Transarterial embolization of an internal maxillary artery arteriovenous fistula presenting with pulsatile tinnitus.

Arteriovenous fistulae of the internal maxillary artery are exceedingly rare, with less than 30 cases reported in the literature. Most of these lesions are congenital, iatrogenic, or posttraumatic. The most common presentation of internal maxillary artery fistulae is pulsatile tinnitus and headache. Because these lesions are single-hole fistulae, they can be easily cured with endovascular techniques. The authors present a case of a patient who presented to their institution with a several-year history of pulsatile tinnitus who was found to have an internal maxillary artery arteriovenous fistula, which was treated endovascularly with transarterial coil and Onyx embolization.The video can be found here: https://youtu.be/fDZVMMwpwRc.

Timing and Predictors of T2-Lesion Resolution in Patients With Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease.

OBJECTIVES: To determine the timing and predictors of T2-lesion resolution in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). METHODS: This retrospective observational study using standard-of-care data had inclusion criteria of MOGAD diagnosis, ≥2 MRIs 12 months apart, and ≥1 brain/spinal cord T2-lesion. The median (interquartile range [IQR]) number of MRIs (82% at disease onset) per-patient were: brain, 5 (2-8); spine, 4 (2-8). Predictors of T2-lesion resolution were assessed with age- and sex-adjusted generalized estimating equations and stratified by T2-lesion size (small <1 cm; large ≥1 cm). RESULTS: We studied 583 T2-lesions (brain, 512 [88%]; spinal cord, 71 [12%]) from 55 patients. At last MRI (median follow-up 54 months [IQR 7-74]) 455 T2-lesions (78%) resolved. The median (IQR) time to resolution was 3 months (1.4-7.0). Small T2-lesions resolved more frequently and faster than large T2-lesions. Acute T1-hypointensity decreased the likelihood (odds ratio [95% CI]) of T2-lesion resolution independent of size (small: 0.23 [0.09-0.60], p = 0.002; large: 0.30 [0.16-0.55], p < 0.001), whereas acute steroids favored resolution of large T2-lesions (1.75 [1.01-3.03], p = 0.046). Notably, 32/55 (58%) T2-lesions resolved without treatment. DISCUSSION: The high frequency of spontaneous T2-lesion resolution suggests that this represents MOGAD's natural history. The speed of T2-lesion resolution and influence of size, corticosteroids, and T1-hypointensity on this phenomenon gives insight into MOGAD pathogenesis.

Clinical and imaging outcomes of 100 patients with cerebrospinal fluid-venous fistulas treated by transvenous embolization.

BACKGROUND: Cerebrospinal fluid-venous fistulas (CSFVF) are a common cause of spontaneous intracranial hypotension (SIH). Transvenous embolization has emerged as a reliable treatment option. We review the clinical presentation, imaging, and clinical outcomes of 100 consecutive CSFVF patients who underwent embolization over 2 years. METHODS: Baseline clinical characteristics, imaging findings (including Bern SIH score), technical outcomes, and long-term imaging and clinical outcomes were collected. All patients had at least 3 months of clinical follow-up and had baseline MRI. 99/100 patients underwent follow-up imaging at ≥3 months post-treatment. RESULTS: 100 patients were included. Mean imaging and clinical follow-up duration was 8.3±7.7 months and 15.0±6.8 months, respectively. The mean duration of symptoms before embolization was 40.9±52 months. Mean baseline Bern SIH score was 5.9±3.3. The most common baseline symptoms were headache (96 patients), tinnitus (55 patients), and cognitive dysfunction (44 patients). Technical success rate was 100%. Mean post-treatment Bern SIH score was 0.9±1.6 (P<0.0001). Following treatment, 95% of patients reported significant improvement or resolution in symptoms (58 patients reporting resolution and 37 reporting improvement). 5 patients reported no improvement. There were no major procedural or periprocedural complications. 10 patients had minor procedural complications that did not result in any change in management (Onyx emboli, venous perforation). 19 patients had rebound intracranial hypertension requiring acetazolamide therapy. 7 patients had recurrent fistula at the initially treated level. CONCLUSIONS: Transvenous embolization of CSFVF in SIH patients is safe and effective with a 95% treatment response, significant improvement in imaging outcomes, and a very low rate of complications.

