Perils and pitfalls of lumbar puncture in the emergency department

Noninvasive methods to monitor intracranial pressure

PURPOSE OF REVIEW

Intracranial pressure (ICP) is determined by the production of and outflow facility of cerebrospinal fluid. Since alterations in ICP are implicated in several vision-threatening and life-threatening diseases, measurement of ICP is necessary and common. All current clinical methods to measure ICP are invasive and carry the risk for significant side effects. Therefore, the development of accurate, reliable, objective, and portal noninvasive devices to measure ICP has the potential to change the practice of medicine. This review discusses recent advances and barriers to the clinical implementation of noninvasive devices to determine ICP.

RECENT FINDINGS

Many noninvasive methods to determine ICP have been developed. Although most have significant limitations limiting their clinical utility, several noninvasive methods have shown strong correlations with invasively obtained ICP and have excellent potential to be developed further to accurately quantify ICP and ICP changes.

SUMMARY

Although invasive methods remain the mainstay for ICP determination and monitoring, several noninvasive biomarkers have shown promise to quantitatively assess and monitor ICP. With further refinement and advancement of these techniques, it is highly possible that noninvasive methods will become more commonplace and may complement or even supplant invasively obtained methods to determine ICP in certain situations.

Using near-infrared spectroscopy and a random forest regressor to estimate intracranial pressure

SIGNIFICANCE

Intracranial pressure (ICP) measurements are important for patient treatment but are invasive and prone to complications. Noninvasive ICP monitoring methods exist, but they suffer from poor accuracy, lack of generalizability, or high cost.

AIM

We previously showed that cerebral blood flow (CBF) cardiac waveforms measured with diffuse correlation spectroscopy can be used for noninvasive ICP monitoring. Here we extend the approach to cardiac waveforms measured with near-infrared spectroscopy (NIRS).

APPROACH

Changes in hemoglobin concentrations were measured in eight nonhuman primates, in addition to invasive ICP, arterial blood pressure, and CBF changes. Features of average cardiac waveforms in hemoglobin and CBF signals were used to train a random forest (RF) regressor.

RESULTS

The RF regressor achieves a cross-validated ICP estimation of 0.937 r 2 , 2.703 - mm Hg 2 mean squared error (MSE), and 95% confidence interval (CI) of [ - 3.064    3.160 ]    mmHg on oxyhemoglobin concentration changes; 0.946 r 2 , 2.301 - mmHg 2 MSE, and 95% CI of [ - 2.841    2.866 ]    mmHg on total hemoglobin concentration changes; and 0.963 r 2 , 1.688    mmHg 2 MSE, and 95% CI of [ - 2.450    2.397 ]    mmHg on CBF changes.

CONCLUSIONS

This study provides a proof of concept for the use of NIRS in noninvasive ICP estimation.

Computed Tomography-Guided Lumbar Puncture: Advantages and Disadvantages

OBJECTIVE

This study aimed to evaluate the utility of computed tomography (CT) guidance in difficult lumbar puncture (LP) cases, which had a history of at least one unsuccessful blind attempt at LP (no imaging guidance), and to note potential advantages and disadvantages of the use of CT guidance.

METHODS

In total, 32 CT-guided LP procedures performed between June 2019 and March 2021 were included. All LP indications were recorded. The procedures where the cerebrospinal fluid flow was provided by a single puncture were evaluated as "primary technical success." "Secondary technical success" corresponded with the procedures in which additional puncture was necessary for the cerebrospinal fluid flow.

RESULTS

Intrathecal nusinersen injections due to spinal muscular atrophy constituted the largest procedure group of this study. Among 32 procedures, primary and secondary technical success rates were 78.12% and 28.57%, respectively. There were no major procedural complications.

CONCLUSIONS

Computed tomography-guided LP is an effective interventional technique offering an alternative approach in the setting of difficult LP procedures.

Primary Central Nervous System Leukemia Presenting as Altered Mental Status

BACKGROUND

Altered mental status is a common cause for presentation to the emergency department with a broad differential diagnosis.

CASE REPORT

We present a unique case of altered mental status in a previously healthy man that was found to be secondary to primary central nervous system acute lymphoblastic leukemia. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Lumbar puncture remains a critical tool for emergency physicians in the diagnosis of central nervous system pathologies.

