Levels of autonomy in FDA-cleared surgical robots: a systematic review.

The integration of robotics in surgery has increased over the past decade, and advances in the autonomous capabilities of surgical robots have paralleled that of assistive and industrial robots. However, classification and regulatory frameworks have not kept pace with the increasing autonomy of surgical robots. There is a need to modernize our classification to understand technological trends and prepare to regulate and streamline surgical practice around these robotic systems. We present a systematic review of all surgical robots cleared by the United States Food and Drug Administration (FDA) from 2015 to 2023, utilizing a classification system that we call Levels of Autonomy in Surgical Robotics (LASR) to categorize each robot's decision-making and action-taking abilities from Level 1 (Robot Assistance) to Level 5 (Full Autonomy). We searched the 510(k), De Novo, and AccessGUDID databases in December 2023 and included all medical devices fitting our definition of a surgical robot. 37,981 records were screened to identify 49 surgical robots. Most surgical robots were at Level 1 (86%) and some reached Level 3 (Conditional Autonomy) (6%). 2 surgical robots were recognized by the FDA to have machine learning-enabled capabilities, while more were reported to have these capabilities in their marketing materials. Most surgical robots were introduced via the 510(k) pathway, but a growing number via the De Novo pathway. This review highlights trends toward greater autonomy in surgical robotics. Implementing regulatory frameworks that acknowledge varying levels of autonomy in surgical robots may help ensure their safe and effective integration into surgical practice.

Bone Cements Used in Vertebral Augmentation: A State-of-the-art Narrative Review.

Vertebral compression fractures (VCFs) are common in osteoporotic patients, with a frequency projected to increase alongside a growing geriatric population. VCFs often result in debilitating back pain and decreased mobility. Cement augmentation, a minimally invasive surgical technique, is widely used to stabilize fractures and restore vertebral height. Acrylic-based cements and calcium phosphate cements are currently the two primary fill materials utilized for these procedures. Despite their effectiveness, acrylic bone cements and calcium phosphate cements have been associated with various intraoperative and postoperative incidents impacting VCF treatment. Over the past decade, discoveries in the field of biomedical engineering and material science have shown advancements toward addressing these limitations. This narrative review aims to assess the potential pitfalls and barriers of the various types of bone cements.

Identifying Predictors of Initial Surgical Failure during Minimally Invasive Endoscopic Intracerebral Hemorrhage Evacuation.

Background and Purpose: Intracerebral hemorrhage (ICH) is a common and severe disease with high rates of morbidity and mortality; however, minimally invasive surgical (MIS) hematoma evacuation represents a promising avenue for treatment. In February of 2019, the MISTIE III study found that stereotactic thrombolysis with catheter drainage did not benefit patients with supratentorial spontaneous ICH but that a clinical benefit may be present when no more than 15 mL of hematoma remains at the end of treatment. Intraoperative CT (iCT) imaging has the ability to assess whether or not this surgical goal has been met in real time, allowing for operations to add additional CT-informed 'evacuation periods' (EPs) to achieve the surgical goal. Here, we report on the frequency and predictors of initial surgical failure on at least one iCT requiring additional EPs in a large cohort of patients undergoing endoscopic minimally invasive ICH evacuation with the SCUBA technique. Methods: All patients who underwent minimally invasive endoscopic evacuation of supratentorial spontaneous ICH in a major health system between December 2015 and October 2018 were included in this study. Patient demographics, clinical and radiographic features, procedural details, and outcomes were analyzed retrospectively from a prospectively collected database. Procedures were characterized as initially successful when the first iCT demonstrated that surgical success had been achieved and initially unsuccessful when the surgical goal was not achieved, and additional EPs were performed. The surgical goal was prospectively identified in December of 2015 as leaving no more than 20% of the preoperative hematoma volume at the end of the procedure. Descriptive statistics and regression analyses were performed to identify predictors of initial failure and secondary rescue. Results: Patients (100) underwent minimally invasive endoscopic ICH evacuation in the angiography suite during the study time period. In 14 cases, the surgical goal was not met on the first iCT and multiple Eps were performed; in 10 cases the surgical goal was not met, and no additional EPs were performed. In 14 cases, the surgical goal was never achieved. When additional EPs were performed, a rescue rate of 71.4% (10/14) was seen, bringing the total percentage of cases meeting the surgical goal to 86% across the entire cohort. Cases in which the surgical goal was not achieved were significantly associated with older patients (68 years vs. 60 years; p = 0.0197) and higher rates of intraventricular hemorrhage (34.2% vs. 70.8%; p = 0.0021). Cases in which the surgical goal was rescued from initial failure had similar levels of IVH, suggesting that these additional complexities can be overcome with the use of additional iCT-informed EPs. Conclusions: Initial and ultimate surgical failure occurs in a small percentage of patients undergoing minimally invasive endoscopic ICH evacuation. The use of intraoperative imaging provides an opportunity to evaluate whether or not the surgical goal has been achieved, and to continue the procedure if the surgeon feels that more evacuation is achievable. Now that level-one evidence exists to target a surgical evacuation goal during minimally invasive ICH evacuation, intraoperative imaging, such as iCT, plays an important role in aiding the surgical team to achieve the surgical goal.

