Intraoperative Phase Contrast MRI Analysis of Cerebrospinal Fluid Velocities During Posterior Fossa Decompression for Chiari I Malformation.

BACKGROUND: Cerebrospinal fluid (CSF) velocity at the craniovertebral junction (CVJ) is known to be altered in patients with Chiari I malformation (CMI), and normalization of CSF velocities is associated with symptom resolution. However, preoperative and intraoperative prediction methods have thus far failed to identify patients in whom CSF velocities can be normalized with posterior fossa decompression (PFD) without duraplasty. Phase contrast MRI (PC-MRI) may assist not only in diagnosis of CMI but also in guiding the intraoperative decision to perform duraplasty during PFD. PURPOSE: To use intraoperative MRI data to quantify changes in CSF hydrodynamics at the CVJ during each step of PFD with duraplasty (PFDD) in 12 consecutive patients. STUDY TYPE: Retrospective case series with all patients imaged before, during and after decompression, and all data analyzed postprocedure. POPULATION/SUBJECTS: Pediatric patients, mean age 14 years (range 4-18), undergoing PFD for CMI. FIELD STRENGTH/SEQUENCE: Intraoperative studies involved a dedicated 1.5T Siemens MRI imager. PC-MRI scans were in the axial plane at the CVJ. ASSESSMENT: Two observers assessed measurements. STATISTICAL TEST: The equality of matched pairs of observations was tested using the Wilcoxon matched-pairs signed-ranks test. RESULTS: Data analyses of the PC-MRI demonstrated a marked and immediate increase in CSF velocity at the posterior CVJ during PFDD. Mean cranially-directed velocities increased by a mean of 1.049cm/s (P = 0.028) from preincision to postoperative measurement. There was a mean 0.45 cm/s (P = 0.022) increase in mean cranial velocity from preincision to bone decompression scans, and a mean 0.48 cm/s (P = 0.018) increase in mean velocity from preincision to duraplasty. DATA CONCLUSION: In all subjects, significant increases in the mean and peak velocities of cranially- and caudally-directed velocities were observed from preincision to post-PFDD scans at the posterior CVJ. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2020;51:1463-1470.

Cerebrospinal fluid velocity amplitudes within the cerebral aqueduct in healthy children and patients with Chiari I malformation.

PURPOSE: To assess the effects of cerebrospinal fluid (CSF) bidirectional motion in Chiari malformation type I (CMI), we monitored CSF velocity amplitudes on phase contrast MRI (PC-MRI) in patients before and after surgery; and in healthy volunteers. MATERIALS AND METHODS: 10 pediatric volunteers and 10 CMI patients participated in this study. CMI patients underwent PC-MRI scans before and approximately 14 months following surgery. Two parameters-amplitude of mean velocity (AMV) and amplitude of peak velocity (APV) of CSF-were derived from the data. Measurements were made at the mid-portion of the cerebral aqueduct, and anterior and posterior compartments of the spinal canal at the craniovertebral junction (CVJ). RESULTS: AMV and APV within the cerebral aqueduct were greater in preoperative assessments of the CMI patients compared to normal volunteers. Statistical significance was noted when comparing aqueductal AMV between the preoperative values and normal controls (P = 0.03), and before and after surgery in the CMI patients (P = 0.02). Lower values of AMV (P = 0.02) were noted in the anterior CVJ compartment in the patients before and after surgery when compared to the normal volunteers. There were no significant correlations (P = 0.06) noted for the APV at the CVJ between the normal control and patients, before or after surgery. CONCLUSION: In pediatric CMI patients, AMV for CSF within the cerebral aqueduct and anterior CVJ subarachnoid space are significantly elevated preoperatively and normalize following surgery. Given the biphasic CSF motion, measuring amplitude accounts for cranial and caudal flow. It may offer an alternative parameter to assess postsurgical outcome. J. Magn. Reson. Imaging 2016;44:463-470.

Percutaneous Juxtapedicular Cement Salvage of Failed Spinal Instrumentation? Institutional Experience and Cadaveric Biomechanical Study.

