Sagittal balance parameters in achondroplasia

Introduction

Lumbar spinal stenosis (LSS) is the main problem for adult achondroplasia (Ach). Sagittal imbalance of the spine may play a role in LSS causing neurogenic claudication in Ach patients.

Research question

The purpose of this study is to describe the sagittal balance parameters in Ach patients.

Methods

A single-centre retrospective study of Ach patients that visited the Neurosurgery outpatient clinic of the Leiden University Medical Centre (LUMC) between 2019 and 2022 was performed. We defined sagittal imbalance by a C7 sagittal vertical axis (SVA) of more than 10 mm.

Results

There were 13 patients with a spinal sagittal imbalance and 15 patients with a balanced spine. In both groups, the sacral slope (SS) was comparable (45.0° and 49.0°, p = 0.305), but exceeding the mean SS in non achondroplasts (38.0°). Lumbar lordosis (LL) was more pronounced in the balanced group (55.5° versus 41.7°, p = 0.019), and positively correlated to SS in contrast to the absence of a correlation in the imbalanced group. Thoracolumbar kyphosis (TLK) was increased comparably in both groups (19.6° and 24.6°), and far exceeding the TLK in non achondroplasts (circa 0°), and in both groups negatively correlated with the LL, although not enough to compensate for the smaller LL in the imbalanced group.

Conclusion

Only if the LL compensates for both a larger SS and TLK, the Ach spine can maintain sagittal balance. An explanation for the current data can be the failure of the lumbar spine to give sufficient lordosis due to degenerative processes.

Association Between Radiological Severity of Lumbar Spinal Stenosis and Spinopelvic Parameters in Adult Patients With Achondroplasia

BACKGROUND AND OBJECTIVES

Adults with achondroplasia are more vulnerable to suffer from neurogenic claudication because of a congenital narrow spinal canal, which makes them susceptible to lumbar spinal stenosis (LSS). The study aims to investigate the correlations between sagittal alignment parameters and the degree of LSS in patients with achondroplasia with LSS.

METHODS

The radiological data of adult achondroplasts presented to the neurosurgical clinic of our medical center from 2019 to 2022 were collected. Lumbar stenosis was graded using the Schizas scale, and the dural sac cross-sectional area (DSCA) was measured. The angles defining the spinopelvic parameters comprising lumbar lordosis, thoracolumbar kyphosis, sagittal vertical axis, pelvic tilt, sacral slope, and pelvic incidence were measured. Spearman or Pearson correlation was used to investigate the association between sagittal misalignment and LSS.

RESULTS

A total of 34 achondroplastics were enrolled, with a median age of 44.3 ± 15.5 years, ranging from 18.6 to 78.5 years. Larger thoracolumbar kyphosis was associated with more severe stenosis according to the Schizas scale of the L 12 lumbar level (r = 0.44, P = .020, 95% CI [0.08, 0.70]). Larger sagittal vertical axis correlated with a smaller DSCA at L 23 (r = -0.53, P = .036, 95% CI [-0.81, -0.04]) and L 45 (r = -0.66, P = .004, 95% CI [-0.87, -0.26]). Larger pelvic tilt was demonstrated to be associated with a smaller DSCA of the L 34 lumbar level (r = -0.42, P = .027, 95% CI [-0.68, -0.05]) and the L 45 lumbar level (r = -0.47, P = .011, 95% CI [-0.71, -0.12]).

CONCLUSION

The upper LSS may be attributed to an increased kyphosis of the thoracolumbar spine. On the contrary, the lower LSS seemed to be correlated with a more backward tilt of the pelvis.

Dural Venous Sinus Thrombosis After Vestibular Schwannoma Surgery: Should We Anticoagulate?

BACKGROUND

The incidence of dural venous sinus thrombosis (DVST) following vestibular schwannoma (VS) surgery remains understudied. The diverse clinical presentation complicates forming anticoagulation treatment guidelines. This meta-analysis aimed to investigate the incidence of DVST post-VS surgery and to evaluate the role of anticoagulation.