Detection and characterization of tree shrew retinal venous pulsations: An animal model to study human retinal venous pulsations

Spontaneous retinal venous pulsations (SRVPs), pulsations of branches of the central retinal vein, are affected by intraocular pressure (IOP) and intracranial pressure (ICP) and thus convey potentially-useful information about ICP. However, the exact relationship between SRVPs, IOP, and ICP is unknown. It is not easily feasible to study this relationship in humans, necessitating the use of an animal model. We here propose tree shrews as a suitable animal model to study the complex relationship between SRVPs, IOP, and ICP. Tree shrew SRVP incidence was determined in a population of animals. Following validation of a modified IOP control system to accurately and quickly control IOP, IOP and/or ICP were manipulated in two tree shrews with SRVPs and the effects on SRVP properties were quantified. SRVPs were present in 75% of tree shrews at physiologic IOP and ICP. Altering IOP or ICP produced changes in tree shrew SRVP properties; specifically, increasing IOP caused SRVP amplitude to increase, while increasing ICP caused SRVP amplitude to decrease. In addition, a higher IOP was necessary to generate SRVPs at a higher ICP than at a lower ICP. SRVPs occur with a similar incidence in tree shrews as in humans, and tree shrew SRVPs are affected by changes in IOP and ICP in a manner qualitatively similar to that reported in humans. In view of anatomic similarities, tree shrews are a promising animal model system to further study the complex relationship between SRVPs, IOP, and ICP.

A Web-based Decision Tool to Estimate Subarachnoid Hemorrhage Risk in Emergency Department Patients

Subarachnoid hemorrhage (SAH) from a leaking aneurysm is a neurological emergency. SAH patients often present with headache-a common chief complaint among emergency department patients. If unrecognized, 70% of the patients with re-bleeds die and one third are left with neurological deficits. Therefore, it is critical to distinguish the signs and symptoms of SAH from benign causes of headache, perform the appropriate diagnostic tests and treat in a timely manner in order to reduce the disability and mortality associated with this condition. In patients with suspected SAH, traditional diagnostic strategies in the emergency department employ non-contrast computed tomography (CT) of the brain to detect blood in the subarachnoid space followed by lumbar puncture if there is a high clinical probability of aneurysmal bleed without any evidence of blood on CT scan. While the older generation CT scanners were less sensitive to blood detection in the subarachnoid space, recent advances in CT imaging have resulted in sensitivity approaching 100% for detection of blood in the subarachnoid space specifically within six hours of symptom onset. Therefore, the benefit of lumbar puncture is controversial when performed within the first six hours of symptom onset. Despite this, lumbar puncture is still commonly performed in the emergency department, exposing patients to unnecessary procedural risks. The objective of this research study is to develop a web-based risk calculator that estimates the risk of SAH based on time to emergency department presentation after symptom onset, physical findings and imaging characteristics with the goal of reducing unnecessary lumbar punctures in the emergency department. In this technical report, we describe the prototype calculator, the mathematical basis of the model and provide a link to the web-based prototype. In the future, we will refine the prototype, make it user-friendly to physicians, staff and patients and study its benefits in the emergency department.

Non-puerperal uterine inversion in a patient with intracranial sigmoid sinus thrombosis and facial palsy

Non-puerperal uterine inversion and cranial nerve palsies in patients with sigmoid sinus thrombosis are both extremely rare. We report a case of a patient who presented with both simultaneously. The symptoms of sigmoid sinus thrombosis resolved with subcutaneous enoxaparin, and an abdominal dissection with removal of the uterus vaginally resulted in a successful outcome for the patient.

Multidetector CT-Guided Lumbar Puncture in Patients with Cancer

SUMMARY

Lumbar puncture can be performed for therapeutic purposes, to instill intrathecal chemotherapy for leptomeningeal cancer treatment or prophylaxis. This technique is generally performed blindly or under fluoroscopic guidance. However, in certain situations, lumbar puncture using multidetector CT (MDCT)-guided imaging may be beneficial, when other options have been exhausted or depending on the requirements of the performing radiologist's institution. The purpose of this article is to describe the technique and to evaluate outcomes of MDCT-guided lumber puncture for diagnostic and therapeutic purposes in patients with cancer. We conclude that MDCT-guided lumbar puncture is an effective and safe guiding modality for thecal sac access in patients with cancer, particularly where other methods of intrathecal access have failed.

Ultrasound-assisted collection of cerebrospinal fluid from the lumbosacral space in equids

OBJECTIVE

To describe ultrasonographic landmarks for use in collection of CSF from the lumbosacral region in equids.

DESIGN

Prospective study.

ANIMALS

37 equids (27 with neurologic disease and 10 with nonneurologic disease).

PROCEDURES

Standing equids (n = 17) were sedated with detomidine hydrochloride (0.006 to 0.01 mg/kg [0.003 to 0.005 mg/lb], IV) followed by butorphanol tartrate (0.01 mg/kg, IV) and restrained with a nose twitch for collection of CSF. The CSF was collected from 20 laterally recumbent equids (10 sedated and 10 immediately after euthanasia). Anatomic landmarks were identified ultrasonographically. Height at the dorsal point of the shoulders, body weight, depth of the spinal needle, number of attempts to collect CSF, and cytologic evaluation of CSF were recorded.