BACKGROUND AND OBJECTIVES: Instrumented spinal fusion constructs sometimes fail because of fatigue loading, frequently necessitating open revision surgery. Favorable outcomes after percutaneous juxtapedicular cement salvage (perc-cement salvage) of failing instrumentation have been described; however, this approach is not widely known among spine surgeons , and its biomechanical properties have not been evaluated. We report our institutional experience with perc-cement salvage and investigate the relative biomechanical strength of this technique as compared with 3 other common open revision techniques. METHODS: A retrospective chart review of patients who underwent perc-cement salvage was conducted. Biomechanical characterization of revision techniques was performed in a cadaveric model of critical pedicle screw failure. Three revision cohorts involved removal and replacement of hardware: (1) screw upsizing, (2) vertebroplasty, and (3) fenestrated screw with cement augmentation. These were compared with a cohort with perc-cement salvage performed using a juxtapedicular trajectory with the failed primary screw remaining engaged in the vertebral body. RESULTS: Ten patients underwent perc-cement salvage from 2018 to 2022 to address screw haloing and/or endplate fracture threatening construct integrity. Pain palliation was reported by 8/10 patients. Open revision surgery was required in 4/10 patients, an average of 8.9 months after the salvage procedure (range 6.2-14.7 months). Only one revision was due to progressive hardware dislodgement. The remainder avoided open revision surgery through an average of 1.9 years of follow-up. In the cadaveric study, there were no significant differences in pedicle screw pullout strength among any of the revision cohorts. CONCLUSION: Perc-cement salvage of failing instrumentation is reasonably efficacious. The technique is biomechanically noninferior to other revision strategies that require open surgery for removal and replacement of hardware. Open revision surgery may be avoided by perc-cement salvage in select cases.

Moyamoya syndrome associated with hemoglobin Southampton (Casper).

When moyamoya vasculopathy results from an associated disease, this vasculopathy is then referred to as moyamoya syndrome. Moyamoya syndrome has been reported in association with sickle cell disease, neurofibromatosis type 1, Down syndrome, radiation exposure, and other predisposing factors. Other than sickle cell disease, rare hemoglobinopathies, such as hemoglobin Fairfax and hemoglobin Alesha, have been reported to occur with moyamoya. We present a case of moyamoya syndrome associated with an unstable hemoglobinopathy, hemoglobin Southampton (Casper). This is the first reported case of moyamoya associated with this hemoglobinopathy.

Neuroanatomy of cranial dural vessels: implications for subdural hematoma embolization.

Adoption of middle meningeal artery embolization in the management of chronic subdural hematomas has led to a renewed interest in dural vascular anatomy. The readily identifiable major dural arteries and potential hazards associated with their embolization are well described. Less emphasized are several levels of intrinsic dural angioarchitecture, despite their more direct relationship to dural based diseases, such as subdural hematoma and dural fistula. Fortunately, microvascular aspects of dural anatomy, previously limited to ex vivo investigations, are becoming increasingly accessible to in vivo visualization, setting the stage for synthesis of the old and the new, and providing a rationale for the endovascular approach to subdural collections in particular. In contrast with traditional anatomical didactics, where descriptions advance from larger trunks to smaller pedicles, we present a strategic approach that proceeds from a fundamental understanding of the dural microvasculature and its relationship to larger vessels.

Transpalpebral Incision for Resection of an Ethmoidal Dural Arteriovenous Fistula: 2-Dimensional Operative Video.

Ethmoidal dural arteriovenous fistulas are vascular malformations with arterial supply from the anterior ethmoidal artery and ultimate drainage into the sagittal sinus.1-3 They are characterized by a high risk of hemorrhage. Microsurgical disconnection of the fistula represents a safe and robust treatment option. Endovascular treatment requires catheterization of the ophthalmic artery and carries a risk of visual deficits. The supraorbital craniotomy provides an excellent corridor to the anterior skull base and is well suited for the treatment of ethmoidal dural arteriovenous fistulas. The supraorbital craniotomy may be performed through a transpalpebral "eyelid" incision. The transpalpebral incision allows for a well-hidden scar and does not have any associated hair loss, as can be seen with the eyebrow incision. The patient consented to the procedure and being videotaped.

Stent-Assisted Coiling of a Sidewall Aneurysm of the Distal Middle Cerebral Artery: 2-Dimensional Operative Video.

