Paramedian versus midline approach of spinal anesthesia: a systematic review and meta-analysis with trial sequential analysis.

PURPOSE: Midline approach of spinal anesthesia has been widely used for patients undergoing surgical procedures. However, it might not be effective for obstetric patients and elderly with degenerative spine changes. Primary objective was to examine the success rate at the first attempt between the paramedian and midline spinal anesthesia in adults undergoing surgery. METHODS: Databases of MEDLINE, EMBASE, and CENTRAL were searched from their starting date until February 2023. Randomized clinical trials (RCTs) comparing the paramedian versus midline approach of spinal anesthesia were included. The primary outcome was the success rate at the first attempt of spinal anesthesia. RESULTS: Our review included 36 RCTs (n = 5379). Compared to the midline approach, paramedian approach may increase success rate at the first attempt but the evidence is very uncertain (OR: 0.47, 95% CI 0.27-0.82, ρ = 0.007, level of evidence:very low). Our pooled data indicates that the paramedian approach likely reduced incidence of post-spinal headache (OR: 2.07, 95% CI 1.51-2.84, ρ < 0.00001, level of evidence:moderate). The evidence suggests that the paramedian approach may result in a reduction in the occurrence of paresthesia (OR: 1.61, 95% CI 1.06-2.45, ρ = 0.03, level of evidence:low). CONCLUSIONS: Our meta-analysis of 36 RCTs showed that paramedian approach may result in little to no difference in success rate at the first attempt owing to its very low level of evidence. However, given the low level of evidence and studies with small sample sizes, these findings need to be interpreted with caveat. CLINICAL TRIAL REGISTRATION NUMBER: CRD42023397781.

Factors affecting parental refusal of lumbar puncture in Iraqi children in COVID-19 era: a cross-sectional study.

OBJECTIVE: To assess the frequency and causes of parental lumbar puncture refusal for their children. METHODS: The cross-sectional study was conducted at the Central Child Teaching Hospital, Baghdad, Iraq, from October 1, 2021, to April 1, 2022, and comprised children aged at least >1 month at the emergency department who had been advised to undergo lumbar puncture. Data from the mother of the child was collected using an interviewbased questionnaire, exploring. demographic characteristics, the cause of lumbar puncture refusal, as well as knowledge of the advantages and risks of lumbar puncture. Data was analysed using SPSS 26. RESULTS: There were 128 children with a mean age of 3.9±2.1 years (range: 1-120 months). The parents of 18(14%) patients refused the procedure, and the most frequent reason was fear of paralysis 12(67%). Refusal was significantly associated with mother's age, parents' levels of education, and parents' knowledge of the risks of lumbar puncture (p<0.05). CONCLUSIONS: Raising public awareness and parents' educational level regarding the necessity and safety of lumbar puncture procedure is vital to decrease the refusal rate and ensure a better health outcome.

Feasibility of intrathecal therapeutic injections in spinal muscular atrophy patients via a percutaneous transsacral hiatus route: An initial neuroimaging morphometric study.

INTRODUCTION/AIMS: Standard fluoroscopic lumbar puncture (LP) can be impossible in patients with severe spinal deformities from spinal muscular atrophy (SMA) who require intrathecal nusinersen therapy. There usually exists a straight trajectory in the lower sacral canal (SC) that could allow image-guided percutaneous transsacral hiatus puncture of the lumbosacral dural sac. In this study we determine whether sacra are comparatively straighter in SMA patients (SMAps) vs healthy controls (HCs), which may facilitate unhindered transsacral hiatus spinal needle insertion for intrathecal nusinersen therapy. METHODS: We retrospectively analyzed lumbosacral spine computed tomograms (CTs) or CT-myelogram images of 38 SMAps and age- and sex-matched HCs. We digitally measured ventrodorsal sacral curvatures, SC surface areas, dural sac termination levels, and distances from sacral hiatus to the most caudad aspects of dural sacs ("needle distance"). RESULTS: Mean ages of HCs and SMAps were 32.7 and 31.7 years, respectively, with dural sacs terminating at similar levels. Mean values for morphometrics were: (a) midsagittal SC surface area for HCs = 701.2 mm2 , and for SMAps = 601.5 mm2 (not statistically significant [ns]); (b) using a "line method," sacral curvature for HCs = 61.9°, and SMAp = 35.7° (P = .0009), and was similar when using an "angle summation method"; (c) width of sacral hiatus for HCs = 14.9 mm, and SMAps = 15.0 mm (ns); and (d) "needle distance" for HCs = 54.7 mm, and SMAps = 49.9 mm (ns). DISCUSSION: SMAps have significantly straighter sacra compared with HCs, which theoretically renders them more amenable to percutaneous transsacral hiatus puncture of the dural sac.

