Primary hypertension and neurovascular compression: a meta-analysis of magnetic resonance imaging studies

Lateral medullary vascular compression manifesting as paroxysmal hypertension

Neurovascular compression of the rostral ventrolateral medulla (RVLM) has been described as a possible cause of refractory essential hypertension. We present the case of a patient affected by episodes of severe paroxysmal hypertension, some episodes associated with vago-glossopharyngeal neuralgia. Classical secondary forms of hypertension were excluded. Imaging revealed a neurovascular conflict between the posterior inferior cerebellar artery (PICA) and the ventrolateral medulla at the level of the root entry zone of the ninth and tenth cranial nerves (CN IX-X REZ). A MVD of a conflict between the PICA and the RVLM and adjacent CN IX-X REZ was performed, resulting in reduction of the frequency and severity of the episodes. Brain MRI should be performed in cases of paroxysmal hypertension. MVD can be considered in selected patients.

Microvascular decompression can effectively reduce arterial blood pressure in patients with Trigeminal Neuralgia

BACKGROUND

Microvascular decompression (MVD) has been used in the treatment of Trigeminal Neuralgia (TN) and arterial hypertension (HTN). Results of several reports have supported its clinical effectiveness, however, little attention has been paid on arterial blood pressure changes caused by MVD in patients with TN.

METHODS

In this single-center retrospective study, a cohort of 80 patients with TN who underwent MVD between 2021 and 2022 had been reviewed. Clinical data such as age, gender, pain duration, operation time, side and range of pain, HTN history, treatment history, VAS score, mean arterial pressure (MAP), and nausea or vomiting after operation were collected and analyzed via Linear regression to select possible related factors. Then, multiple linear regression of the possible predictors was used to identify the variables that significantly predicted MAP reduction.

RESULTS

The VAS scores of TN patients after MVD surgery was significantly lower than that before operation, irrespective of the gender, side and range of pain, HTN history, RF history, and PONV (Wilcoxon test, P < 0.001). MVD can significantly decreased the blood pressure of TN patients, without interference from other factors. (MAP reduction ratio=14.46% ± 12.32%) (paired t-test, P < 0.001). The univariate and Multiple linear regression analysis showed that the preoperative MAP was significantly related to MAP reduction ratio (P < 0.001).

CONCLUSIONS

In patients with TN, MVD can significantly decrease arterial blood pressure. Blood pressure reductions were more prominent when cases with higher preoperative MAP.

Effect of Microvascular Decompression of the Vagus Root Entry/Exit Zone on Blood Pressure in Patients with Hemifacial Spasm Associated with Essential Hypertension: A Retrospective Clinical Analysis

Background  This study aimed to evaluate blood pressure alterations after microvascular decompression (MVD) surgery in patients with hemifacial spasm (HFS) with coexisting hypertension (HTN). Methods  A total of 56 patients with HFS with concurrent HTN who underwent MVD surgery in our center between 2015 and 2019 were retrospectively analyzed. Patients were divided into control and experimental groups: patients who received MVD treatment for only the facial nerve and those who received MVD for the affected facial nerve, ipsilateral vagus nerve, and adjacent ventrolateral medulla, respectively. Preoperative (3 days) and postoperative (7 days and 6 months) blood pressure measurements were analyzed. Results  No statistically significant differences were observed in gender, age, HFS course, HTN course, HTN grade, and preoperative blood pressure between the two groups. No significant difference was observed between pre- and postoperative blood pressure in the control group. In the experimental group, systolic blood pressure significantly differed between 3 preoperative days and 7 postoperative days ( p  < 0.05), as did diastolic blood pressure ( p  < 0.05). Measurement at 6 postoperative months also showed significant differences for both systolic blood pressure and diastolic blood pressure compared with that at 3 preoperative days ( p  < 0.05). HTN grade according to the World Health Organization classification criteria significantly differed between preoperative and postoperative measurements ( p  < 0.05). Conclusion  Vascular decompression of the ipsilateral vagus nerve roots may improve blood pressure management in patients with HFS with coexisting HTN who undergo MVD. Laterality of involvement (left vs. right) did not significantly differ.