Tumefactive Demyelination in MOG Ab-Associated Disease, Multiple Sclerosis, and AQP-4-IgG-Positive Neuromyelitis Optica Spectrum Disorder.

BACKGROUND AND OBJECTIVES: Studies on tumefactive brain lesions in myelin oligodendrocyte glycoprotein-immunoglobulin G (IgG)-associated disease (MOGAD) are lacking. We sought to characterize the frequency clinical, laboratory, and MRI features of these lesions in MOGAD and compare them with those in multiple sclerosis (MS) and aquaporin-4-IgG-positive neuromyelitis optica spectrum disorder (AQP4+NMOSD). METHODS: We retrospectively searched 194 patients with MOGAD and 359 patients with AQP4+NMOSD with clinical/MRI details available from the Mayo Clinic databases and included those with ≥1 tumefactive brain lesion (maximum transverse diameter ≥2 cm) on MRI. Patients with tumefactive MS were identified using the Mayo Clinic medical record linkage system. Binary multivariable stepwise logistic regression identified independent predictors of MOGAD diagnosis; Cox proportional regression models were used to assess the risk of relapsing disease and gait aid in patients with tumefactive MOGAD vs those with nontumefactive MOGAD. RESULTS: We included 108 patients with tumefactive demyelination (MOGAD = 43; AQP4+NMOSD = 16; and MS = 49). Tumefactive lesions were more frequent among those with MOGAD (43/194 [22%]) than among those with AQP4+NMOSD (16/359 [5%], p < 0.001). Risk of relapse and need for gait aid were similar in tumefactive and nontumefactive MOGAD. Clinical features more frequent in MOGAD than in MS included headache (18/43 [42%] vs 10/49 [20%]; p = 0.03) and somnolence (12/43 [28%] vs 2/49 [4%]; p = 0.003), the latter also more frequent than in AQP4+NMOSD (0/16 [0%]; p = 0.02). The presence of peripheral T2-hypointense rim, T1-hypointensity, diffusion restriction (particularly an arc pattern), ring enhancement, and Baló-like or cystic appearance favored MS over MOGAD (p ≤ 0.001). MRI features were broadly similar in MOGAD and AQP4+NMOSD, except for more frequent diffusion restriction in AQP4+NMOSD (10/15 [67%]) than in MOGAD (11/42 [26%], p = 0.005). CSF analysis revealed less frequent positive oligoclonal bands in MOGAD (2/37 [5%]) than in MS (30/43 [70%], p < 0.001) and higher median white cell count in MOGAD than in MS (33 vs 6 cells/µL, p < 0.001). At baseline, independent predictors of MOGAD diagnosis were the presence of somnolence/headache, absence of T2-hypointense rim, lack of T1-hypointensity, and no diffusion restriction (Nagelkerke R 2 = 0.67). Tumefactive lesion resolution was more common in MOGAD than in MS or AQP4+NMOSD and improved model performance. DISCUSSION: Tumefactive lesions are frequent in MOGAD but not associated with a worse prognosis. The clinical, MRI, and CSF attributes of tumefactive MOGAD differ from those of tumefactive MS and are more similar to those of tumefactive AQP4+NMOSD with the exception of lesion resolution, which favors MOGAD.

Incremental diagnostic yield and clinical outcomes of lateral decubitus CT myelogram immediately following negative lateral decubitus digital subtraction myelogram.

