Post-operative tension spinal subdural extra-arachnoid hygroma of the lumbar spine: case series, literature review, and recommendations for clinical management.

OBJECTIVE: Case series presentation and literature review of patient group suffering from symptomatic tension subdural extra-arachnoid hygroma following decompressive surgery for degenerative lumbar stenosis or disc disease. The purpose was to better understand this rare post-operative complication with a pathognomic radiological sign to help recommend optimal strategies for clinical management. METHODS: Retrospective case series comprising seven cases from one tertiary Neurosurgical centre spanning a 10-year period from 2011 to 2021. Patients included were those known to have undergone a spinal procedure and subsequently to have developed a symptomatic spinal subdural extra-arachnoid hygroma (SSEH). A literature review was conducted using PubMed, MEDLINE and EMBASE (keywords 'subdural hygroma', 'lumbar CSF hygroma', 'extra arachnoid hygroma', 'extra-arachnoid CSF collection', 'CSF tension hygroma', 'lumbar extra arachnoid hygroma', 'lumbar spinal hygroma', 'post-operating spinal hygroma', 'post-operative spinal CSF collection') and through reading references cited in relevant articles. Articles involving post-operative SSEH following lumbar spinal surgery were included. RESULTS: Rare complication with only five other cases in the literature. Dural breach described intra-operatively in only 5 of 12 total cases from our series and the literature. 5 patients in our series were managed surgically with 2 being managed conservatively. All patients in our series improved symptomatically and radiologically following surgical or conservative management. CONCLUSIONS: This is a rare post-lumbar surgery complication that can cause rapidly deteriorating lower limb and sphincteric function. Surgical management with wide durotomy and arachnoid marsupialisation can lead to reversal of neurological deterioration and excellent clinical results. A delayed presentation with pseudomeningocele formation may be managed conservatively if neurology is stable or improving. It is a condition that it is important for the clinician to recognise in order to instigate appropriate management in a time-dependent fashion.

Slow-Growing Pituitary Metastasis from Renal Cell Carcinoma: Literature Review.

BACKGROUND: Tumor metastasis to the pituitary is rare, most commonly reported with either breast or lung cancer metastasizing to the neurohypophysis. Pituitary metastases of renal cell carcinoma (RCC) are by contrast infrequently described even within this scarce literature. We present an illustrative case of RCC pituitary metastasis 15 years after radical nephrectomy for primary disease and a review of the published literature. CASE DESCRIPTION: A 69-year-old female was diagnosed with a large sellar mass with suprasellar extension. The initial radiologic diagnosis was most in keeping with pituitary macroadenoma, although prominent vascular flow voids were noted. Endoscopic endonasal transsphenoidal adenectomy was challenging on account of significant intraoperative hemorrhage from an unusually vascular tumor. Pathologic examination supported a diagnosis of metastatic clear cell renal carcinoma. Literature review identified 41 cases of RCC pituitary metastasis since 1984. The mean age at time of diagnosis with pituitary metastasis was 59.5 years (range 35-81 years, 73% male). Pituitary metastasis was the initial presentation of RCC in 10 patients. The median time from RCC diagnosis to pituitary metastasis was 1 year (range 0-27 years). Surgical resection was performed for 30 patients, of which 47% reported a highly vascular tumor. CONCLUSIONS: We highlight the potential for delayed metastasis to the pituitary to masquerade as a macroadenoma. Imaging consistent with rich vascularity should bring the diagnosis of RCC metastasis into the differential and is important to note when planning surgical resection in such cases.

Giant Juvenile Ectopic Schwannoma of the Temporal Bone.

BACKGROUND: Ectopic intracranial schwannomas (those that do not arise from a named cranial nerve) are rare. They account for <2% of surgically resected central nervous system schwannomas. CASE DESCRIPTION: We report the case of a 14-year-old boy presenting with a left conductive hearing loss and temporal bone deformity. No facial or cranial nerve deficits were present. Cross-sectional imaging demonstrated a large expansile extra-axial temporal bone mass, extending into and distorting the middle cranial fossa. At surgical resection the tumor was functionally and anatomically distinct from the facial nerve or any other identifiable neural structure within the middle ear or temporal bone. Histology confirmed a World Health Organization grade 1 schwannoma. CONCLUSIONS: This is the first reported case of a giant juvenile ectopic schwannoma within the temporal bone.

Maximising coverage of brain structures using controlled reflux, convection-enhanced delivery and the recessed step catheter.

BACKGROUND: The design and use of convection-enhanced delivery catheters remains an active field as clinical trials have highlighted suboptimal distribution as a contributory factor to the failure of those studies. Recent studies indicate limitations and challenges in achieving target coverage using conventional point source delivery. NEW METHOD: The recessed step catheter(RSC), developed by this group, does not function as a point source delivery device, but instead uses 'controlled reflux' of the infusate to a flow inhibiting recess feature. Here we investigate a range of clinically useful step lengths in agarose gel and investigate proof-of-principle in vivo(n = 5). Infusion morphology was characterised in terms of length, width and distribution volume over a range of flow rates. RESULTS: For a fixed infusion volume, increases in catheter step length strongly correlated with increases in the length and volume of distribution (r>0.90, p < 0.001) whilst there were small reductions in the width of distribution (r<-0.62, p < 0.001). Step lengths below 6 mm produced spherical distributions while steps above 12 mm produced elongated distributions. Increasing peak flow rates resulted in significant reductions in distribution volume at each step length, and an increased risk of reflux beyond the step. Modifications to the infusion morphology using changes in step length were confirmed in vivo. CONCLUSIONS: The combination of the recessed step and the ability to adjust the step length with this catheter design make it highly suitable for tailoring the distribution volume of the infusate to meet specific morphological target volumes in the brain.

Therapeutic Targeting of Histone Modifications in Adult and Pediatric High-Grade Glioma.

Recent exciting work partly through The Cancer Genome Atlas has implicated epigenetic mechanisms including histone modifications in the development of both pediatric and adult high-grade glioma (HGG). Histone lysine methylation has emerged as an important player in regulating gene expression and chromatin function. Lysine (K) 27 (K27) is a critical residue in all seven histone 3 variants and the subject of posttranslational histone modifications, as it can be both methylated and acetylated. In pediatric HGG, two critical single-point mutations occur in the H3F3A gene encoding the regulatory histone variant H3.3. These mutations occur at lysine (K) 27 (K27M) and glycine (G) 34 (G34R/V), both of which are involved with key regulatory posttranscriptional modifications. Therefore, these mutations effect gene expression, cell differentiation, and telomere maintenance. In recent years, alterations in histone acetylation have provided novel opportunities to explore new pharmacological targeting, with histone deacetylase (HDAC) overexpression reported in high-grade, late-stage proliferative tumors. HDAC inhibitors have shown promising therapeutic potential in many malignancies. This review focuses on the epigenetic mechanisms propagating pediatric and adult HGGs, as well as summarizing the current advances in clinical trials using HDAC inhibitors.