Feasibility of percutaneous dural sac puncture via a posterior trans-sacral foraminal conduit approach: a CT morphometric analysis.

We assess the theoretical feasibility of percutaneous posterior sacral foramen (pSF) needle puncture of the sacral dural sac (DS) by studying the three-dimensional imaging anatomy of pSFs relative to the sacral canal (SC). On CT images of 40 healthy subjects, we retrospectively studied sacral alae passageways from SC to pSFs in all three planes to determine if an imaginary spinal needle could theoretically traverse S1 or S2 pSFs in a straight path toward DS. If not straight, we measured multiplane angulations and morphometrics of this route. We found no straight connections between S1 or S2 pSFs and SC. Instead, there were bilateral spatially complex dorsoventral M-shaped "foraminal conduits" (FCs; common, ventral, and dorsal) from SC to anterior SFs and pSFs that would prevent percutaneous straight needle puncture of the DS. This detailed knowledge of the sacral FCs will be useful for accurate imaging interpretation and interventional procedures on the sacrum.

An unexpected effect of traumatic and bloody lumbar puncture among patients with primary headaches in emergency department.

BACKGROUND: This study aimed to investigate the association between traumatic tap and the incidence of post-dural puncture headache (PDPH) following lumbar puncture (LP) among patients who underwent LP with a primary discharge diagnosis of primary headache in the emergency department (ED). METHODS: We retrospectively reviewed the medical records of patients who visited a single tertiary ED with the symptom of a headache and underwent LP for cerebrospinal fluid (CSF) analysis between January 2012 and January 2022. Patients who met the definition of PDPH and revisited the ED or outpatient clinic within 2 weeks of discharge were included. For comparative analysis, we divided the groups according to CSF RBC counts (group 1, CSF RBC <10 cells/µL; group 2, 10-100 cells/µL; group 3, ≥100 cells/µL). The primary outcome was the difference in CSF RBC counts between the ED or outpatient clinic revisiting patients who underwent LP within 2 weeks after discharge from the ED. The secondary outcomes were the admission rate and risk factors for PDPH; sex, age, needle size, and CSF pressure. RESULTS: Data from 112 patients were collected; PDPH was reported in 39 patients (34.8%), and 40 (35.7%) patients were admitted. The median (interquartile range) CSF RBC count was 10 [2-100.8] cells/µL. One-way analysis of variance test of the mean differences among the three groups showed no differences in age, the duration of headache before LP, PLT counts, PT, or aPTT among the groups. There were differences in the number of admitted patients (30 vs. 7 vs. 3, P < 0.001) and the incidence of PDPH (29 vs. 6 vs. 4, P < 0.003). In the comparison of the PDPH and non-PDPH groups, there were differences in age (28.7 ± 8.4 years vs. 36.9 ± 18.4 years, P = 0.01) and the admission rate (85% vs. 9%, P < 0.001). CONCLUSIONS: Notably, our results suggest that traumatic LP may be an unexpected factor in reducing the occurrence rate of PDPH. Consequently, the admission rate for PDPH was significantly reduced among patients with traumatic LP and those with primary headaches. In this study, we collected and analyzed the data from a relatively small sample size of 112 patients. Further studies are needed to evaluate the relationship between traumatic LP and PDPH.

