Role of Magnetic Resonance Imaging in the Evaluation of Trigeminal Neuralgia Using Steady-State Imaging.

Trigeminal neuralgia (TN) poses diagnostic challenges due to its complex origins, often associated with neurovascular compression. Advanced imaging techniques, particularly magnetic resonance imaging (MRI) with the fast imaging employing steady-state acquisition (FIESTA) sequence, offer crucial insights into TN pathophysiology. This prospective cross-sectional observational study aimed to elucidate MRI's utility in diagnosing TN and correlating imaging findings with clinical manifestations and treatment outcomes. A cohort of 41 patients clinically suspected of TN underwent MRI evaluation at Acharya Vinoba Bhave Rural Hospital, Sawangi (Meghe), Wardha, utilizing various sequences including FIESTA. Analysis revealed a higher incidence among females, predominant unilateral presentation, and a higher prevalence of abnormal MRI findings, with neurovascular compression as the leading etiology. Correlation analysis demonstrated significant associations between facial pain localized to the trigeminal nerve distribution, triggering factors, and abnormal MRI findings. Gender distribution did not significantly influence MRI findings. Treatment outcomes favored microvascular surgery over conservative management in cases of neurovascular compression. This study underscores MRI's pivotal role, particularly FIESTA, in TN evaluation, guiding personalized treatment strategies and emphasizing the importance of integrated clinical and imaging approaches. Further research is warranted to validate these findings and explore additional imaging modalities for a deeper understanding of TN pathogenesis.

Intradural lumbar disc herniation with cauda equina syndrome: Case report and recent advances.

Introduction: Intradural lumbar disc herniations (IDDH) are unusual and represent less than 0.3% of all lumbar disc herniations. They have a higher incidence of cauda equina syndrome. The possibility of intradural disc herniation is often missed on Magnetic Resonance Imaging (MRI) and during surgery if the size of the disc prolapse is inconsistent with the compression seen on the MRI. In such situations, the possibility of IDDH should be suspected. Research question: How to diagnose intradural disc herniation pre-operatively? Surgical techniques if the intra-dural disc herniation is encountered intra-operatively. Material and methods: In this article, we describe a case report of an intradural disc herniation (IDDH) causing cauda equina syndrome at the L4-5 level and who underwent surgical decompression. This case report highlights that by doing a dorsal durotomy and by using microsurgical techniques, excision of the intradural disc fragment can be achieved without any rootlet injury. Results: At a 2-year follow-up, the patient has recovered completely from motor weakness and bowel and bladder incontinence. Discussion and conclusion: Though uncommon intra-dural disc herniation can be diagnosed pre-operatively by its characteristic signs or by using newer techniques like 3-dimensional constructive interference in steady state (CISS) MRI. Intra-operative ultrasonography (IOUS) is a handy tool to localise and diagnose intra-dural disc herniation intra-operatively and its use is encouraged. Timely intervention can lead to acceptable outcomes even with cauda equina syndrome.

Comprehensive evaluation of magnetic resonance imaging sequences for signal intensity based assessment of anterior cruciate ligament healing following surgical treatment.

Normalized signal intensity (SI) obtained from magnetic resonance imaging (MRI) has been used to track anterior cruciate ligament (ACL) postoperative remodeling. We aimed to assess the effect of MRI sequence (PD: proton density-weighted; T2: T2-weighted; CISS: constructive interference in steady state) on postoperative changes in healing ACLs/grafts. We hypothesized that CISS is better at detecting longitudinal SI and texture changes of the healing ACL/graft compared to the common clinical sequences (PD and T2). MR images of patients who underwent ACL surgery were evaluated and separated into groups based on surgical procedure (Bridge-Enhanced ACL Repair (BEAR; n = 50) versus ACL reconstruction (ACLR; n = 24)). CISS images showed decreasing SI across all timepoints in both the BEAR and ACLR groups (p < 0.01), PD and T2 images showed decreasing SI in the 6-to-12- and 12-to-24-month postoperative timeframes in the BEAR group (p < 0.02), and PD images additionally showed decreasing SI between 6- and 24-months postoperation in the ACLR group (p = 0.02). CISS images showed texture changes in both the BEAR and ACLR groups, showing increases in energy and decreases in entropy in the 6-to-12- and 6-to-24-month postoperative timeframes in the BEAR group (p < $\lt $ 0.04), and increases in energy, decreases in entropy, and increases in homogeneity between 6 and 24 months postoperation in the ACLR group (p < 0.04). PD images showed increases in energy and decreases in entropy between 6- and 24-months postoperation in the ACLR group (p < 0.008). Finally, CISS was estimated to require a smaller sample size than PD and T2 to detect SI differences related to postoperative remodeling.