Sidewall aneurysm treatment often requires complex management strategies. These can include advanced clipping techniques or stent-assisted coiling techniques. Endovascular coiling alone has been associated with high recurrence rates and is often not feasible.1-4 Flow-diversion embolization has recently become a standard of care for many aneurysms, demonstrating high occlusion rates.4,5 However, the third generation of coil-assist stents can be delivered with 0.0165" microcatheters, being an ideal adjunct to manage this group of aneurysms in more distal locations. In this video, a 16-yr-old teenager with Parry-Romberg syndrome and congenital adrenal hyperplasia had an incidental finding of a 6.5-mm sidewall aneurysm arising off the angular branch of the left middle cerebral artery, found during the work-up of complex partial seizures. The patient consented to the procedure. Due to his young age and aneurysm size, a decision was made to treat the aneurysm through an endovascular approach. Under general anesthesia, a transfemoral approach was carried out using a 6-French short sheath. A 6-French guiding catheter was left in the distal cervical left internal carotid artery; a 0.0165" microcatheter was used to first deploy a 3.0 × 15 mm Neuroform Atlas stent, completely covering the length of the aneurysm. Then, the stent was traversed with the microcatheter to coil the aneurysm. Follow-up cerebral angiogram confirmed complete occlusion of the aneurysm.

Intrareservoir Administration of Alteplase to Treat a Distal Ventriculoatrial Shunt Obstruction.

BACKGROUND: Ventriculoatrial shunts can be afflicted with distal malfunctions due to thrombus formation at the distal tip. Distal tip thrombus formation may occur more commonly in oncologic patients who are predisposed to hypercoagulability. CASE DESCRIPTION: A patient who had a ventriculoatrial shunt placed for leptomeningeal carcinomatosis presented with headaches and confusion and was found to have a partial distal shunt obstruction. Intrareservoir administration of alteplase resulted in resolution of her symptoms. Nuclear medicine shunt patency test demonstrated restoration of distal flow. CONCLUSIONS: Intrareservoir administration of alteplase can be a useful nonoperative treatment strategy for ventriculoatrial shunt malfunction. This strategy may be particularly useful in cases with higher perioperative risk, such as patients with advanced metastatic cancer.

Transnasal and Transoral Approaches to Atlantoaxial Synovial Cysts: Report of 3 Cases and Review of the Literature.

BACKGROUND: Synovial cysts are cystic masses lined with pseudostratified columnar cells and containing clear or xanthochromic fluid. Although they are commonly encountered in the lumbar spine, synovial cysts infrequently occur in the cervical spine and rarely involve the odontoid process. The causes of synovial cysts of the odontoid process are unknown, but growth of synovial rests, proliferation of multipotent mesenchymal cells, atlantoaxial instability, and trauma are thought to play a role. CASE DESCRIPTION: We present 3 cases of atlantoaxial cysts with the associated radiographic features, surgical management, and clinical outcomes. No patient had rheumatoid arthritis. In all cases, preoperative differential diagnosis included neoplastic pathologic changes. Two patients underwent odontoidectomy through either an endonasal or a transoral approach, followed by posterior occipitocervical fusion. The third patient underwent an endoscopic transsphenoidal approach for cyst decompression. CONCLUSIONS: Tissue diagnosis is important in confirming pathologic analysis because synovial cysts have radiographic characteristics similar to those of a wide variety of neoplasms of the craniovertebral junction.

Resolution of innumerable cerebral Nocardia paucivorans abscesses after medical management.

Nocardia species are an infrequent cause of brain abscesses. We report a 50-year-old man with Nocardia paucivorans cerebral abscesses. Brain MRI revealed innumerable small ring-enhancing lesions. The patient initially responded to treatment with antibiotics and steroids, but experienced worsening after discontinuation of steroids. Brain biopsy performed to exclude central nervous system lymphoma produced nodular tissue with branching filaments on silver stain. Steroids were re-initiated and tapered slowly. The patient completed 1year of antibiotic therapy, after which he had no neurological symptoms and complete resolution of all brain abscesses on MRI.

A Case of Complete Resolution of Hemiballismus After Carotid Endarterectomy.

BACKGROUND: Hemiballismus is a rare presentation of symptomatic carotid stenosis that is underreported in the neurosurgical literature. It is characterized by severe large-amplitude movements that are classically caused by lesions of the subthalamic nucleus. Given the arterial border zone position of the subthalamic nucleus between the anterior and posterior circulation, hemodynamically compromising carotid stenosis can lead to hypoperfusion in this location. CASE DESCRIPTION: We describe the case of a patient who presented with acute-onset hemiballismus that had complete resolution of symptoms after carotid endarterectomy. CONCLUSIONS: We suggest that neurovascular imaging should be part of the initial workup of this condition and that prompt diagnosis and treatment of carotid artery stenosis in patients who present with new-onset hemiballismus are essential for reducing risk of imminent stroke.