Interpretation of white blood cell counts in the cerebrospinal fluid of neonates with traumatic lumbar puncture: a retrospective cohort study.

BACKGROUND: Difficulty in interpreting white blood cell (WBC) counts in cerebrospinal fluid (CSF) complicates the diagnosis of neonatal meningitis in traumatic lumbar punctures (LP). The aim of our study was to determine the correction factor for WBC counts in traumatic LP that offers the greatest diagnostic efficacy in meningitis. METHODS: We conducted a retrospective observational study of LP in neonates between January 2014 and December 2020. Traumatic LP was defined as a red blood cell (RBC) count ≥ 1,000 cells/mm3 CSF and pleocytosis as WBCs ≥ 20 cells/mm3 CSF. The CSF RBC:WBC ratio was analyzed by linear regression to determine a new correction factor. Cell count adjustments were also studied using the 500:1, the 1,000:1 ratio method, and the peripheral blood RBC:WBC ratio, using ROC curves and studies of accuracy (sensitivity and specificity). RESULTS: Overall, 41.0% of the 1,053 LPs included in the study were traumatic. The best results for effective WBC correction were the method based on the peripheral blood ratio (sensitivity = 1.0 and specificity = 0.9 for bacterial meningitis and sensitivity = 0.8 and specificity = 0.9 for viral meningitis) and the 400:1 ratio (sensitivity = 1.0 and specificity = 0.8 for bacterial meningitis and sensitivity = 0.8 and specificity = 0.8 for viral meningitis) obtained from linear regression (95% CI 381.7-427.4; R2 = 0.7). CONCLUSION: Both the peripheral blood correction and the 400:1 correction reduce the number of neonates classified with pleocytosis who were not eventually diagnosed with meningitis. Both methods might be a useful tool to clarify the neonatal meningitis diagnosis, offering neonatologists the possibility to assess the WBC count in traumatic LP.

Analysis of patients receiving ≥ 100 mSv during a computed tomography intervention.

OBJECTIVE: To identify a patient cohort who received ≥ 100 mSv during a single computed tomography (CT)-guided intervention and analyze clinical information. MATERIALS AND METHODS: Using the dose-tracking platform Radimetrics that collects data from all CT scanners in a single hospital, a patient-level search was performed retrospectively by setting a threshold effective dose (E) of 100 mSv for the period from January 2013 to December 2017. Patients who received ≥ 100 mSv in a single day during a single CT-guided intervention were then identified. Procedure types were identified, and medical records were reviewed up to January 2020 to identify patients who developed short- and/or medium-term (up to 8 years) medical consequences. RESULTS: Of 8952 patients with 100 mSv+, there were 33 patients who underwent 37 CT-guided interventions each resulting in ≥ 100 mSv. Procedures included ablations (15), myelograms (8), drainages (7), biopsies (6), and other (1). The dose for individual procedures was 100.2 to 235.5 mSv with mean and median of 125.7 mSv and 111.8 mSv, respectively. Six patients (18 %) were less than 50 years of age. During the study period of 0.2 to 7 years, there were no deterministic or stochastic consequences identified in this study cohort. CONCLUSIONS: While infrequent, CT-guided interventions may result in a single procedure dose of ≥ 100 mSv. Awareness of the possibility of such high doses and potential for long-term deleterious effects, especially in younger patients, and consideration of alternative imaging guidance and/or further dose optimization should be strongly considered whenever feasible. KEY POINTS: • Although not so frequent, CT-guided interventions may result in a single procedure dose of ≥ 100 mSv • Procedures with potential for high dose includes ablations, myelograms, drainages, and biopsies.

Imaging anatomy of the vertebral canal for trans-sacral hiatus puncture of the lumbar cistern.