Pituitary adenoma presenting as isolated oculomotor nerve palsy.

Background: Isolated oculomotor nerve palsy is a relatively uncommon symptom of pituitary adenoma that usually occurs in association with pituitary apoplexy or cavernous sinus (CS) invasion. Case Description: We report two cases of relatively small pituitary adenomas with neither apoplexy nor CS invasion presenting as isolated oculomotor nerve palsy. Both patients presented with gradually worsening diplopia, without headache or visual field defects. Magnetic resonance imaging (MRI) showed a pituitary tumor with no evidence of intratumoral hemorrhage. Computed tomography revealed a lateroposterior extension of the tumor with the erosion of the posterior clinoid process. Constructive interference in steady-state MRI revealed compression of the oculomotor nerve by the tumor at the oculomotor triangle. The patients underwent endoscopic transsphenoidal surgery, and the intraoperative findings showed that the tumors did not invade the CS. The tumors were completely resected, and the oculomotor palsies resolved fully. Conclusion: These cases illustrate the need to consider isolated oculomotor nerve palsy as an initial manifestation of a relatively small pituitary adenoma with neither apoplexy nor CS invasion. Based on the characteristic radiological findings, early surgical treatment is recommended to preserve oculomotor function.

A Rare Case of Idiopathic Spinal Cord Herniation Treated by DuraGen® Collagen Matrix Graft.

We report a rare case of idiopathic spinal cord herniation (ISCH) with a history of cerebrospinal fluid (CSF) leakage. ISCH is a protrusion of the spinal cord through a dural defect. Thin constructive interference in steady-state (CISS) images clearly demonstrated the herniated cord in the present case. The myelopathy worsened and the patient underwent surgery for reduction of herniated spinal cord; the dural defect was filled by placing collagen matrix graft (DuraGen®) between the inner and outer dural layers. The patient's symptoms have improved without relapse for 8 months since surgery. This method may be a good surgical option for cases of spinal cord herniation.

Three-Dimensional Constructive Interference in Steady State (3D CISS) Imaging and Clinical Applications in Brain Pathology.

Three-dimensional constructive interference in steady state (3D CISS) is a steady-state gradient-echo sequence in magnetic resonance imaging (MRI) that has been used in an increasing number of applications in the study of brain disease in recent years. Owing to the very high spatial resolution, the strong hyperintensity of the cerebrospinal fluid signal and the high contrast-to-noise ratio, 3D CISS can be employed in a wide range of scenarios, ranging from the traditional study of cranial nerves, the ventricular system, the subarachnoid cisterns and related pathology to more recently discussed applications, such as the fundamental role it can assume in the setting of acute ischemic stroke, vascular malformations, infections and several brain tumors. In this review, after briefly summarizing its fundamental physical principles, we examine in detail the various applications of 3D CISS in brain imaging, providing numerous representative cases, so as to help radiologists improve its use in imaging protocols in daily clinical practice.

Signal Alteration of the Inner Ear on High-Resolution Three-Dimensional Constructive Interference in Steady State Sequence in Patients with Ménière's Disease and Labyrinthitis.