Neurovascular Compression in Arterial Hypertension: Correlation of Clinical Data to 3D-Visualizations of MRI-Findings

Aims:

In this study, we attempted to identify clinical parameters predicting the absence or presence of Neurovascular Compression (NVC) at the Ventrolateral Medulla (VLM) in arterial hypertension (HTN) in MRI findings.

Background:

Cardiovascular and pulmonary afferences are transmitted through the left vagus and glossopharyngeal nerve to the brain stem and vasoactive centers. Evidence supports the association between HTN and NVC at the left VLM. Several independent studies indicate a reduction of HTN after Microvascular Decompression (MVD) of the left. Several independent studies indicate a reduction of HTN after Microvascular Decompression (MVD) of the left VLM. Image processing of MRI provides comprehensible detection of NVC. HTN affects hemodynamic parameters and organs.

Objective:

This study analyzes and correlates clinical data and MRI findings in patients with and without NVC at the VLM in treatment resistant HTN to obtain possible selection criteria for neurogenic hypertension.

Methods:

In 44 patients with treatment resistant HTN, we compared MRI findings of neurovascular imaging to demographic, clinical and lifestyle data, office and 24-hour ambulatory Blood Pressure (BP), and cardiovascular imaging and parameters.

Results:

Twenty-nine (66%) patients had evidence of NVC at the VLM in MRI. Sixteen patients (36%) had unilateral NVC on the left side, 7 (16%) unilateral right and 6 (14%) bilateral NVC. Fifteen (34%) had no evidence of NVC at the VLM. Patients with left sided NVC were significantly younger, than those without NVC (p=0.034). They showed a statistically significant variance in daytime (p=0.020) and nighttime diastolic BP (p<0.001) as the mean arterial pressure (p=0.020). Other measured parameters did not show significant differences between the two groups.

Conclusion:

We suggest to examine young adults with treatment resistant HTN for the presence of NVC at VLM, before signs of permanent organ damage appear. Clinical and hemodynamic parameters did not emerge as selection criteria to predict NVC. MVD as a surgical treatment of NVC in HTN is not routine yet as a surgical treatment of NVC in HTN is not routine yet. Detection of NVC by imaging and image processing remains the only criteria to suggest MVD, which should be indicated on an individual decision.

Is MVD the effective treatment for poorly controlled hypertension?

BACKGROUND

Studies have shown that microvascular decompression (MVD) surgery could improve the clinical symptoms of hemifacial spasm (HFS) and decrease the blood pressure (BP) in patients with refractory hypertension. More positive long-term results are required to establish MVD as a treatment option for high blood pressure (HBP) and to refine the patient selection criteria.

METHODS

From October 2015 to September 2018, based on patient selection for cases with both HFS and poorly controlled HBP of nervous origin, MVD surgeries were performed on 12 patients aiming for better BP control. The patients were followed-up for at least 2 years. The surgical outcomes and associated factors were analyzed.

RESULTS

With respect to neurovascular compression (NVC) of facial nerve, the intra-operative findings concurred with pre-operative radiological findings except that in one case. Intra-operatively ipsilateral cranial nerve (CN) IX-X root exit zone (REZ) and rostral ventrolateral medulla (RVLM) NVCs were confirmed and concordant with pre-operative radiological findings in all 12 cases. 9 Of the 12 cases were completely free of facial spasm after surgery. 2 patients achieved partial relief. 1 patient still suffered from frequent facial spasm. 10 out of 12 patients achieved BP lowering after surgery. The BP of those 10 patients stayed at a relatively stable scale over the follow-up period. Although statistical significance was not obtained, for patients who are operated on the left side and those who have only 1 offensive artery, the surgery might lead to better BP control.

CONCLUSIONS

MVD is a safe and effective treatment for hypertension due to central nervous system (CNS) NVC in patients with both HBP and HFS. Further studies are required to examine long-term outcomes and establish criteria for patient selection.