A standard lumbar puncture may be impossible for many anatomic or technical reasons. Previous accounts of caudal epidural anesthesia and other procedures via the sacral hiatus prompted us to test if image-guided percutaneous trans-sacral hiatus access to the lumbosacral subarachnoid cistern would be anatomically feasible. To study vertebral canal morphometry and curvature, we analyzed midsagittal computed tomography-myelogram images of 40 normal subjects and digitally measured sacral curvatures between S1 to S5 and S2 to S4 using two methods whereby a lower angle signifies a straighter sacrum. We measured midsagittal vertebral canal area, hiatus width, dural sac termination levels, and distance from sacral hiatus to the dural sac tip (needle distance). Subjects were F:M = 25:15, with a mean age of 44.9 years. The two S1-S5 full sacral curvature mean angles were 57.3° and 60.4°. Almost all sacral hiatuses were at S4, and dural sac terminations were at S1-S2. The mean S2-S4 sacral curvature was 25.1°, and the mean needle distance was 57.7 mm. Using two-way analysis of variance, there were significant sex differences for needle distances (p = .001), and full and limited sacral curvatures (p = .02, and p = .046, respectively). There were no significant linear regression correlations between age and sacral curvature, needle distance, canal area, or hiatus width. Therefore, despite a frequently prominent full sacral curvature, the combination of S1-S2 dural sac termination plus a relatively straight trajectory of the lower vertebral canal between S2 and S4 support the theoretical feasibility of percutaneous trans-sacral hiatus and vertebral canal access to the lumbosacral cistern using a standard spinal needle.

Factors predicting difficult spinal block: A single centre study.

BACKGROUND AND AIMS: Several factors determine the success of dural puncture. We aimed to assess the association of first puncture success and number of attempts with characteristics of the patient, provider, technique and equipment. MATERIAL AND METHODS: This prospective, observational study was performed in 1647 adult patients undergoing surgery under spinal anesthesia. Patient characteristics, anatomical landmarks, spinal bony deformity, provider experience, technique, skin punctures, needle redirections, subarachnoid space depth, and complications, if any, were noted. Difficult dural puncture was assessed by first puncture success and number of attempts (skin punctures plus needle redirections) required for successful needle placement. RESULTS: First puncture success was obtained in 872 (52.9%) patients. Failed dural puncture occurred in 4 (0.2%) of 1647 patients. Multivariate logistic regression analysis revealed that longer distance from C7 vertebral spine to tip of coccyx (P = 0.04), lower subarachnoid space depth (P = 0.001), good quality of bony landmarks (P = 0.001) and absence of crowded spine (P = 0.02) were associated with first puncture success. Male gender, poor or no spinal landmarks, presence of bony deformity and lower level of provider's experience predicted increased number of attempts for successful dural puncture. CONCLUSION: First puncture success of spinal block was influenced only by patient's anatomical factors, whereas the number of attempts required for successful block were predicted by both provider and patient factors.

Lower Glucose Level Associated With Increased Risk for Post-Dural Puncture Headache.

OBJECTIVE AND BACKGROUND: Post-dural puncture headache is the most common significant adverse event following lumbar puncture. In this study, we investigated the possible systemic factors associated with risk for post-dural puncture headache (PDPH). METHODS: We performed a retrospective cohort study in 969 patients who underwent diagnostic lumbar puncture following a standardized protocol. We compared the clinical and laboratory profiles of the post-dural puncture headache group and non-headache group. We also identified independent factors associated with the incidence of post-dural puncture headache. RESULTS: A total of 48 patients (5%) reported headache; 12 of these patients (25%) received a therapeutic epidural blood patch and the remaining 36 patients improved with conservative treatment. After adjusting for other variables that could be related to PDPH, we found that the development of post lumbar puncture headache was independently associated with age (OR: 0.97, 95% CI: 0.95-0.99, P = .001) and serum glucose levels (OR: 0.98, 95% CI: 0.97-0.99, P = .008).When the patients were classified by age, serum glucose levels were persistently lower in patients with PDPH vs those patients without PDPH in all age groups, with more clearly significant differences observed in the elderly (age <30 years, 103.4 mg/dL vs 106.3 mg/dL, P = .716; >60 years, 111.8 mg/dL vs 137.3 mg/dL, P = .023). CONCLUSIONS: Low glucose levels were inversely associated with risk for post-dural puncture headache. Patients with low serum glucose should be carefully monitored for headache after lumbar puncture.