A Novel Port to Facilitate Magnetic Hyperthermia Therapy for Glioma.

High-grade gliomas (HGG) are the most common primary brain malignancy and continue to be associated with a dismal prognosis (median survival rate of 15-18 months) with standard of care therapy. Magnetic hyperthermia therapy (MHT) is an emerging intervention that leverages the ferromagnetic properties of magnetic iron-oxide nanoparticles (MIONPs) to target cancer cells that are otherwise left behind after resection. We report a novel port device to facilitate localization, delivery, and temperature measurement of MIONPs within a target lesion for MHT therapy. We conducted an in-depth literature and intellectual property review to define specifications of the conceived port device. After setting the design parameters, a thorough collaboration with neurological surgeons guided the iterative modeling process. A prototype was developed using Fusion 360 (Autodesk, San Rafael, CA) and printed on a Form 3 printer (Formlabs, Medford, MA) in Durable resin. The prototype was then tested in a phantom skull printed on a Pro-Jet 660Pro 3D printer (3D Systems, Rock Hill, SC) and a brain model based on mechanical and electrochemical properties of native brain tissue. This phantom underwent MHT heating tests using an alternating magnetic field (AMF) sequence based on current MHT workflow. Successful localization, delivery, and temperature measurement were demonstrated. The purpose of this study was twofold: first, to create and validate the procedural framework for a novel device, providing the groundwork for an upcoming comprehensive animal trial and second, to elucidate a cooperative approach between engineers and clinicians that propels advancements in medical innovation.

Surgical techniques for evacuation of chronic subdural hematoma: a mini-review.

Chronic subdural hematoma is one of the most common neurosurgical pathologies with over 160,000 cases in the United States and Europe each year. The current standard of care involves surgically evacuating the hematoma through a cranial opening, however, varied patient risk profiles, a significant recurrence rate, and increasing financial burden have sparked innovation in the field. This mini-review provides a brief overview of currently used evacuation techniques, including emerging adjuncts such as endoscopic assistance and middle meningeal artery embolization. This review synthesizes the body of available evidence on efficacy and risk profiles for each critical aspect of surgical technique in cSDH evacuation and provides insight into trends in the field and promising new technologies.

Endoscopic odontoidectomy for brainstem compression in association with posterior fossa decompression and occipitocervical fusion.

OBJECTIVE: Endonasal endoscopic odontoidectomy (EEO) is an alternative to transoral surgery for symptomatic ventral compression of the anterior cervicomedullary junction (CMJ), allowing for earlier extubation and feeding. Because the procedure destabilizes the C1-2 ligamentous complex, posterior cervical fusion is often performed concomitantly. The authors' institutional experience was reviewed to describe the indications, outcomes, and complications in a large series of EEO surgical procedures in which EEO was combined with posterior decompression and fusion. METHODS: A consecutive, prospective series of patients who underwent EEO between 2011 and 2021 was studied. Demographic and outcome metrics, radiographic parameters, extent of ventral compression, extent of dens removal, and increase in CSF space ventral to the brainstem were measured on the preoperative and postoperative scans (first and most recent scans). RESULTS: Forty-two patients (26.2% pediatric) underwent EEO: 78.6% had basilar invagination, and 76.2% had Chiari type I malformation. The mean ± SD age was 33.6 ± 3.0 years, with a mean follow-up of 32.3 ± 4.0 months. The majority of patients (95.2%) underwent posterior decompression and fusion immediately before EEO. Two patients underwent prior fusion. There were 7 intraoperative CSF leaks but no postoperative CSF leaks. The inferior limit of decompression fell between the nasoaxial and rhinopalatine lines. The mean ± SD vertical height of dens resection was 11.98 ± 0.45 mm, equivalent to a mean ± SD resection of 74.18% ± 2.56%. The mean increase in ventral CSF space immediately postoperatively was 1.68 ± 0.17 mm (p < 0.0001), which increased to 2.75 ± 0.23 mm (p < 0.0001) at the most recent follow-up (p < 0.0001). The median (range) length of stay was 5 (2-33) days. The median time to extubation was 0 (0-3) days. The median time to oral feeding (defined as, at minimum, toleration of a clear liquid diet) was 1 (0-3) day. Symptoms improved in 97.6% of patients. Complications were rare and mostly associated with the cervical fusion portion of the combined surgical procedures. CONCLUSIONS: EEO is safe and effective for achieving anterior CMJ decompression and is often accompanied by posterior cervical stabilization. Ventral decompression improves over time. EEO should be considered for patients with appropriate indications.