METHODS

A systematic review, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist, was conducted. Studies reporting DVST incidence after VS surgery were included. DVST incidence stratified by detection method was the primary outcome. Adverse events per treatment strategy (anticoagulation or no anticoagulation) were the secondary outcome. Pooled incidence with respective 95% confidence intervals were calculated using the random-effects model via the DerSimonian and Laird method.

RESULTS

The overall DVST incidence post-VS resection was 15.5% (95% confidence interval: 10.3%, 22.5%; 10 studies). Stratification by detection method revealed 29.4% (19.2%, 42.3%) for magnetic resonance imaging, 8.2% (3.2%, 19.5%) for computed tomography, and 0.7% (0.2%, 2.8%) upon clinical suspicion. The pooled incidence of adverse events was 16.1% (6.4%, 35.0%) for the anticoagulation treatment and 4.4% (1.4%, 12.9%) for no anticoagulation treatment, with one mortality case being among the adverse events in this latter group.

CONCLUSIONS

DVST after VS surgery is more common than initially perceived, predominantly presenting asymptomatically. Variability in anticoagulation protocols hinders the establishment of definitive therapeutic stances; nevertheless, there is no supporting evidence to promote anticoagulation administration for DVST. This begs the need for further institutional comparative studies with a proper adjustment for confounding and well-defined anticoagulation regimens.

Early evaluation and treatment of thoracolumbar kyphosis in children with achondroplasia

PURPOSE

Thoracolumbar kyphosis (TLK) is frequently reported in children with achondroplasia. The combination of TLK and the narrow spinal canal in achondroplasia increases the risk of developing symptomatic spinal stenosis. However, there is no consensus on the optimal management of TLK.

METHODS

This retrospective cohort study evaluated children under four years old with achondroplasia, monitoring TLK every six months. Pathologic TLK was defined as a Cobb angle of 20 degrees or more between T10 and L2. Management involved either a wait-and-see policy, which prohibited unsupported sitting, or bracing. Surgery was reserved for severe progressive TLK or spinal stenosis cases. TLK was evaluated over time. A receiver operating characteristic curve determined the baseline threshold where wait-and-see management failed to resolve TLK below 20 degrees. Multiple linear regression compared bracing versus wait-and-see management for cases exceeding 40 degrees.

RESULTS

Sixty-two patients were included, with a median age of 10 months and a median follow-up of 31 months. TLK prevalence decreased from 85% at baseline to 42% at final follow-up. The mean Cobb angle decreased from 31 ± 11 degrees to 22 ± 16 degrees (p < 0.001). The threshold for ineffective wait-and-see management was identified as 33 degrees. Bracing resulted in significantly more TLK reduction than wait-and-see management for cases exceeding 40 degrees (15 degree difference, 95% CI 2-28, p = 0.023). Three patients required surgery.

CONCLUSION

TLK is highly prevalent in achondroplasia, necessitating careful monitoring. A wait-and-see policy with restrictions on unsupported sitting is recommended initially, but early bracing should be considered for more severe cases.

SAFETY OF NON-OSSEOUS UNION OF TYPE II ODONTOID FRACTURES - A MULTI-INSTITUTIONAL COHORT STUDY

BACKGROUND CONTEXT

The management of type II odontoid fractures in elderly patients presents significant clinical challenges. Surgical treatment may lead to operative complications, while conservative management may increase the risk of non-osseous union, potentially compromising fracture stability.

PURPOSE

This study aims to evaluate the safety of non-osseous union subtypes in type II odontoid fractures following conservative treatment and to identify risk factors for unstable fractures.

STUDY DESIGN

A multi-institutional retrospective cohort study.

PATIENT SAMPLE

A total of 307 patients with acute type II odontoid fractures treated conservatively between 2005 and 2022 were included. The mean age was 76 ± 17 years, with a median follow-up of 24 months (IQR 9 - 55 months).

OUTCOME MEASURES

Fracture healing and stability were assessed. Safety of each healing subtype was determined by the incidence of new neurological deficits post-collar removal or the need for surgical fixation. Risk factors for unstable fractures were also determined.

METHODS

Fracture healing was classified as osseous union, fibrous non-union, or unstable non-union based on CT and dynamic X-rays at collar removal. Fracture stability was assessed using only dynamic X-rays, with unstable fractures demonstrating active displacement. Neurological outcomes and the necessity for surgical fixation in each group were compared. Multivariable logistic regression was used to analyze risk factors for fracture instability.