Spectrophotometry of cerebrospinal fluid for xanthochromia is a sensitive and specific test for subarachnoid bleeding but adds little to computed tomography.

Subarachnoid hemorrhage (SAH) is a serious neurological event associated with high morbidity and mortality. Computed tomography of the cerebrum (CTC) is the diagnostic method of choice, but in case of negative CTC but strong suspicion of SAH, lumbar puncture with spectrophotometric analysis of cerebrospinal fluid (CSF) for xanthochromia is performed. We wanted to examine the diagnostic properties of CSF spectrophotometry for xanthochromia testing. We performed a retrospective study of the diagnostic properties of CSF analysis for xanthochromia using spectrophotometry in the diagnosis of SAH. A total of 489 CSF samples were analyzed for xanthochromia, according to international guidelines, from 2009 until 2014 and for 411 of these the patient files were retrieved and examined for final clinical diagnosis and result of CTC. One patient with SAH did not have a positive spectrophotometry report and another patient with SAH had an equivocal report. In four patients did initial CTC not correctly identify SAH. For patients with a negative CTC within six hours of symptom onset spectrophotometry for xanthochromia in the CSF had a diagnostic sensitivity of 100% and a diagnostic specificity of 98.5%. The positive predictive value was 16.7% and the negative predictive value 100%. We conclude that spectrophotometry of CSF for xanthochromia is a sensitive and specific test for diagnosing SAH. However, it seems that an initial CTC identifies almost all patients with SAH. This suggests that in our and similar diagnostic settings, lumbar puncture and testing for xanthochromia might only be relevant in very few cases, if not obsolete.

Magnetic resonance imaging anatomy and morphometry of lumbar intervertebral foramina to guide safe transforaminal subarachnoid punctures.

Percutaneous transforaminal lumbar punctures (TFLPs) offer alternative access routes to the lumbar subarachnoid cistern. Safe fluoroscopic insertion of a needle through a lumbar intervertebral foramen (IVF) should ideally avoid the exiting spinal nerve and surrounding vascular pedicles. A crescentic region in the posterior aspect of IVF is the conventional position for needle placement during TFLP, but the underlying anatomic basis for this has not been evaluated fully. To enhance TFLP safety, we defined the morphometry of normal lumbar IVFs and precise locations of neurovascular structures in the IVF posterior crescent. We retrospectively reviewed high-resolution T2-weighted lumbar spine magnetic resonance images of 40 normal adults to establish normative dimensions of each IVF from L1 to L5 bilaterally. We segmented the IVF posterior crescent into three parts, and within each, measured the areas occupied by neurovascular structures. We statistically correlated the presence or absence of neurovascular structures in each crescent segment using a chi-square test. The mean morphometrics for all 304 IVFs in 10 males and 30 females of similar ages were: area 115.3 ± 29.5 mm2 ; height 18.0 ± 2.4 mm; and width at mid-disc level 5.6 ± 2.1 mm. We found a significant association between crescent segment and presence or absence of neurovascular structures (χ2 = 95.9, p < .001). A post-hoc calculation of adjusted standardized residuals identified a significant association between the middle crescent segment and absence of neurovascular structures. Thus, the middle segment of the IVF posterior crescent is significantly most devoid of neurovascular structures, and more often would be the safest target for needle placement during TFLP.

Exploring the unknown territories in the new normal world of COVID.