[Hemifacial spasm]

Hemifacial spasm (HFS), or facial hemispasm, is a paroxysmal hyperkinetic disorder involving muscles innervated by the facial nerve, mainly on the one hand. The development of HFS is based on neurovascular conflict. However, it is impossible to explain the clinical manifestations of HFS only by nerve compression. Both peripheral and central mechanisms are involved in the generation of HFS, with the formation of ephaptic transmission, antidromic excitation, primary or secondary hyper-excitability of the nuclear and supranuclear level of innervation. Two treatment methods are pathogenetically justified: microvascular decompression (MVD) and botulinum toxin (BTX) injections. The effectiveness of MVD is 95.37% with full or partial recovery. The recurrence rate does not exceed 2.4%. Facial nerve paralysis (2.7-22.5%) and hearing loss (1.9-20%) are the most common complications of treatment with the use of the MVD for HFS with partial or complete cure in most cases. Botulinum toxin injection chemo-denervation is a first-line treatment of primary and secondary HFS. HFS is an officially registered indication for the drug dysport (abobotulotoxin) (ABO) in the Russian Federation. Total doses of ABO ranged from 25 to 150 units for one side depending on the severity of the clinical manifestations. Studies demonstrate the statistically significant benefits of HFC treatment with ABO. ABO is generally well-tolerated. Adverse events (up to 3.6%) are transient and include ptosis, lacrimation, blurred vision, double vision, dry eyes and weak facial muscles.

Effects of vascular compression on the rostral ventrolateral medulla for blood pressure variability in stroke patients

BACKGROUNDS

Vascular compression of the rostral ventrolateral medulla (RVLM) has been associated with hypertension or blood pressure (BP) variability. For acute ischemic stroke patients, increased BP variability may cause poor functional outcomes. We tested the hypothesis that RVLM compression was associated with increased BP variability or stroke outcome in acute ischemic stroke patients.

METHODS

Acute ischemic stroke patients (n = 622) with 24-h ambulatory BP monitoring during the subacute phase of stroke (median 9 days from onset) were retrospectively studied. Variability in BP was evaluated with the SD and coefficient of variation of SBP and DBP. The morning surge was also evaluated. The presence of RVLM compression was evaluated using time-of-flight three-dimensional MRI. A poor outcome was defined as a modified Rankin Scale score of 3-6 at 3 months.

RESULTS

Patients with RVLM compression (n = 213) had significantly higher 24-h SBP mean, 24-h SBP SD, 24-h SBP coefficient of variation, 24-h DBP mean, 24-h DBP SD, and 24-h DBP coefficient of variation values and a higher prevalence of morning surge than those without (n = 409). Multiple regression analysis revealed that RVLM compression was associated with increased SBP variability, DBP variability, and morning surge. Despite the significant association between RVLM compression and BP variability, RVLM compression was not associated with poor stroke outcome.

CONCLUSION

Although RVLM compression was closely associated with BP variability in the subacute ischemic stroke phase, an effect of RVLM compression on stroke outcome was not observed.

3D-Visualization of Neurovascular Compression at the Ventrolateral Medulla in Patients with Arterial Hypertension

Purpose

Controversy exists on the association of arterial hypertension (HTN) and neurovascular compression (NVC) at the ventrolateral medulla (VLM). No standardized and reproducible technique has been introduced yet for detection of NVC in HTN. This study aimed to generate, analyze and compare different results of exact reproducible anatomical 3D-representations of the VLM in patients with HTN, based on magnetic resonance imaging (MRI).

Methods

A 3T scanner provided MRI (T2-constructive interference in steady state (CISS) high resolution imaging and three-dimensional Time-of-flight (3D-TOF) angiography) from the posterior fossa of 44 patients with clinical treatment-resistant HTN. Image processing consists of segmentation of the CISS data, registration and fusion of the CISS and TOF data and visualization. For each patient two 3D-visualizations (before and after fusion) were obtained. The reproduction quality of the vessels, flow-related signal variability and pulsation artifacts were analyzed and compared, using a ranking score.

Results

Integrating vascular information from TOF into CISS data reduced artifacts in 3D-visualizations of exclusively processed CISS data. The quality of 3D-visualization of the vessels near the brain stem was significantly improved (p = 0.004). The results were reproducible and reliable. The quality of the 3D-presentations of neurovascular relationships at the VLM improved significantly (p < 0.001).