RESULTS

Unstable non-union occurred in 25% of patients, while fibrous non-union occurred in 47% after a median collar wear of 3.7 months (IQR 2.9 - 6.2 months). New neurological deficits after collar removal were seen in 6% of patients with unstable non-unions during follow-up, but in none of those with fibrous non-unions or osseous unions, even after subsequent trauma. Risk factors for unstable non-union included male sex (OR 2.14; 95% CI: 1.02-4.49), osteoporosis/osteopenia (OR 2.50; 95% CI: 1.17- 5.37), and baseline fracture displacement (OR 4.81; 95% CI: 2.35-9.86).

CONCLUSIONS

Fibrous non-union is a viable outcome in conservatively managed type II odontoid fractures, reducing the need for surgery or prolonged collar wear. Risk factors for unstable non-union included male sex, osteoporosis/osteopenia, and baseline fracture displacement. Unstable non-unions may lead to new neurological deficits occurring post-collar removal in a small percentage of cases.

Improved Generalizability in Medical Computer Vision: Hyperbolic Deep Learning in Multi-Modality Neuroimaging

Deep learning has shown significant value in automating radiological diagnostics but can be limited by a lack of generalizability to external datasets. Leveraging the geometric principles of non-Euclidean space, certain geometric deep learning approaches may offer an alternative means of improving model generalizability. This study investigates the potential advantages of hyperbolic convolutional neural networks (HCNNs) over traditional convolutional neural networks (CNNs) in neuroimaging tasks. We conducted a comparative analysis of HCNNs and CNNs across various medical imaging modalities and diseases, with a focus on a compiled multi-modality neuroimaging dataset. The models were assessed for their performance parity, robustness to adversarial attacks, semantic organization of embedding spaces, and generalizability. Zero-shot evaluations were also performed with ischemic stroke non-contrast CT images. HCNNs matched CNNs' performance in less complex settings and demonstrated superior semantic organization and robustness to adversarial attacks. While HCNNs equaled CNNs in out-of-sample datasets identifying Alzheimer's disease, in zero-shot evaluations, HCNNs outperformed CNNs and radiologists. HCNNs deliver enhanced robustness and organization in neuroimaging data. This likely underlies why, while HCNNs perform similarly to CNNs with respect to in-sample tasks, they confer improved generalizability. Nevertheless, HCNNs encounter efficiency and performance challenges with larger, complex datasets. These limitations underline the need for further optimization of HCNN architectures. HCNNs present promising improvements in generalizability and resilience for medical imaging applications, particularly in neuroimaging. Despite facing challenges with larger datasets, HCNNs enhance performance under adversarial conditions and offer better semantic organization, suggesting valuable potential in generalizable deep learning models in medical imaging and neuroimaging diagnostics.

Prevalence and natural development of thoracolumbar kyphosis in achondroplasia: A systematic review and meta-analysis

Introduction

Thoracolumbar kyphosis (TLK) is a frequently reported spinal deformity in achondroplasia, which in combination with the characteristic narrow spinal canal in achondroplasia predisposes for symptomatic spinal stenosis. There is however no consensus on the optimal treatment, due to limited data on diagnostic criteria, the natural development and the prevalence of TLK.

Research question

This study aims to assess the prevalence, natural development, and diagnostic criteria for pathological TLK in individuals with achondroplasia.

Material and methods

A systematic review and meta-analysis were conducted. Studies involving achondroplasia patients, which reported TLK measurement methods were included. The primary outcome was the pooled prevalence of TLK, stratified by age.

Results

Eight studies, encompassing 852 patients, met the inclusion criteria. Pathological TLK was most frequently defined as a Cobb angle of 20° or greater, between T10 and L2. TLK was present in 87% (95% CI 80%-91%) of patients under two years old, decreasing to 33% (24%-43%) at age three, 26% (19%-35%) between five and ten years, and 23% (16%-31%) in patients aged 10-20 years.