RESULTS

Lumbosacral puncture cranial to the cranial border of the most superficial location of both tuber sacrale along the midline was consistently successful for CSF collection (35/37 equids). Two horses had anatomic abnormalities that precluded CSF collection. Mean number of attempts to collect CSF per animal was 1.1. Height and body weight were strongly correlated with needle depth for CSF collection. Pelvic and sacral displacement was observed in several laterally recumbent animals, which resulted in discrepancies of the midline between the cranial and caudal aspects of the vertebral column. In most equids, the spinal needle was aligned on the midline of the caudal aspect of the vertebral column.

CONCLUSIONS AND CLINICAL RELEVANCE

Ultrasonography was a useful aid for collection of CSF from the lumbosacral space and decreased the risk of repeated trauma and contamination in equids.

The use of ultrasound to identify pertinent landmarks for lumbar puncture

OBJECTIVE

This study was conducted to assess the ultrasound's (US's) ability to identify pertinent landmarks for lumbar puncture (LP) in patients of various body mass indices (BMIs) and establish spatial relationships of pertinent LP landmarks across BMIs.

METHODS

In this institutional review board-approved cross-sectional study, we calculated the BMIs of eligible patients and then categorized them as normal (BMI < or =24.9), overweight (BMI 24.9-30), or obese (BMI > or =30). We recorded the difficulty in palpating traditional LP landmarks. Identification and measurement of the spatial relationships of the sacrum; spinous processes of lumbar vertebrae L3, L4, and L5; ligamentum flavum; and the spinal canal by US was attempted.

RESULTS

Successful identification of pertinent structures (L4-L5 spinous processes and the spinal canal) occurred in 100% of patients with normal BMI, 95% of those who were overweight, and 74% of those who were obese (P = .011). Difficulty in palpating landmarks was noted in 5% of patients with normal BMI, 33% of those who were overweight, and 68% of those who were obese (P < .0001). In subjects with difficult-to-palpate landmarks, US identified pertinent structures in 16 of 21 (76%; 95% confidence interval, 53-92). The average distance from skin to ligamentum flavum was 44 mm in those with normal BMI, 51 mm in those who were overweight, and 64 mm in those who were obese (P < .00001); measurements between spinous processes did not vary by BMI. Overall, there was a moderate correlation (0.62) between BMI and the distance from skin to ligamentum flavum.

CONCLUSION

The usefulness of US in identifying structures for LP is inversely related to BMI. Even with this limitation, US is still able to identify obese patients' pertinent landmarks almost 75% of the time. In addition, US may be helpful in identifying pertinent structures for LP in those patients with difficult-to-palpate landmarks. In patients who were obese with structures not palpable by hand or identifiable by US, other modalities should be considered.

Questioning the need for routine bone marrow aspiration and lumbar puncture in patients with retinoblastoma

PURPOSE

This study assesses the value of routinely investigating children with retinoblastoma with bone marrow aspiration and lumbar puncture, staging investigations not without risk and trauma to the patient, emotional stress on parents and financial cost to the community.

METHODS

Medical files and specimens were obtained and examined for patients with retinoblastoma presenting to the Royal Alexandra Hospital for Children, Camperdown and the Children's Hospital at Westmead, Sydney, from 1975 to 2001.

RESULTS

In total, 123 patients presented; 62 (50.4%) were boys and 61 (49.6%) were girls. Of these 123 patients, 74 (60.2%) had unilateral disease, 46 (37.4%) involving the left eye and 28 (22.8%) involving the right eye. There were 47 (38.2%) patients with bilateral disease, and two (1.6%) with trilateral disease. Mean age of presentation was 17.9 months (23.1 months for unilateral subjects; 10.3 months for bi-lateral subjects; 3.5 months for trilateral subjects). There were 13 (10.6%) with a positive family history. Of 74 unilateral subjects, 70 (94.6%) required enucleation and four (5.4%) were salvaged. Of 47 bilateral subjects, 13 (27.7%) did not require enucleation, 27 (57.4%) required unilateral enucleation and seven (14.9%) required bilateral enucleation. Both trilateral subjects died. Of all 123 subjects, 112 (91.1%) had bone marrow aspiration and lumbar puncture performed during initial assessment, and none showed evidence of malignancy.

CONCLUSIONS

Given the small but significant risks associated with these procedures, the results of this study cannot support bone marrow aspiration and lumbar puncture as routine investigations in all patients presenting with retinoblastoma, suggesting a more limited usage of these investigations is warranted.