INTRODUCTION: The aim of this study is to evaluate signal alteration in the inner ear using three-dimensional (3D)-constructive interference in steady state (CISS) sequence in patients with Ménière's disease and labyrinthitis and its correlation with clinical and audiological parameters. METHODS: The medical records of the department of otorhinolaryngology were searched for patients with Ménière's disease or labyrinthitis who underwent MRI with 3D-CISS sequence. Blinded analysis of these patients and of MRI from control subjects without middle or inner ear symptoms was performed to detect any signal asymmetry of the inner ear structures. The results were correlated with clinical symptoms and results of audiological and vestibular tests. RESULTS: Fifty-eight patients with definite Ménière's disease and 5 patients with labyrinthitis as well as 41 control exams were included. A separate analysis was performed for patients with probable Ménière's disease (n = 68). A total of 172 3D-CISS sequences were analyzed by 2 blinded independent neuroradiologists. A CISS-hypointense signal of the inner ear structures was found in 3 patients with definite Ménière's disease (5.2%), in 4 patients with probable Ménière's disease (5.9%), and 2 patients with labyrinthitis (40%). No CISS hypointensity was found in the control group. Although no significant difference in symptoms or audiological test results was found between patients with and without this signal change, the side of hypointensity was frequently correlated with the symptomatic side and with hearing impairment. DISCUSSION/CONCLUSION: CISS hypointensity of the inner ear structures was evident in patients with clinical conditions other than vestibular schwannoma - more frequently in labyrinthitis than in Ménière's disease. This signal alteration was frequently encountered on the same symptomatic side as that of the pathological audiology tests, but it is not a predictor for hearing or vestibular impairment.

Comparison of 3D constructive interference in steady state (CISS) and T2 sampling perfection with application optimized contrasts using different flip angle evolution MR imaging of the intracranial trigeminal nerve and central skull base neuroforamina.

BACKGROUND AND PURPOSE: Due to surgical advancements, the accurate detection of perineural disease spread has become increasingly important in the management and prognostication of head and neck cancers, though MR evaluation has thus far been limited by technical and logistic challenges. The purpose of this study was to specifically evaluate the relative capability of 3D CISS and 3D T2-SPACE imaging to delineate the proximal intracranial divisions of the normal trigeminal nerve, an area important in determining the resectability of intracranial perineural disease. MATERIALS AND METHODS: A single center HIPAA-compliant, IRB approved retrospective review of 40 patients with clinical temporal bone/internal auditory canal MR imaging was conducted. 20 patients with 3D CISS images and 20 patients with 3D T2-SPACE images met inclusion criteria. Two radiologists scored the sequences on a 3-point scale based on ability to visualize anatomic structures surrounding the trigeminal nerve in Meckel's cave, intracranial trigeminal divisions, skull base neuroforamina, and proximal extracranial mandibular division. RESULTS: The following anatomic locations scored significantly better in the T2-SPACE sequence compared to the CISS sequence for both raters: intracranial V3 (p < .05), foramen ovale (p < .05), and extracranial V3 (p < .01). The average scores for the anterior Meckel's cave and foramen rotundum were higher for the T2-SPACE sequence, although not significantly. Percent interobserver agreement ranged from 50 to 90% and 65-100% for the different anatomic locations on the CISS and T2-SPACE sequences, respectively. CONCLUSION: 3D T2-SPACE was found to be superior to 3D CISS in the evaluation of the distal intracranial and extracranial portions of the normal trigeminal nerve.

A Case of Trigeminal Neuralgia Due to Cerebellopontine Epidermoid Cyst: Discrepancy between Intraoperative and Radiological Findings of Constructive Interference in Steady State (CISS).

Trigeminal neuralgia (TN) is characterized by lightning pain paroxysms in the somatosensory distribution of the trigeminal nerve accompanied by hypersensitivity to non-nociceptive stimuli. Epidermoid cysts sometimes cause TN. To plan the surgery, constructive interference in steady state (CISS) image is useful for understanding the tumor's location, extent, and relationship against the cranial nerves, and epidermoid cysts are shown as hypointense compared to cerebrospinal fluid (CSF). However, we herein describe a case with TN due to epidermoid cysts, whose intraoperative findings are different from the preoperative and postoperative CISS image. A 49-year-old woman has suffered from TN. CISS images revealed the prolonged trigeminal nerve and the hypointense tumor compared to the CSF at the right cerebellopontine angle. CISS image suggested that the tumor would surround the trigeminal nerve, reach into the Meckel cavity, and offend and compress the trigeminal nerve's root entry zone (REZ). However, contrary to our expectation, the trigeminal nerve was not surrounded by the tumor. Neuroendoscope revealed that the tumor compressed the REZ, but the tumor was not present in the Meckel cavity. We performed partial tumor removal around the trigeminal nerve, and her symptoms improved. However, the postoperative CISS image was similar to the preoperative one, and so we could not evaluate the remaining tumor. The pathological diagnosis was epidermoid cysts. Intraoperative findings are sometimes different from the pre- and postoperative CISS images, making it difficult to follow up the remaining part of the epidermoid cyst.