Discussion and conclusion

Pathological TLK in achondroplasia, defined as a Cobb angle of 20° or greater, appears primarily in early childhood and often resolves by walking age. However, approximately one-fourth of cases persist into adulthood, with factors such as developmental motor delay and vertebral wedging contributing to this persistence. Routine clinical and radiological evaluations during childhood, along with conservative management, are recommended to mitigate the need for surgery during adulthood.

A multicenter study of clinical outcomes and volumetric trends in suspected microprolactinomas

The diagnosis of pituitary microprolactinomas is often obscured by relatively low levels of elevated prolactin compared to macroprolactinomas. This may lead to varying patterns of medical therapy versus observation. We sought to correlate prolactin levels in suspected microprolactinomas with tumor volumes and clinical outcomes. This was a multicenter retrospective study of patients with pituitary microadenomas with baseline prolactin levels > 18ng/ml for males and > 30ng/ml for females. A linear-mixed model was used to depict changes in tumor volume over time. There were 65 patients with a mean tumor volume of 95.9mm3 and mean prolactin level of 59.4ng/ml. There were significantly higher prolactin levels in patients with tumors above the mean volume versus below (74.0 versus 53.4ng/ml, p = 0.027). 26 patients were observed, 31 were treated with anti-dopaminergic therapy, and 8 had surgery. There were significantly greater baseline prolactin levels for patients who were treated surgically (mean 86.4ng/ml) than those treated medically (mean 61.7 g/ml) or observed (mean 48.5ng/ml) (p = 0.02). Among the 26 patients who were surveilled, 13 patients demonstrated spontaneous tumor shrinkage, 12 remained stable, and 1 patient's tumor grew but was lost to follow-up. Linear mixed modeling demonstrated a statistically significant rate of tumor shrinkage over time of 3.67mm3/year (p = 0.03). When analyzing patients who were observed versus those requiring surgery after initially being surveilled, there were significantly greater baseline PRL/volume ratios in surgical patients versus those observed (8.1 ng/ml/mm3 versus 2.4 ng/ml/mm3, p = 0.025). Suspected microprolactinomas may demonstrate more convincingly elevated prolactin levels when measuring over 95.9mm3. Tumors with baseline prolactin levels over 50ng/ml may be more inclined to undergo medical treatment. In tumors with levels below 50ng/ml, it may be reasonable to undergo surveillance as these tumors tend to spontaneously shrink over time. In tumors that are surveilled, an elevated baseline PRL/volume ratio of > 8 ng/ml/mm3 may be indicate serial tumor growth that may necessitate medical and/or surgical intervention.

The utility of the 5-Item frailty index in assessing the risk of complications and mortality following surgical management of non-traumatic subarachnoid hemorrhage

The modified 5-item frailty index (mFI-5), an index of reduced physiological reserve, has risen as a predictor of complications following surgical procedures. We examined the association of mFI-5 and surgical outcomes following the management of nontraumatic subarachnoid hemorrhage (nSAH). We queried the American College of Surgeons National Surgical Quality Improvement Program database for patients who received surgical management of nSAH between 2006 and 2021. We computed the mFI-5 by granting a point for each of 1) congestive heart failure, 2) hypertension requiring medications, 3) diabetes, 4) chronic obstructive pulmonary disease or pneumonia within 30 days before surgery, and 5) dependent functional status. Our 30-day endpoints were minor complications (Clavien-Dindo: 1 & 2), major complications (Clavien-Dindo: 3 & 4), and mortality. Using the Chi-squared test, we compared baseline patient demographics and comorbidities between patients with a mFI-5 ≥ 2, patients with a mFI-5 = 1, and non-frail patients. Then, we fitted a multivariable logistic regression adjusting for patient demographics, comorbidities, operative time, and frailty status. The cohort included 1,139 patients, of which 33.7 % were men and 2.9 % had a bleeding diathesis. After adjusting for covariates, mFI-5 ≥ 2 was independently associated with minor complications (1.93, 95 %CI: 1.31-2.84, p = 0.001), major complications (aOR: 1.62, 95 %CI: 1.10-2.37, p = 0.015), and mortality (aOR: 2.90, 95 %CI: 1.66-5.08, p = 0.003). The mFI-5 can be independently used by surgeons for risk stratification and postoperative planning.