Conclusion

The 3D-visualization of fused image data provides an excellent overview of the relationship between cranial nerves and vessels at the VLM and simplifies the detection of NVC in HTN. It provides a powerful tool for future clinical and scientific research. Although microvascular decompression (MVD) in treatment resistant HTN is not a standard procedure, it can be discussed in selected patients with intractable severe HTN.

Efficacy of microvascular decompression on the vascular compression type of neurogenic hypertension: A meta-analysis

OBJECTIVE

Neurogenic hypertension is a type of hypertension characterized by increased sympathetic activity. Vascular compression is one of the pathogenic mechanisms of neurogenic hypertension. The sample sizes of currently available studies on MVD in the treatment of hypertension are small, and the results are considerably different. Therefore, we conducted a meta-analysis of the previous literature to obtain the most realistic efficiency and analyzed the current situation of MVD as a treatment option of the vascular compression type of neurogenic hypertension.

METHOD

We systematically searched and identified relevant studies published before July 2019 from PubMed and Embase. Six studies involving 162 participants were included into our final analysis.

RESULT

The data showed that the effective rate of MVD was 70.1% (95% CI: 0.602-0.801). The most common offending vessel was PICA (29.9%), followed by VA/BA (23.9%) and VA/BA plus PICA (12.7%). Complications were mostly related to the VII, VIII, IX, and/or X cranial nerve dysfunction.

CONCLUSION

MVD as a treatment option of the vascular compression type of neurogenic hypertension is effective and safe. In spite of this conclusion, more prospective studies are needed to confirm it. On the other hand, a diagnostic method with higher sensitivity and specificity is necessary.

Microvascular decompression for the treatment of neurogenic hypertension with trigeminal neuralgia

Background

To evaluate the efficacy of microvascular decompression (MVD) in reducing hypertension (HTN) in hypertensive patients with trigeminal neuralgia (TN).

Methods

The clinical data of 58 cases of neurogenic HTN with TN treated in our hospital were retrospectively reviewed. Preoperative MR revealed abnormal blood pressure in the left rostral ventrolateral medulla (RVLM) and the posterior cranial nerve root entry zone (REZ). The patients were divided into control group: only trigeminal nerve was treated with MVD; experimental group: trigeminal nerve, RVLM and REZ were treated with MVD at the same time. The patients were followed up for 6 months to 1 year to observe the changes of blood pressure.

Results

There was no significant difference in gender, age, course of TN, course of HTN, grade of HTN and preoperative blood pressure between the two groups. After operation, the effective rate of HTN improvement with MVD was 32.1% in the control group. There was no significant difference in the preoperative and post operative blood pressure. (P△_SBP = 0.131; P△_BDP = 0.078). In the experimental group, the effective rate was 83.3%. The postoperative blood pressure was significantly lower than preoperative values. (P△_SBP < 0.001; P△_DBP < 0.001).

Conclusions

MVD is an effective treatment for neurogenic HTN. However, the criteria for selecting hypertensive patients who need MVD to control their HTN still needs to be further determined. Possible indications may include: left trigeminal neuralgia, neurogenic HTN; abnormal blood pressure compression in the left RVLM and REZ areas on MR; and blood pressure in these patients can not be effectively controlled by drugs.

Microvascular decompression in patients with hemifacial spasm

PURPOSE

To study blood pressure alterations after microvascular decompression (MVD) surgery in patients with hemifacial spasm (HFS).

METHODS

A retrospective study was performed to review HFS patients who received MVD surgery between January 2014 and December 2016. Vessels that were considered to be responsible for HFS were determined by reviewing the brain magnetic resonance imaging, magnetic resonance angiography, and surgical video. Blood pressure measurements were performed 1 day before (preoperative) and 7 days after (postoperative) the MVD surgery. Pre- and postoperative blood pressure measurements were compared.

RESULTS

A total of 374 patients were included in the study, with 118 (31.6%) male patients, age 53.8 ± 9.9 years old, and 141 (37.7%) patients with hypertension. Systolic blood pressure had statistically significant decrease in patients with (134.5 ± 8.2-132.6 ± 9.1 mmHg, p = .01) or without (125.6 ± 9.1-123.8 ± 10.0 mmHg, p = .01) hypertension. Diastolic blood pressure only had statistically significant decrease in patients with hypertension (83.0 ± 5.8-82.0 ± 6.5 mmHg, p = .04). Analyses in all the study patients and in the subgroup of patients with hypertension showed that more statistically significant blood pressure reductions were observed when left-side vessel or vertebrobasilar artery was involved.