[Improved Neural Imaging Sequence and Comparison with Conventional Methods].

The purpose of this study was to improve the contrast between the nerves and blood by reconsidering the imaging parameters of the sampling perfection with application-optimized contrasts using different flip angle evolutions (SPACE) method, and to compare it with conventional methods, including the constructive interference in steady state (CISS) and T2-weighted SPACE (T2-SPACE) methods. In the phantom study, the repetition time (TR), echo time (TE), flip angle (FA), and turbo factor (TF) of SPACE were varied using the restore pulse. The parameters for which the nerve-blood contrast (C1) and cerebrospinal fluid-nerve contrast (C2) were equal were selected. Though multiple conditions resulted in C1 and C2 equivalence, we determined/set the TR=500 ms, TE=21 ms,  FA=120°, and  TF=30, considering the acquisition time, specific absorption rate (SAR), and artifacts. This sequence was called "short TR and short TE SPACE with restore pulse (SSSR)". In the phantom and healthy volunteer studies, the contrast between the nerves and blood in the SSSR method was statistically superior in both the physical and visual assessments compared with conventional methods. In the healthy volunteer study, C1 improved from 0.08 for CISS and 0.18 for T2-SPACE to 0.43 for SSSR. This is because the nerve signals in conventional methods were low due to the heavy T2-weighted, while those in the SSSR method were high due to the short TE and effect of the restore pulse. In conclusion, the contrast between the nerves and blood was significantly higher in the SSSR method compared with conventional methods.

Cause of acquired onset of diplopia due to isolated third, fourth, and sixth cranial nerve palsies in patients aged 20 to 50 years in Korea: A high resolution magnetic resonance imaging study.

AIMS: This study aimed to describe the etiologies of acquired onset of diplopia due to isolated third, fourth, and sixth cranial nerve palsies in young adults in Korea. METHODS: This retrospective study included 127 patients aged 20 to 50 years with acquired onset isolated third, fourth, and sixth cranial nerve palsies who received care at the Strabismus and Neuro-ophthalmology Department of Samsung Medical Center from 2013 to 2017. The etiologies of the palsies determined by clinical assessment, high-resolution magnetic resonance imaging (MRI) with three-dimensional constructive interference in steady state, and laboratory testing were analyzed. RESULTS: Fifty-nine patients manifested sixth cranial nerve palsy. Forty-six patients had fourth cranial nerve palsy and 22 patients had third cranial nerve palsy. The most common etiologies of the ocular motor nerve palsies were presumed inflammatory lesions (21.3%), followed by presumed microvascular causes (17.3%), and neoplasms involving the central nervous system (15.7%). Neoplasms were the most common cause of sixth cranial nerve palsy (25.4%). The most common cause of fourth cranial nerve palsy was presumed microvascular ischemia (28.3%), and presumed inflammatory lesions was the most common cause of third cranial nerve palsy (36.4%). Other non-traumatic causes included vascular lesions, ischemic brainstem stroke, intracranial hemorrhage, non-aneurysmal neuro-vascular contact, multiple sclerosis, and infection. CONCLUSION: A substantial proportion of young adult patients with ocular motor nerve palsies manifested pathologies other than presumed microvascular ischemia or idiopathic causes. Neuroimaging and laboratory tests have important roles in the evaluation of patients aged 20-50 years with acquired ocular motor nerve palsies.

Practical applications of CISS MRI in spine imaging.

Routine magnetic resonance imaging evaluation of the spine is often limited by low spatial resolution and artifacts resulting from cerebrospinal fluid pulsation. Balanced steady-state free precession sequences can supplement routine spin echo sequences and provide exquisite anatomic detail and high cerebrospinal fluid-to-soft tissue contrast, adding significant diagnostic value to the evaluation of a wide variety of spine disorders.