Combined transarterial and percutaneous preoperative embolization of transosseous meningioma.

Meningiomas with transosseous extension provide opportunities for extensive preoperative embolization, through conventional trans-arterial approaches, and also through less commonly used percutaneous methods. This video demonstrates embolization of a 7.6 × 9.5 × 9.9 cm transosseous WHO grade II meningioma.1 Trans-arterial embolization was conducted via the left middle meningeal, occipital, and superficial temporal arteries. Only one superficial temporal artery was embolized to preserve vascular supply to the skin flap. To further devascularize the tumor, concomitant percutaneous embolization was performed. Transosseous extension of the tumor facilitated extensive percutaneous embolization of both the intracranial and extracranial components of the mass. Intraoperative bleeding from the scalp and extracranial component of the tumor was minimal. The intracranial tumor was soft and necrotic and was removed with suction and gentle dissection. Residual tumor was left behind within and adjacent to the superior sagittal sinus. The patient recovered without neurological deficit and was referred for radiation of the residual tumor.

Middle Meningeal Artery Embolization for Chronic Subdural Hematoma Using N-Butyl Cyanoacrylate With D5W Push Technique.

BACKGROUND: Middle meningeal artery (MMA) embolization has been recognized as a promising treatment for patients with subdural hematoma (SDH). OBJECTIVE: To present the technical feasibility and efficacy of n-butyl cyanoacrylate (n-BCA) embolization in the largest consecutive cohort to date. METHODS: We retrospectively reviewed our consecutive cases of recurrent SDH treated with MMA embolization using diluted n-BCA with the "sugar rush" technique. In brief, a 2.1-Fr microcatheter was used to selectively catheterize the frontal and posterior branches of the MMA. 5% dextrose in water (D5W) was injected through an intermediate catheter while injecting n-BCA through the microcatheter. Complete obliteration of MMA and lack of SDH recurrence in a 3-6 months follow-up computed tomography scan were defined as efficacy outcomes. Cranial nerve palsy, vision loss, transient neurological deficit, and stroke were defined as safety outcomes. RESULTS: A total of 61 patients were identified with a mean (±standard deviation) age of 62.5 ± 9 years. In 6 patients (10%), coil embolization of the origin of the frontal or posterior branch was performed because super-selective catheterization of the branch was unsuccessful because of tortuous anatomy. Complete obliteration of frontal and posterior branches was achieved in 100% of the cases. Recurrent SDH was seen in 3 patients (5%). No incidence of cranial nerve palsy, vision loss, or stroke occurred. One patient suffered a transient neurological deficit. CONCLUSION: MMA embolization using diluted n-BCA with concomitant D5W injection is associated with a high degree of distal penetration and complete branch occlusion and minimal risk of cranial nerve palsy or other thromboembolic complications.

Endoscopic Third Ventriculostomy With "Rescue" Fourth Ventriculocisternostomy: 2-Dimensional Operative Video.