It is now well known that the severe acute respiratory syndrome (SARS-CoV-2) originated in the Wuhan province of Hubei, China in 2019. Having spread across different countries of the world, this highly contagious disease has posed many challenges for the healthcare workers to work without endangering themselves and their patients' wellbeing. Several things are yet not clear about the virus and the presence or absence of the virus in the cerebrospinal fluid (CSF) is currently a debated topic. This article reports the perioperative management of two coronavirus disease-19 positive cases, one of whom was a pregnant patient. Their CSF samples, which were collected during the administration of spinal anesthesia, tested to be negative for viral reverse transcription polymerase chain reaction (RT-PCR) test. We wish to highlight from these cases, that during spinal anesthesia, CSF in mildly symptomatic COVID-19 cases probably does not pose a risk of transmission to the anesthesiologist. However, we suggest that due to the varied presentations of the virus, health care personnel, especially anesthesiologists have to be careful during the perioperative management of such cases.

Isolated cerebrospinal fluid hypertension in chronic headache: diagnostic innovations and clinical implications.

Isolated cerebrospinal fluid hypertension (ICH) is a condition of increased cerebrospinal fluid (CSF) pressure in the cranial-spinal compartment without an identifiable cause. Isolated headache is the most common symptom of ICH, while missing may be signs such as papilledema or sixth nerve palsy. This fact makes difficult the clinical diagnosis of headache attributable to ICH in headache sufferers. Another source of confusion stems from the CSF pressure measurement. It has been observed that a single-spot CSF opening pressure measurement may be insufficient to identify elevated CSF pressure in headache sufferers. A new method of CSF pressure measurement has been able to identify pressure-related features of isolated CSF hypertension (ICH). In fact, nocturnal or postural headache and abnormal pressure pulsations are the more common pressure-related features of ICH in patients with chronic headache. The compressive action of these abnormal pressure pulsations causes the periventricular white matter microstructure alterations leading to the focal diffusion tensor imaging findings in patients with ICH. Abnormal pressure pulsations are a marker of ICH in chronic headache. The identification of the CSF pressure-related features may be useful for differentiating headache sufferers with ICH from those with primary headache disorder in clinical practice. The therapeutic strategy in these headache sufferers with ICH includes the CSF removal and a medical treatment.

Can simulation-based education and precision teaching improve paediatric trainees' behavioural fluency in performing lumbar puncture? A pilot study.

BACKGROUND: Low levels of success in performing lumbar puncture have been observed among paediatric trainees. This study assessed the efficacy of simulation-based education with frequency building and precision teaching for training lumbar puncture to behavioural fluency. METHODS: The intervention group was assessed at baseline, at the final training trial, in the presence of distraction, and a minimum of one month after the cessation of the intervention in order to ascertain whether behavioural fluency in lumbar puncture was obtained. Subsequently, the performance of this intervention group (10 paediatric senior house officers) was compared to the performance of a comparator group of 10 more senior colleagues (paediatric registrars) who had not received the intervention. Retrospective chart audit was utilised to examine performance in the clinical setting. RESULTS: Intervention group participants required a mean of 5 trials to achieve fluency. Performance accuracy was significantly higher in the intervention group than the comparator group. Learning was retained at follow-up and persisted during distraction. Retrospective chart audit revealed no significant difference between the performance of the intervention group and a comparator group, comprised of more senior physicians, in the clinical setting, although the interpretation of these analyses are limited by a low number of lumbar punctures performed in the clinical setting. CONCLUSIONS: The programme of simulation-based education with frequency building and precision teaching delivered produced behavioural fluency in lumbar puncture among paediatric trainees. Following the intervention, the performance of these participants was equivalent to, or greater than, that of senior paediatricians. This study supports the need for further research exploring the effectiveness of simulation-based education with precision teaching to train procedural skills to fluency, and the consideration of how best to explore the impact of these on patient outcomes.

Are high lumbar punctures safe? A magnetic resonance imaging morphometric study of the conus medullaris.