Morphometric analysis of facial and cochlear nerves in normal-hearing ears using 3D-CISS.

PURPOSE: The aim of the current study was to establish a normative data set for the morphometric parameters of the facial nevre (FN) and cochlear nevre (CN) according to age and sex in the adult population, using 3-dimensional constructive interference in steady state (3D-CISS) sequence on magnetic resonance imaging. METHODS: We retrospectively analyzed 157 ears of 102 adults with no hearing impairment, facial palsy or Ménière's disease. The vertical (VD) and horizontal (HD) diameters as well as cross-sectional areas (CSAs) of the FNs and CNs were measured on the parasagittal oblique image created using the axial 3D-CISS sections passing through the internal acoustic canal. We related the measurement results with side, sex and age. RESULTS: The mean VD, HD and CSA of the FNs were 1.09 ±â€¯0.18 mm, 0.84 ±â€¯0.17 mm, and 0.75 ±â€¯0.27 mm2, respectively, whereas those of the CNs were 1.34 ±â€¯0.17 mm, 1 ±â€¯0.15 mm and 1.06 ±â€¯0.3 mm2, respectively. There was no statistically significant difference between the morphometric parameters of both the nerves according to side or sex (P > 0.05). However, except for the CSA of the FNs among males, we found a statistically significant decrease in all the morphometric parameters of both the nerves with ageing (P < 0.05). CONCLUSION: The normative morphometric data obtained in this study can be beneficial in clinical applications for sensorineural hearing loss, facial palsy and Ménière's disease.

Superficial siderosis associated with duplicated dura mater detected by CISS reverse MRI.

Superficial siderosis (SS) of the central nervous system is a rare disease caused by chronic or repeated hemorrhages in the subarachnoid space. Closure of dural defects is an effective therapy for SS. Conventional magnetic resonance imaging (MRI), however, cannot sufficiently detect dural tears. To better detect these defects, we analyzed the clinical data of consecutive patients admitted to our department with SS and performed constructive interference in steady-state (CISS) reverse MRI of the brain and spinal cord. CISS reverse method emphasizes the contrast between the dura and cerebrospinal fluid, enabling detection of dural defects better than usual T2-weighted MRI. CISS reverse MRI detected fluid-filled collections in five of the seven SS patients we studied. These images showed that the fluid-filled collections were packed within duplicated dura mater. In three of the five, dural defects were confirmed intraoperatively. We postulate that fluid-filled collections are actually derived from dissection of the dura mater. In accordance with the Monro-Kellie hypothesis, we propose that CSF transferal into the fluid-filled collections via dural defects induces an increase in blood volume and promotes the exudation of blood from engorged vessels. In patients with SS, it is very important to repair dural defects to prevent further associated neurological impairment. CISS reverse MRI is useful for detecting such dural defects.

Superiority of constructive interference in steady-state MRI sequencing over T1-weighted MRI sequencing for evaluating cavernous sinus invasion by pituitary macroadenomas.

OBJECTIVEPreoperatively determining the extent of parasellar invasion of pituitary macroadenomas is useful for surgical planning and patient counseling. Here, the authors compared constructive interference in steady state (CISS), a T2-weighted gradient-echo MRI sequence, to volume-interpolated breath-hold examination (VIBE), a T1-weighted gradient-echo MRI sequence, for evaluation of cavernous sinus invasion (CSI) by pituitary macroadenomas.METHODSVIBE and CISS images of 98 patients with pituitary macroadenoma were retrospectively analyzed and graded using the modified Knosp classification. The Knosp grades were correlated to surgical findings of CSI, which were determined intraoperatively using 0° and 30° endoscopes. The predictive accuracies for CSI according to the Knosp grades derived from the CISS and VIBE images were compared using receiver operating characteristic (ROC) curves. Postoperative MRI was used to evaluate the gross-total resection (GTR) rates.RESULTSThe CSI rate by pituitary macroadenomas was 27.6% (27 of 98 cases). Of 196 assessments (left and right sides of 98 macroadenomas), 45 (23.0%) had different Knosp grades when scored using VIBE versus CISS images. For the VIBE images, 0% of Knosp grade 0, 4.5% of grade 1, 23.8% of grade 2, 42.1% of grade 3A, 100% of grade 3B, and 83.3% of grade 4 macroadenomas were found to have CSI intraoperatively. For the CISS images, 0% of Knosp grade 0, 2.1% of grade 1, 31.3% of grade 2, 56.3% of grade 3A, 100% of grade 3B, and 100% of grade 4 macroadenomas were found to have CSI intraoperatively. Two pituitary macroadenomas were classified as grade 4 on VIBE sequences but grades 3A and 2 on CISS sequences; CSI was not observed intraoperatively in both cases. The GTR rate was 64.3% and 60.0% for high-grade (3A, 3B, and 4) macroadenomas classified using VIBE and CISS sequences, respectively. The areas under the ROC curves were 0.94 and 0.97 for VIBE- and CISS-derived Knosp grades (p = 0.007), respectively.CONCLUSIONSKnosp grades determined using CISS sequence images are better correlated with intraoperative CSI than those determined using VIBE sequence images. CISS sequences may be valuable for the preoperative assessment of pituitary macroadenomas.