This case of endoscopic third ventriculostomy (ETV) and flexible endoscopy for lysis of fourth ventricle adhesions for obstructive hydrocephalus illustrates a key anatomical variant (anastomosis of posterior communicating arteries) that increases the difficulty of ETV and should be recognized preoperatively. The video further demonstrates flexible endoscopy for lysis of a fourth ventricular web and excellent third and fourth ventricular anatomy. This patient presented with normal pressure hydrocephalus-like symptoms and magnetic resonance imaging suggestive of a fourth ventricular outflow obstruction. An ETV would be an ideal intervention with a high chance of success1 and avoiding a ventriculoperitoneal shunt or a more invasive suboccipital craniectomy for fourth ventricle exploration; however, variant anatomy and resultant medialization of the bilateral posterior communicating arteries put their location directly beneath the tuber cinereum. After discussing the risks and benefits of the proposed procedure, the patient consented to proceeding with the surgery. Patient is not identifiable either by clinical vignette or through this operative video, which is entirely intraventricular. The care rendered was standard (nonexperimental). The patient did sign consent for filming and production of the educational video submitted. Here, we present operative video from our ETV, demonstrating an inability to confirm adequate fenestration and subsequent flexible endoscopy for fourth ventriculocisternostomy.

Robotic Resection of a Nerve Sheath Tumor Via a Retroperitoneal Approach.

BACKGROUND: Resection of large nerve sheath tumors in the lumbar spine using minimally invasive approaches is challenging, as approaches to tumors in this region may require facetectomy or partial resection of adjacent ribs for access to the involved neuroforamen and instrumentation across the involved joint to prevent subsequent kyphotic deformity. OBJECTIVE: To describe a robot-assisted retroperitoneal approach for resection of a lumbar nerve sheath tumor, obviating the need for facetectomy and instrumentation. The operation is described, together with intraoperative images and an annotated video, in the context of a schwannoma arising from the right L1 root. METHODS: The operation was performed by a urologic surgeon and a neurosurgeon. The patient was placed in lateral position, and the da Vinci Xi robot was used for retroperitoneal access via 5 ports along the right flank. Ultrasound was used to localize the tumor within the psoas. The tumor capsule was defined and released. Encountered nerves were stimulated, allowing small sensory nerves to be identified and safely divided. The tumor was traced into the right L1-L2 neuroforamen and removed. RESULTS: Complete en bloc resection of the tumor was achieved, including the paraspinal and foraminal components, without any removal of bone and without violation of the dura. CONCLUSION: In selected patients, a robot-assisted retroperitoneal approach represents a minimally invasive alternative to traditional approaches for resection of lumbar nerve sheath tumors. This approach obviates the need for bone removal and instrumented spinal fusion. Interdisciplinary collaboration, as well as use of adjunctive technologies, including intraoperative ultrasound and neurophysiologic monitoring, is advised.

Limited utility of 5-ALA optical fluorescence in endoscopic endonasal skull base surgery: a multicenter retrospective study.

OBJECTIVE: Incomplete resection of skull base pathology may result in local tumor recurrence. This study investigates the utility of 5-aminolevulinic acid (5-ALA) fluorescence during endoscopic endonasal approaches (EEAs) to increase visibility of pathologic tissue. METHODS: This retrospective multicenter series comprises patients with planned resection of an anterior skull base lesion who received preoperative 5-ALA at two tertiary care centers. Diagnostic use of a blue light endoscope was performed during EEA for all cases. Demographic and tumor characteristics as well as fluorescence status, quality, and homogeneity were assessed for each skull base pathology. RESULTS: Twenty-eight skull base pathologies underwent blue-light EEA with preoperative 5-ALA, including 15 pituitary adenomas (54%), 4 meningiomas (14%), 3 craniopharyngiomas (11%), 2 Rathke's cleft cysts (7%), as well as plasmacytoma, esthesioneuroblastoma, and sinonasal squamous cell carcinoma. Of these, 6 (21%) of 28 showed invasive growth into surrounding structures such as dura, bone, or compartments of the cavernous sinus. Tumor fluorescence was detected in 2 cases (7%), with strong fluorescence in 1 tuberculum sellae meningioma and vague fluorescence in 1 pituicytoma. In all other cases fluorescence was absent. Faint fluorescence of the normal pituitary gland was seen in 1 (7%) of 15 cases. A comparison between the particular tumor entities as well as a correlation between invasiveness, WHO grade, Ki-67, and positive fluorescence did not show any significant association. CONCLUSIONS: With the possible exception of meningiomas, 5-ALA fluorescence has limited utility in the majority of endonasal skull base surgeries, although other pathology may be worth investigating.

Magnetic resonance venography for 3-dimensional live guidance during venous sinus stenting.