INTRODUCTION: Spontaneous intracranial hypotension (SIH) caused by a spinal cerebrospinal fluid (CSF) leak classically presents with orthostatic headache. Digital subtraction myelography (DSM) has a well-established diagnostic yield in the absence of extradural spinal collection. At our institution, DSM is followed by lateral decubitus CT myelogram (LDCTM) in the same decubitus position to increase diagnostic yield of the combined study. We evaluated the incremental diagnostic yield of LDCTM following negative DSM and reviewed patient outcomes. METHODS: Retrospective review of consecutive DSMs with subsequent LDCTM from April 2019 to March 2021 was performed. Combined reports were reviewed, and studies with positive DSMs were excluded. Of the exams with negative DSM, only studies with LDCTM reports identifying potential leak site were included. Interventions and follow-up clinical notes were reviewed to assess symptoms improvement following treatment. RESULTS: Of the 83 patients with negative DSMs, 11 (13.2%) had positive leak findings on LDCTMs, and 21 (25.3%) were equivocal. Of 11 positive LDCTMs, 6 leaks were nerve sheath tears (NSTs) and 5 were CSF-venous fistulas (CVFs). 10/11 (90.9%) had intervention and follow-up, with 9/10 (90%) having positive clinical outcome. Of the 21 equivocal LDCTM patients (19 CVFs and 2 NSTs), 15 (71.4%) had interventions and follow-up, with 3/15 (20.0%) with positive clinical outcomes. CONCLUSION: LDCTM following negative DSM has an incremental diagnostic yield up to 38.6%, with up to 14.5% of positive patient outcomes following treatment. LDCTM should be considered after DSM to maximize diagnostic yield of the combined exam.

Diagnostic Performance of Decubitus Photon-Counting Detector CT Myelography for the Detection of CSF-Venous Fistulas.

BACKGROUND AND PURPOSE: CSF-venous fistulas are a common cause of spontaneous intracranial hypotension. Lateral decubitus digital subtraction myelography and CT myelography are the diagnostic imaging standards to identify these fistulas. Photon-counting CT myelography has technological advantages that might improve CSF-venous fistula detection, though no large studies have yet assessed its diagnostic performance. We sought to determine the diagnostic yield of photon-counting detector CT myelography for detection of CSF-venous fistulas in patients with spontaneous intracranial hypotension. MATERIALS AND METHODS: We retrospectively searched our database for all decubitus photon-counting detector CT myelograms performed at our institution since the introduction of the technique in our practice. Per our institutional workflow, all patients had prior contrast-enhanced brain MR imaging and spine MR imaging showing no extradural CSF. Two neuroradiologists reviewed preprocedural brain MRIs, assessing previously described findings of intracranial hypotension (Bern score). Additionally, 2 different neuroradiologists assessed each myelogram for a definitive or equivocal CSF-venous fistula. The yield of photon-counting detector CT myelography was calculated and stratified by the Bern score using low-, intermediate-, and high-probability tiers. RESULTS: Fifty-seven consecutive photon-counting detector CT myelograms in 57 patients were included. A single CSF-venous fistula was definitively present in 38/57 patients. After we stratified by the Bern score, a definitive fistula was seen in 56.0%, 73.3%, and 76.5% of patients with low-, intermediate-, and high-probability brain MR imaging, respectively. CONCLUSIONS: Decubitus photon-counting detector CT myelography has an excellent diagnostic performance for the detection of CSF-venous fistulas. The yield for patients with intermediate- and high-probability Bern scores is at least as high as previously reported yields of decubitus digital subtraction myelography and CT myelography using energy-integrating detector scanners. The yield for patients with low-probability Bern scores appears to be greater compared with other modalities. Due to the retrospective nature of this study, future prospective work will be needed to compare the sensitivity of photon-counting detector CT myelography with other modalities.

Frequency of Asymptomatic Optic Nerve Enhancement in a Large Retrospective Cohort of Patients With Aquaporin-4+ NMOSD.