CONCLUSION

In patients with HFS, MVD not only decreased blood pressure in patients with hypertension but also affected blood pressure in patients without hypertension. Blood pressure reductions were more prominent when left-side vessel or vertebrobasilar artery was involved.

A 29-year-old Woman with Recurrent Pregnancy-induced Hypertension Based on Vascular Compression of the Medulla Oblongata

We present a report of a 29-year-old woman with non-dipper type refractory hypertension due to the vascular compression of the medulla oblongata. The patient was diagnosed with hypertension at 17 years of age and underwent emergency Caesarean section at 26 weeks of gestation during 2 pregnancies due to severe high blood pressure. We suspected medullary compression by the curved posterior inferior cerebellar artery as the cause of her intractable hypertension, and she underwent Jannetta's decompression surgery. After the surgery, her blood pressure swiftly decreased to almost within the normal range, and her blood pressure pattern normalized to dipper type.

Treatment of Blepharospasm/Hemifacial Spasm

OPINION STATEMENT

The treatment of both hemifacial spasm (HFS) and blepharospasm (BEB) requires making the appropriate clinical diagnosis. Advance imaging and electrophysiologic studies are useful; however, one's clinical suspicion is paramount. The purpose of this review is to summarize current and emerging therapies for both entities. Botulinum toxin (BTX) remains the first-line therapy to treat both conditions. If chemodenervation has failed, surgery may be considered. Due to the risks associated with surgery, the benefits of this option must be carefully weighed. Better surgical outcomes are possible when procedures are performed at tertiary centers with experienced surgeons and advanced imaging techniques. Microvascular decompression is an efficacious method to treat HFS, and myectomy is an option for medication-refractory BEB; the risks of the latter may outweigh any meaningful clinical benefits. Oral agents only provide short-term relief and can cause several unwanted effects; they are reserved for patients who cannot receive BTX and/or surgery. Transcranial magnetic stimulation has gained some traction in the treatment of BEB and may provide safer non-invasive options for refractory patients in the future.

Vascular tortuosity in relationship with hypertension and posterior fossa volume in hemifacial spasm

Background

Hemifacial spasm (HFS) is a disabling neurological condition. Vascular tortuosity in HFS patients has not been quantified objectively and its relationship with hypertension and posterior fossa volume (PF) is unknown. In a case control magnetic resonance imaging and angiographic (MRI/A) study, we quantified and compared the vascular tortuosity in HFS and controls, and evaluated its relationship with hypertension and PF.

Methods

Using a commercially available vessel probe tool, an index of tortuosity based on vessel over chord length was employed to quantify vascular tortuosity of the vertebral (VA) and basilar arteries (BA) in 79 subjects (40 HFS, 39 controls).

Results

The tortuosity index of the BA (1.09 vs 1.16, p = 0.26, 95 % CI 1.07, 1.23), RVA (1.15 vs 1.15, p = 0.83, 95 % CI 1.06, 1.38) and LVA (1.14 vs 1.288, p = 0.16, 95 % CI 1.14, 1.44) was not different between HFS and controls, with adjustments for PF volume and hypertension.

Conclusions

Contrary to popular belief, our study showed that taking into account hypertension and PF volume, vascular tortuosity of the vertebrobasilar arteries is unlikely to be a major etiologic factor in HFS, though its role in select individuals cannot be excluded. The complex interplay of facial nerve hyperexcitability, genetic predisposition, vascular tortuosity, posterior fossa volume and hypertension needs to be further evaluated.