PURPOSE: The purpose of this study was to report the technique for intraprocedural guidance of endovascular Venous Sinus Stenting procedures using 3-Dimensional (3D) Magnetic Resonance Venography (MRV) as an overlay on live biplanar fluoroscopy. MATERIALS AND METHODS: Venous sinus stenting procedures performed between April and December, 2017 with 3D MRV fusion for live guidance were reviewed in this study. A thin-slice, contrast-enhanced MR Venogram was used to create 2 3D models - vessels and skull - for procedural guidance via augmented fluoroscopy (Vessel ASSIST, GE Healthcare, Chicago, IL). The skull model was used in the registration of the 3D overlay on both the frontal and lateral planes, which required 1-2 min of procedural time. The vessel model was used to mark landmarks such as the cortical vein ostia and stenosis on the 3D overlay fused with biplanar fluoroscopy. The retrospective imaging review was conducted by 3 neurointerventionalists and relied on a consensus confidence ranking on a 3-point Likert scale from 1- low confidence to 3- high confidence. The neurointerventionalists first reviewed the conventional 2-dimensional pre-stent deployment fluoroscopy images and then reviewed the corresponding images with the 3D MRV overlay. They ranked their confidence in their understanding of cortical venous anatomy for each group. Statistical analysis was performed using a Paired T Test at a 99% confidence interval. RESULTS: Ten cases were included in the retrospective image review. Operator confidence regarding the location of cortical veins was significantly increased using 3D MRV fusion during venous sinus stenting procedures (1.9 vs 2.9, p = .001). CONCLUSION: 3-Dimensional MRV fusion is feasible and helpful in understanding the venous sinus anatomy and location of important cortical veins during venous sinus stenting procedures.

Innovations in the Neurosurgical Management of Epilepsy.

Technical limitations and clinical challenges have historically limited the diagnostic tools and treatment methods available for surgical approaches to the management of epilepsy. By contrast, recent technological innovations in several areas hold significant promise in improving outcomes and decreasing morbidity. We review innovations in the neurosurgical management of epilepsy in several areas, including wireless recording and stimulation systems (particularly responsive neurostimulation [NeuroPace]), conformal electrodes for high-resolution electrocorticography, robot-assisted stereotactic surgery, optogenetics and optical imaging methods, novel positron emission tomography ligands, and new applications of focused ultrasonography. Investigation into genetic causes of and susceptibilities to epilepsy has introduced a new era of precision medicine, enabling the understanding of cell signaling mechanisms underlying epileptic activity as well as patient-specific molecularly targeted treatment options. We discuss the emerging path to individualized treatment plans, predicted outcomes, and improved selection of effective interventions, on the basis of these developments.

Transforaminal Endoscopic Lumbar Discectomy and Foraminotomy with Modified Radiofrequency Nerve Stimulator and Continuous Electromyography Under General Anesthesia.

BACKGROUND: Transforaminal endoscopic lumbar approaches involve working in Kambin's triangle. These procedures are performed on awake patients or under general anesthesia with continuous electromyography. Potential morbidity of this approach includes injury to exiting and traversing nerve roots, as substantial dissection or cauterization of overlying tissues is required for visualization. METHODS: We developed a novel connection system that accepts input from a bipolar radiofrequency probe to allow direct nerve stimulation in conjunction with electromyography. This study included 30 consecutive patients undergoing transforaminal endoscopic lumbar approaches for discectomies (73.3%), foraminal stenosis (23.3%), or lateral recess stenosis (3.3%). Demographic, operative, and outcomes data were collected. RESULTS: Average age of patients was 61.4 years, and the L4-5 segment was most commonly treated (65.6%). Electrophysiologic mapping of the exiting nerve root was attempted in 28 patients with an average stimulation threshold of 8.6 ± 0.9 mA. Mapping of the traversing nerve root was attempted in 12 patients with an average stimulation threshold of 6.0 ± 0.8 mA. There were no instances of new postoperative sensorimotor deficits or dysesthesia. These findings persisted through mean and median follow-up of 294 days and 165 days, respectively. No patient required subsequent lumbar surgery. CONCLUSIONS: Our modified instrumentation and technique allow for accurate identification of the exiting and traversing nerve roots with minimal changes to the workflow of transforaminal endoscopic lumbar approaches. Modification of a bipolar radiofrequency device connection arrangement is simple, inexpensive, and reusable. In this study, no patients developed injury or pain related to nerve root dysfunction.

Middle meningeal artery embolization for chronic subdural hematoma: Endovascular technique and radiographic findings.

