results of ETV were better in patients without cistern exudates, good nutritional status, and a thin and identifiable floor of the third ventricle. ETV should be better avoided for acute hydrocephalus in patients with tuberculous meningitis and should be reserved for those who have been on ATT for at least four weeks or those in the phase of chronic burnout and hydrocephalus has developed late [1]. Some authors suggested ETV as worth trying before subjecting the patients to VP shunt as it showed good results in both communicating and obstructing hydrocephalus [4,11]. Few studies regarded ETV as the first choice of management in patients with TBMH despite high CSF cell counts, protein levels, and indistinct third ventricular floor anatomy [4]. On the other hand, a few studies suggested ETV as the first management choice and considered VP shunt and EVD in patients with failed ETV based on the clinical-grade [10]. Thus, there has been a lack of uniformity in the indications for performing endoscopic third ventriculostomy (ETV). On the other hand, success rates of VPS in patients with TBMH have varied widely from 21.1% to 77.5% [3,4,9,14,15,[18][19][20][21][22]. The complication rate in VPS varied from 10% in the study of Kankane et al. [21] to 43.8% in Sil and Chatterjee [3,4,9,14,[18][19][20][21][22]. The common complications in VPS patients include shunt infections, shunt obstructions, intraventricular haemorrhage, multiple shunt revisions, abdominal CSF collections like pseudocyst, subdural hematomas, skin erosions, pneumonia, and meningitis. One of the studies reported that shunt-related complications occurred in four patients and consisted of an obstruction at the lower end of the shunt in three cases, leading to revision. One patient had an infection at the shunt chamber site, leading to skin excoriation and meningitis [20]. A few studies reported that 15.8% of patients expired in the second and fourth postoperative weeks, respectively; among those who had undergone VPS placement, 21.1% of patients had a full recovery without sequelae, and the other 63.2% of patients survived with various sequelae, including paralysis, impaired vision and hearing, mental retardation, and epilepsy [18]. Rizvi et al. suggested that VPS outcome depends upon the clinical severity of TBMH and holds an unpleasant prognosis in HIV-infected patients compared to HIV-uninfected patients [22]. Srikantha et al. suggested a VP shunt as the first choice of management for grade 4 patients with hydrocephalus and recommended it for patients who do not improve with an EVD [15]. A few studies have suggested early VP shunt in patients with non-communicating hydrocephalus [9]. Prognostic factors to rule out the outcome of shunt surgery include the age of the patient, duration of altered sensorium, CSF cell count, and CSF protein levels. However, ETV has the theoretical ascendancy over VPS in enabling the CSF to circulate through the previously inaccessible areas of the brain, which can generally absorb cerebrospinal fluid. ETV also avoids lodging a foreign body in the form of a shunt, hence avoiding complexities like shunt infection, blockage, and abdominal pseudocyst formation [1].

Limitations
The study scale of the ETV group is small compared to the VPS group, and the data extracted from an adult population are inadequate to define any conclusion. In addition, there is a significant shortage of information regarding the follow-up longevity, which might help determine the long-term outcomes and complications of the VPS and ETV procedures and the timing of procedures in patients with TBMH. Finally, apart from the former concerns, there is limited access to the data, and the methods of the studies could be more specific in a better way.

Conclusions
After much interpretation, it is suggested that clinical grading of the patients is a basic and effective method to determine the management of TBMH. Moreover, after ruling out the significant differences in the average percentages of outcomes and complications followed by VPS and ETV, ETV is suggested in patients with chronic illness because the chances of ETV failure are high during the initial phase. However, the uncertainty of the ETV gradually descends over some time. Therefore, to attain favourable long-term outcomes with ETV in patients with TBM, ETV should be performed after chemotherapy, ATT, and steroids. In addition, ETV can be beneficial over VP shunt because it requires fewer incisions, associated long-term complications are significantly less than VP shunt, and there are no implanted foreign bodies. In contrast, VP shunt is suggested in the acute phase of illness as patients in modified Vellore grading show favourable outcomes compared to ETV.

Conflicts of interest:
In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.