Delayed facial palsy after microvascular decompression for hemifacial spasm: friend or foe?

OBJECTIVE The authors investigated the incidence, clinical course, and predisposing factors associated with delayed facial palsy (DFP) following microvascular decompression (MVD). METHODS The authors reviewed the records of 310 patients (311 cases) who were followed after MVD for hemifacial spasm (HFS). Of these patients, 45 (14.5%) developed DFP after MVD. The clinical characteristics and predisposing factors of the patients with HFS were investigated to identify prognostic factors that predicted the development of DFP after MVD. Log-rank tests were used to compare times to symptom disappearance, and a logistic regression analysis was performed to compare clinical characteristics between patients who developed DFP and those who did not. RESULTS HFS was completely resolved immediately after MVD in 158 cases (50.8%), and HFS eventually disappeared in 289 (92.9%) of the cases. Of the 45 patients with DFP, 17 were men and 28 were women. DFP occurred between postoperative Days 1 and 44 (mean 9.67 days). Finally, 44 patients (97.8%) completely recovered. The average time to recovery was 3.9 months (range 1-24 months). Patients who had experienced an immediate disappearance of HFS experienced a significantly higher occurrence of DFP than those who did not (odds ratio 0.383, 95% confidence interval 0.183-0.802; p = 0.011). In addition, preoperative botulinum neurotoxin injections negatively influenced the occurrence of DFP (p = 0.016). CONCLUSIONS In this study, the incidence rate of DFP was slightly higher than previously reported values. Moreover, DFP can occur even when spasms disappear immediately after MVD, but the patients with DFP can fully recover within weeks.

Spinal endoscopy combined with selective CT myelography for dural closure of the spinal dural defect with superficial siderosis: technical note.

The authors describe a new procedure to detect the tiny dural hole in patients with superficial siderosis (SS) and CSF leakage using a coronary angioscope system for spinal endoscopy and selective CT myelography using a spinal drainage tube. Under fluoroscopy, surgeons inserted the coronary angioscope into the spinal subarachnoid space, similar to the procedure of spinal drainage, and slowly advanced it to the cervical spine. The angioscope clearly showed the small dural hole and injured arachnoid membrane. One week later, the spinal drainage tube was inserted, and the tip of the drainage tube was located just below the level of the dural defect found by the spinal endoscopic examination. This selective CT myelography clarifies the location of the dural defect. During surgery, the small dural hole could be easily located, and it was securely sutured. It is sometimes difficult to detect the actual location of the small dural hole even with thin-slice MRI or dynamic CT myelography in patients with SS. The use of a coronary angioscope for the spinal endoscopy combined with selective CT myelography may provide an effective examination to assess dural closure of the spinal dural defect with SS in cases without obvious dural defects on conventional imaging.

Additive Value of 3T 3D CISS Imaging to Conventional MRI for Assessing the Abnormal Vessels of Spinal Dural Arteriovenous Fistulae.