Background and purpose Embolization of the middle meningeal artery (MMA) has recently been proposed as an alternative to surgery for treatment of chronic subdural hematoma (SDH), and several case reports have been published supporting its efficacy. It has been suggested that the primary pathologic process in chronic SDH is repeated microhemorrhaging into the subdural collection from fragile neovasculature within the SDH membrane that arises from distal branches of the MMA. Embolization could thus provide a means of eliminating this chronic rebleeding. Materials and methods Images were selected from MMA embolization procedures performed at our institution in order to illustrate the technique and theory behind its efficacy for treatment of chronic SDH. Results Images from MMA angiograms demonstrate the variability of MMA anatomy and help illustrate the importance of avoiding potential ophthalmic collaterals and branches supplying cranial nerves. The findings of irregular wispiness of the distal MMA vasculature, contrast outlining of the SDH membrane on angiography, and homogenous increased density within the SDH on postembolization head computed tomography are described. Conclusion MMA embolization may provide a safe alternative for treatment of chronic SDH, but careful angiographic assessment of MMA anatomy should be performed to avoid potential complications. The findings illustrated here lend support to the theory that the pathologic process of chronic SDH is repeated leakage of blood products from an inflamed, abnormal arterial neovasculature within the SDH membrane that arises from the MMA, and thus selective embolization could provide an effective treatment.

Middle Meningeal Artery Embolization as Treatment for Chronic Subdural Hematoma: A Case Series.

BACKGROUND: Traditional treatment for symptomatic subdural hematoma (SDH) has been surgical evacuation, but recurrence rates are high and patients often harbor complex medical comorbidities. Growth and recurrence is thought to be due to the highly friable nature of the vascularized membrane that forms after initial injury. There have been reported cases of middle meningeal artery (MMA) embolization for treatment of recurrent SDH after surgical evacuation with the goal of eliminating the arterial supply to this vascularized membrane. OBJECTIVE: To present the first known case series of MMA embolization as upfront treatment for symptomatic chronic SDHs that have failed conservative management in lieu of surgical evacuation. METHODS: Five patients with symptomatic chronic SDHs underwent MMA embolization using PVA microparticles at our institution. Size of SDH was recorded in maximum diameter and total volume. RESULTS: Four patients underwent unilateral and 1 underwent bilateral MMA embolization successfully. All cases had significant reduction in total volume of SDH at longest follow-up scan: 81.4 to 13.8 cc (7 wk), 48.5 to 8.7 cc (3 wk), 31.7 and 88 to 0 and 17 cc (14 wk, bilateral), 79.3 to 24.2 cc (8 wk), and 53.5 to 0 cc (6 wk). All patients had symptomatic relief with no complications. Histologic analysis of the chronic SDH membrane in a separate patient that required surgery revealed rich neovascularization with many capillaries and few small arterioles. CONCLUSION: MMA embolization could present a minimally invasive and low-risk initial treatment alternative to surgery for symptomatic chronic SDH when clinically appropriate.

Cranial neuropathy due to intradural disc herniation.

BACKGROUND AND IMPORTANCE: Herniated intervertebral disc fragments rarely penetrate the thecal sac, and intracranial hypotension attributable to such penetrating fragments is even more unusual. We describe the first reported case of a cranial neuropathy due to intradural herniation of a disc fragment, in which intracranial hypotension from a resulting cerebrospinal fluid leak caused bilateral abducens palsies. CLINICAL PRESENTATION: A 45-year-old man presented with a positional headache after having experienced a "popping" sensation in his back while lifting a heavy object. He also reported blurred vision and was noted to have lateral gaze palsies bilaterally. Magnetic resonance imaging (MRI) of the brain revealed bilateral subdural collections, abnormal pachymeningeal enhancement, and cerebellar tonsillar herniation, suggesting intracranial hypotension. T2-weighted MRI of the spine revealed extrusion of the T12-L1 disc and suggested the presence of a disc fragment in the intradural space, displacing the caudal nerve roots. A myelogram demonstrated a filling defect extending into the subarachnoid space adjacent to the disc herniation, consistent with a free disc fragment in the intradural space. A diagnosis of intracranial hypotension due to a cerebrospinal fluid leak resulting from an intradural herniated disc was made. The diagnosis was confirmed intraoperatively. CONCLUSION: Surgical removal of the herniated disc fragment and repair of the dural defect resulted in complete resolution of the cranial neuropathy. This rare etiology of a cranial neuropathy, arising from pathology in the thoracolumbar spine, illustrates the clinical teaching that the sixth cranial nerve is highly sensitive to deformation induced by intracranial hypotension.