Revisiting the link between hypertension and hemifacial spasm

The relationship between hypertension and hemifacial spasm (HFS) has been debated. Microvascular decompression surgery is effective in some HFS patients with uncontrolled hypertension. To address current gaps in knowledge, we conducted a meta-analysis of case-control studies that have examined the prevalence of hypertension in HFS patients compared to non-HFS controls. We also evaluated the implications and limitations of the pooled studies. We identified 62 studies from PubMed, The Cochrane Library, Web of Science and Scholar.google.com and six studies that fit our inclusion criteria were included. A random-effects model was used to derive the pooled estimate of the Odds Ratio. The data was plotted on a Forest plot. A pooled analysis involving 51585 subjects, 549 cases, 720 neurological controls and 50316 controls from the general population, showed that HFS patients had a higher chance of developing hypertension (OR = 1.72, 95% CI = (1.12, 2.31), p-value  <0.001). The prevalence of hypertension was higher in HFS patients as compared to non-HFS patients. This meta-analysis highlights a positive correlation between hypertension and HFS. Blood pressure should be closely monitored during the follow-up of HFS patients. Preliminary links between ventrolateral medullary (VLM) compression and HFS should be further evaluated in future studies.

Hypertension of neurogenic origin: effect of microvascular decompression of the CN IX-X root entry/exit zone and ventrolateral medulla on blood pressure in a prospective series of 48 patients with hemifacial spasm associated with essential hypertension

OBJECT

In spite of solid anatomical and physiological arguments and the promising results of Jannetta in the 1970s, treating essential hypertension by microvascular decompression (MVD) of the brainstem has not gained acceptance as a mainstream technique. The main reason has been a lack of established selection criteria. Because of this, the authors' attempts have been limited to patients referred for MVD for hemifacial spasm (HFS) who also had hypertension likely to be related to neurovascular compression (NVC).

METHODS

Of 201 patients referred for HFS, 48 (23.8%) had associated hypertension. All had high-resolution MR images that demonstrated NVC. All underwent MVD of the root exit/entry zone (REZ) of the ninth and tenth cranial nerves (CN IX-X) and adjacent ventrolateral medulla in addition to the CN VII REZ. Effects on hypertension, graded using the WHO classification, were studied up to the latest follow-up, which was 2–16 years from the time of surgery, 7 years on average. Also, effects of MVD on blood pressure (BP) according to the side of vascular compression were evaluated.

RESULTS

Preoperatively, hypertension was severe in all but 1 of the patients; in spite of medical treatment, 47 patients still had WHO Grade 1 or 2 hypertension, and 18 still had unstable BP. After MVD, at latest follow-up, BP had returned to normal (i.e., systolic pressure < 140 mm Hg) in 28 patients; 14 of these patients (29.10% of the whole series) were able to maintain normal BP without any antihypertensive treatment; the other 14 still required some medication to maintain their BP below 140 mm Hg (p < 0.0001). Also, at latest follow-up, BP remained unstable in only 8 of the 18 patients with instability prior to MVD (p < 0.02). Analysis according to side of compression showed that of the 30 patients with left-sided compression, 17 had their BP normalized (without medication in 11 cases), and of the 18 patients with right-sided compression, 11 had their BP normalized (without medication in 3 cases). The difference between sides was not significant.

CONCLUSIONS

These results argue for considering MVD for the treatment of hypertension likely to be due to NVC at the CN IX-X REZ and adjacent ventrolateral medulla. Criteria for selecting patients with hypertension alone still need to be established and could include the following indications: apparently essential hypertension, likely to be neurogenic, in patients in whom high-resolution MRI shows clear-cut images of NVC at the CN IX-X REZ and adjacent ventrolateral medulla and in whom BP cannot be controlled by medical treatment.

Is there a place for microsurgical vascular decompression of the brainstem for apparent essential blood hypertension? a review

There are anatomical and physiological evidences that the ventrolateral (VL) region of the medulla plays an important role in blood pressure regulation and that dysfunction at this level may generate hypertension (HT). Vascular compression by a megadolicho-artery from the vertebrobasilar arterial system at the root entry/exit zone (REZ) of the glossopharyngeal (IXth) and vagal (Xth) cranial nerves (CNs) and the adjacent VL aspect of the medulla has been postulated as a causal factor for HT from neurogenic origin. The first attempts at microvascular decompression (MVD) of the IX-Xth CNs together with the neighbouring VL brainstem was revealed promising. These surgical attempts, as well as the numerous MRI studies, with the goal to detect and identify likely responsible neurovascular conflicts (NVC), are reviewed. Established criteria for indication of MVD as an aetiological treatment of apparent essential HT are still needed.