INTRODUCTION: We investigated the additive value of the 3T 3D constructive interference in steady state (CISS) sequence to conventional MRI for the evaluation of spinal dural arteriovenous fistulae (SDAVF). MATERIALS AND METHODS: We included 16 consecutive patients (15 men, 1 woman; age range 42-81 years; mean 64 years) with SDAVF who underwent 3T MRI and digital subtraction angiography (DSA) before treatment. Two neuroradiologists independently evaluated the presence of abnormal vessels on 3D CISS-, T2- and T1-weighted images (T1WI, T2WI), and contrast-enhanced T1WI using a 3-point grading system. Interobserver agreement was assessed by calculating the κ coefficient. RESULTS: The SDAVF site was the cervical region in one patient, the thoracic region in 12 patients, the lumbar region in two, and the sacral region in one. For the visualization of abnormal vessels, the mean score was significantly higher for 3D CISS than the other sequences (P < 0.05). In 12 of 16 cases (75%) both readers made definite positive findings on additional 3D-CISS images. Interobserver agreement was excellent for 3D CISS images (κ = 1.0), good for T1WI (κ = 0.78; 95% confidence interval [CI] 0.54-1.00) and T2WI (κ = 0.74; 95% CI 0.48-1.00) and moderate for contrast-enhanced T1WI (CET1WI) (κ = 0.50; 95% CI 0.21-0.80). CONCLUSION: For the assessment of abnormal vessels of SDAVF, the 3T 3D CISS sequence adds value to conventional MRI.

Flow diversion of a recurrent, iatrogenic basilar tip aneurysm in a pediatric patient: case report.

Endoscopic third ventriculostomy (ETV) is a common treatment for noncommunicating hydrocephalus. Although rare, vascular injury and traumatic pseudoaneurysm development during ETV have been reported. The authors present the case of a 13-year-old boy who underwent repeat ETV (rETV) for shunt and ETV failure, and who suffered an intraoperative subarachnoid hemorrhage due to iatrogenic injury to the basilar tip, with subsequent development of a pseudoaneurysm. Despite initial primary coil embolization, the aneurysm recurred and was definitively treated with flow diversion. In this report, the authors review complication rates associated with ETV and rETV as well as the emerging use of flow diversion and its applications in vessel reconstruction within the pediatric population.

The relationship of dose to nerve volume in predicting pain recurrence after stereotactic radiosurgery in trigeminal neuralgia.

OBJECTIVE Approximately 75%-92% of patients with trigeminal neuralgia (TN) achieve pain relief after Gamma Knife surgery (GKS), although a proportion of these patients will experience recurrence of their pain. To evaluate the reasons for durability or recurrence, this study determined the impact of trigeminal nerve length and volume, the nerve dose-volume relationship, and the presence of neurovascular compression (NVC) on pain outcomes after GKS for TN. METHODS Fifty-eight patients with 60 symptomatic nerves underwent GKS for TN between 2013 and 2015, including 15 symptomatic nerves secondary to multiple sclerosis (MS). High-resolution MRI was acquired the day of GKS. The median maximum dose was 80 Gy for initial GKS and 65 Gy for repeat GKS. NVC, length and volume of the trigeminal nerve within the subarachnoid space of the posterior fossa, and the ratio of dose to nerve volume were assessed as predictors of recurrence. RESULTS Follow-up was available on 55 patients. Forty-nine patients (89.1%) reported pain relief (Barrow Neurological Institute [BNI] Grades I-IIIb) after GKS at a median duration of 1.9 months. The probability of maintaining pain relief (BNI Grades I-IIIb) without requiring resumption or an increase in medication was 93% at 1 year and 84% at 2 years for patients without MS, and 68% at 1 year and 51% at 2 years for all patients. The nerve length, nerve volume, target distance from the brainstem, and presence of NVC were not predictive of pain recurrence. Patients with a smaller volume of nerve (< 35% of the total nerve volume) that received a high dose (≥ 80% isodose) were less likely to experience recurrence of their TN pain after 1 year (mean time to recurrence: < 35%, 32.2 ± 4.0 months; > 35%, 17.9 ± 2.8 months, log-rank test, χ2 = 4.3, p = 0.039). CONCLUSIONS The ratio of dose to nerve volume may predict recurrence of TN pain after GKS. Prospective studies are needed to determine the optimal dose to nerve volume ratio and whether this will result in longer pain-free outcomes.