Month: July 2026

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The Mastoid Foramen and Mastoid Emissary Vein Canal as Surgical Landmarks for Mastoid Pneumatization During Retrosigmoid Approach

Operative Neurosurgery 31:74–84, 2026

This study investigates the anatomical, radiological, and intraoperative relationships between the mastoid foramen (MF), mastoid emissary vein canal (MEVC), and mastoid air cell (MAC) pneumatization to improve planning and safety of the retrosigmoid approach (RSA). It reports measurements from cadaveric specimens, high-resolution CT of 100 patients, and surgical outcomes from 54 RSA procedures, linking MF/MEVC positions with pneumatization grades.

Key findings show the MF and MEVC are reliably posterior to MACs in most cases, with higher pneumatization grades correlated with shorter MF‑MAC and mMEVC‑MAC distances. Preoperative radiological assessment of these landmarks guided burr hole placement and border‑sealing techniques, reducing intraoperative MAC openings and postoperative complications.

Goal Assess whether the mastoid foramen (MF) and mastoid emissary vein canal (MEVC) can predict mastoid pneumatization and guide safer retrosigmoid approach (RSA) craniectomy planning.

Methods Combined anatomic dissection/drilling (2 dry temporal bones; 2 formalin-fixed heads), radiology (100 high‑resolution CTs; Han grade 1–4), and surgical review (54 RSA cases with complication tracking).

Classification & measures MF labeled “posterior” vs “anterior” to the most posterior mastoid air cell (MAC); MEVC labeled type 1 (posterior to MACs) vs type 2 (within MACs); quantified MF‑MAC distance and minimal MEVC‑MAC (mMEVC‑MAC) distance.

Key anatomy pattern MF was posterior to MACs in 99.4% of CT sides; MEVC was posterior to MACs in 88.0% (i.e., type 2 “within MACs” in the remainder).

Pneumatization relationships Higher Han pneumatization grades were associated with shorter MF‑MAC and mMEVC‑MAC distances (both P < .001), and these two distances were strongly correlated (r = 0.741, P < .001).

Age association Mastoid pneumatization grade decreased with age (inverse correlation, P < .001).

Surgical risk signal Intraoperative MAC opening occurred in 5.6% (3/54), and all had Han grade 4 pneumatization with type 2 MEVC (“within” MACs).

Clinical outcome No major intraoperative complications were reported; only one CSF wound leak (1.9%) occurred postoperatively and resolved with lumbar drainage.

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Safety and Efficacy of Real-Time Intraoperative Ultrasound-Guided Posterolateral Thoracic Diskectomy

Operative Neurosurgery 31:20–27, 2026

This article reports a single-center retrospective case series evaluating real-time intraoperative ultrasound (IOUS)-guided posterolateral thoracic diskectomy for symptomatic thoracic disk herniation (TDH). The study of 32 patients (41 levels) demonstrates significant reductions in pain and Nurick scores, low blood loss, moderate operative times, no postoperative complications, and high fusion rates at follow-up.

The manuscript details patient selection, surgical technique using IOUS for direct ventral cord visualization during posterolateral diskectomy, perioperative outcomes, and limitations. Authors conclude IOUS-guided posterolateral diskectomy is a safe, effective, and broadly adoptable method that improves decompression while minimizing morbidity compared with traditional anterior or lateral approaches.

Clinical problem: Thoracic disk herniation surgery is technically challenging because the thoracic canal is narrow and the spinal cord blocks direct access/visualization of ventral pathology.

Technique: Real-time intraoperative ultrasound (IOUS) is used during a posterolateral thoracic diskectomy to directly visualize the spinal cord and TDH, guide instrument positioning, and confirm decompression intraoperatively.

Study design: Retrospective single-surgeon series of symptomatic TDH patients treated with IOUS-guided posterolateral diskectomy from May 2020 to Feb 2025 at a major academic center.

Cohort details: 32 patients (41 levels); 50% had calcified disks (n=16), predominantly central lesions (n=13), including 2 “giant” TDHs (>40% canal).

Key operative steps: Laminectomy and partial bony removal (including <¼ pedicle), creation of a cavity by removing small cranial/caudal endplate portions, then using an ultrasound-visualized curette to push the disk fragment ventrally into the cavity for safe removal, with repeat IOUS confirmation of anterior cord decompression.

Clinical outcomes: Significant improvement in pain and neurological/ambulatory function (VAS 5.9±2.0 to 1.8±1.2; Nurick 2.8±0.7 to 1.0±0.8; P<.001 for both).

Perioperative metrics: Mean operative time 132.8±32.9 minutes, mean blood loss 118.1±77.6 mL, and average length of stay 4.7±2.6 days.

Safety/fusion: No postoperative complications were observed; among those with ≥1-year follow-up (30/32), all achieved Lenke-Bridwell Grade A or B fusion without pseudarthrosis or revision surgery.

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Multi-Institutional Assessment of Circulating Cell-Free DNA in Cerebrospinal Fluid Facilitates Central Nervous System Lymphoma Diagnosis and Treatment Initiation

Neurosurgery 99:40–49, 2026

This multi-institutional clinical study evaluates a CLIA-certified rapid PCR assay detecting the MYD88 L265P variant in cell-free DNA from cerebrospinal fluid to diagnose central nervous system (CNS) lymphoma. The assay demonstrated 100% specificity, 40% sensitivity, and facilitated earlier treatment initiation, sometimes obviating the need for risky CNS tissue biopsy.

The report details prospective implementation across 19 hospitals, methods for CSF processing and qPCR, diagnostic performance metrics, clinical trajectories of MYD88-positive patients, and implications for using CSF liquid biopsy to accelerate safe, targeted CNS lymphoma therapy.

Clinical need CNS lymphoma diagnosis has historically relied on CNS tissue biopsy, which can delay treatment and carries neurological morbidity risk.

Assay approach A CLIA-certified rapid PCR test was implemented to detect the MYD88 L265P variant in cell-free DNA (cfDNA) from CSF as a minimally invasive diagnostic method.

Deployment scale Prospective testing was conducted over 16 months across 19 hospitals: 201 samples from 184 patients; 19 samples (18 patients) were MYD88 L265P positive, with 2 test failures from inadequate DNA.

Performance characteristics In patients with available records, the assay showed specificity 100%, sensitivity 40%, PPV 100%, NPV 83% (positive LR ∞; negative LR 0.6).

Clinical utility Positive MYD88 results enabled CNS lymphoma–directed treatment initiation, including cases treated without CNS tissue confirmation, with 100% concordance between CSF and CNS tissue biopsy among contemporaneous paired cases (N=8).

Time impact MYD88-positive results often returned before biopsy (median 5.5 vs 10.5 days from admission), and time to treatment was shorter when LP/CSF testing avoided CNS biopsy (7 vs 9 days, P=.048).

Predictors/limitations Detection was more likely with leptomeningeal disease (multivariable P=.017) and DLBCL histology (multivariable P=.027); sensitivity remained modest, implying negative tests still require further workup such as biopsy.

Practice caveat (annotation) Because of modest sensitivity and concerns about spectrum bias/loss to follow-up, MYD88 CSF testing can supplement or obviate biopsy in selected cases, but generally does not replace the need for tissue-based molecular profiling.

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