[Neurovascular compression of the medulla oblongata: a rare cause of secondary hypertension]

Compression of the rostral ventrolateral medulla oblongata is one of the rarely identified causes of refractory hypertension. In patients with severe, intractable hypertension caused by neurovascular compression, neurosurgical decompression should be considered. The authors present the history of a 20-year-old man with severe hypertension. After excluding other possible causes of secondary hypertension, the underlying cause of his high blood pressure was identified by the demonstration of neurovascular compression shown by magnetic resonance angiography and an increased sympathetic activity (sinus tachycardia) during the high blood pressure episodes. Due to frequent episodes of hypertensive crises, surgical decompression was recommended, which was performed with the placement of an isograft between the brainstem and the left vertebral artery. In the first six months after the operation, the patient's blood pressure could be kept in the normal range with significantly reduced doses of antihypertensive medication. Repeat magnetic resonance angiography confirmed the cessation of brainstem compression. After six months, increased blood pressure returned periodically, but to a smaller extent and less frequently. Based on the result of magnetic resonance angiography performed 22 months after surgery, re-operation was considered. According to previous literature data long-term success can only be achieved in one third of patients after surgical decompression. In the majority of patients surgery results in a significant decrease of blood pressure, an increased efficiency of antihypertensive therapy as well as a decrease in the frequency of highly increased blood pressure episodes. Thus, a significant improvement of the patient's quality of life can be achieved. The case of this patient is an example of the latter scenario.

Methodology and reporting of meta-analyses in the neurosurgical literature

OBJECT

Neurosurgeons are inundated with vast amounts of new clinical research on a daily basis, making it difficult and time-consuming to keep up with the latest literature. Meta-analysis is an extension of a systematic review that employs statistical techniques to pool the data from the literature in order to calculate a cumulative effect size. This is done to answer a clearly defined a priori question. Despite their increasing popularity in the neurosurgery literature, meta-analyses have not been scrutinized in terms of reporting and methodology.

METHODS

The authors performed a literature search using PubMed/MEDLINE to locate all meta-analyses that have been published in the JNS Publishing Group journals (Journal of Neurosurgery, Journal of Neurosurgery: Pediatrics, Journal of Neurosurgery: Spine, and Neurosurgical Focus) or Neurosurgery. Accepted checklists for reporting (PRISMA) and methodology (AMSTAR) were applied to each meta-analysis, and the number of items within each checklist that were satisfactorily fulfilled was recorded. The authors sought to answer 4 specific questions: Are meta-analyses improving 1) with time; 2) when the study met their definition of a meta-analysis; 3) when clinicians collaborated with a potential expert in meta-analysis; and 4) when the meta-analysis was the only focus of the paper?

RESULTS

Seventy-two meta-analyses were published in the JNS Publishing Group journals and Neurosurgery between 1990 and 2012. The number of published meta-analyses has increased dramatically in the last several years. The most common topics were vascular, and most were based on observational studies. Only 11 papers were prepared using an established checklist. The average AMSTAR and PRISMA scores (proportion of items satisfactorily fulfilled divided by the total number of eligible items in the respective instrument) were 31% and 55%, respectively. Major deficiencies were identified, including the lack of a comprehensive search strategy, study selection and data extraction, assessment of heterogeneity, publication bias, and study quality. Almost one-third of the papers did not meet our basic definition of a meta-analysis. The quality of reporting and methodology was better 1) when the study met our definition of a meta-analysis; 2) when one or more of the authors had experience or expertise in conducting a meta-analysis; 3) when the meta-analysis was not conducted alongside an evaluation of the authors' own data; and 4) in more recent studies.

CONCLUSIONS

Reporting and methodology of meta-analyses in the neurosurgery literature is excessively variable and overall poor. As these papers are being published with increasing frequency, neurosurgical journals need to adopt a clear definition of a meta-analysis and insist that they be created using checklists for both reporting and methodology. Standardization will ensure high-quality publications.