A high lumbar puncture (LP) at L2-L3 or above is often necessary to consider on technical grounds, but complications of conus medullaris (CM) damage during high LP are potentially concerning. We hypothesized that a high LP might be safer than previously thought by accounting for movements of the CM upon patient positional changes. We retrospectively reviewed standard normal supine lumbar spine magnetic resonance imaging of 58 patients and used electronic calipers on axial images at the T12-L1, L1-L2, and L2-L3 disc levels to measure the transverse diameter of the CM relative to the size of the dorsal thecal sac space (DTSS) through which a spinal needle could be inserted. On 142 axial images, the means for CM diameters were 8.2, 6.0, and 2.9 mm at the three levels, respectively. We then used known literature mean CM displacement values in the legs flexed and unflexed lateral decubitus position (LDP) to factor in CM shifts to the dependent side. We found that at all three levels, the likely positional shift of the CM would be too small and insufficient to displace the entire CM out of the DTSS. However, if needle placement could be confined to the midsagittal plane, an LP in the unflexed LDP would theoretically be entirely safe at both L1-L2 and L2-L3, and almost so at L2-L3 in the legs flexed LDP. Thus, high LPs at L1-L2 and L2-L3 are in theory likely safer than considered previously, more so in the legs unflexed than in the flexed LDP. Clin. Anat. 32:618-629, 2019. © 2019 Wiley Periodicals, Inc.

Effect of spinal needle characteristics on measurement of spinal canal opening pressure.

OBJECTIVE: A wide variety of spinal needles are used in clinical practice. Little is currently known regarding the impact of needle length, gauge, and tip type on the needle's ability to measure spinal canal opening pressure. This study aimed to investigate the relationship between these factors and the opening-pressure measurement or time to obtain an opening pressure. METHODS: Thirteen distinct spinal needles, chosen to isolate the effects of length, gauge, and needle-point type, were prospectively tested on a lumbar puncture simulator. The key outcomes were the opening-pressure measurement and the time required to obtain that measure. Pressures were recorded at 10-s intervals until 3 consecutive, identical readings were observed. RESULTS: Time to measure opening pressure increased with increasing spinal needle length, increasing gauge, and the Quincke-type (cutting) point (P<0.001 for all). The time to measurement ranged from 30s to 530s, yet all needle types were able to obtain a consistent opening pressure measure. CONCLUSION: Although opening pressure estimates are unlikely to vary markedly by needle type, the time required to obtain the measurement increased with increasing needle length and gauge and with Quincke-type needles.

Instrumented gait analysis for an objective pre-/postassessment of tap test in normal pressure hydrocephalus.

OBJECTIVE: To present an objective method to evaluate gait improvements after a tap test in idiopathic normal pressure hydrocephalus (INPH). DESIGN: Retrospective analysis of gait data. SETTING: Public tertiary care center, day hospital. The gait analysis was performed before and 2 to 4 hours after the tap test. PARTICIPANTS: Participants included patients with INPH (n=60) and age- and sex-matched controls (n=50; used to obtain reference intervals). From an initial referred sample of 79 patients (N=79), we excluded those unable to walk without walking aids (n=9) and those with incomplete (pre-/posttap test) gait data (n=10). Thirteen out of 60 patients were shunted and then reappraised after 6 months. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Mahalanobis distance from controls, before and after the tap test. Eleven gait parameters were combined in a single quantitative score. Walking velocity was also evaluated because it is frequently used in tap test assessment. RESULTS: Patients were classified into 2 groups: tap test responders (n=22, 9 of them were shunted) and not suitable for shunt (n=38, 4 of them were shunted). In the tap test responders group, 9 out of 9 patients improved after shunt. In the not suitable for shunt group, 3 out of 4 patients did not improve. Gait velocity increased after the tap test in 53% of responders and in 37% of patients not suitable for shunt. CONCLUSIONS: The new method is applicable to clinical practice and allows for selecting tap test responders in an objective way, quantifying the improvements. Our results suggest that gait velocity alone is not sufficient to reliably assess tap test effects.