BACKGROUND AND OBJECTIVES: Asymptomatic or persistent optic nerve enhancement in aquaporin-4 (AQP4)-immunoglobulin G (IgG)-positive neuromyelitis optica spectrum disorder (NMOSD) is thought to be rare. Improved understanding may have important implications for assessment of treatment efficacy in clinical trials and in clinical practice. Our objective was to characterize NMOSD interattack optic nerve enhancement. METHODS: This was a retrospective cohort study performed between 2000 and 2019 (median follow-up 5.5 [range 1-35] years) of patients with AQP4-IgG-positive optic neuritis (ON) evaluated at Mayo Clinic. MRI orbits were reviewed by a neuroradiologist, neuro-ophthalmologist, and neuroimmunologist blinded to the clinical history. Interattack optic nerve enhancement (>30 days after attack) was measured. The correlation between interattack enhancement and Snellen visual acuity (VA), converted to logarithm of the minimum angle of resolution (logMAR), at attack and at follow-up were assessed. RESULTS: A total of 198 MRI scans in 100 patients with AQP4-IgG+ NMOSD were identified, with 107 interattack MRIs from 78 unique patients reviewed. Seven scans were performed before any ON (median 61 days before attack [range 21-271 days]) and 100 after ON (median 400 days after attack [33-4,623 days]). Optic nerve enhancement was present on 18/107 (16.8%) interattack scans (median 192.5 days from attack [33-2,943]) of patients with preceding ON. On 15 scans, enhancement occurred at the site of prior attacks; the lesion location was unchanged, but the lesion length was shorter. Two scans (1.8%) demonstrated new asymptomatic lesions (prior scan demonstrated no enhancement). In a third patient with subjective blurry vision, MRI showed enhancement preceding detectable eye abnormalities on examination noted 15 days later. There was no difference in VA at preceding attack nadir (logMAR VA 1.7 vs 2.1; p = 0.79) or long-term VA (logMAR VA 0.4 vs 0.2, p = 0.56) between those with and without interattack optic nerve enhancement. DISCUSSION: Asymptomatic optic nerve enhancement occurred in 17% of patients with NMOSD predominantly at the site of prior ON attacks and may represent intermittent blood-brain barrier breakdown or subclinical ON. New asymptomatic enhancement was seen only in 2% of patients. Therapeutic clinical trials for NMOSD require blinded relapse adjudication when assessing treatment efficacy, and it is important to recognize that asymptomatic optic nerve enhancement can occur in patients with ON.

Diagnostic Yield of Intrathecal Gadolinium MR Myelography for CSF Leak Localization.

PURPOSE: Intrathecal gadolinium magnetic resonance (MR) myelography can be used to localize various types of spinal cerebrospinal fluid (CSF) leaks; however, its diagnostic yield is not well known. We sought to determine the diagnostic yield of MR myelography in patients with spontaneous intracranial hypotension. METHODS: A retrospective review was performed on all patients who had undergone intrathecal gadolinium MR myelography at our institution from 2002 to 2020 for suspected spinal CSF leak. The MR myelography images were reviewed for the presence or absence of a spinal CSF leak site. Images were also evaluated for the presence an extradural fluid collection. RESULTS: A total of 97 patients were included in the final cohort. The average age was 52.6 years; 67.0% were female, 4 patients underwent 2 examinations each, yielding a total of 101 MR myelograms. The source of a spinal CSF leak was localized in 14 patients. The diagnostic yield for CSF leak localization on intrathecal gadolinium MR myelography was 14/101 (13.9%) per GdM examination and 14/97 (14.4%) per patient. Among the subset of patients without extradural fluid collections, the yield was 15.7% per examination. All detected leaks were either CSF-venous fistulas or distal nerve root sleeve tears. CONCLUSION: Intrathecal gadolinium MR myelography is capable of localizing CSF-venous fistulas and distal nerve root sleeve tears; however, our data show that it has a limited diagnostic yield. We suggest that other modalities may be a better first step before attempting intrathecal gadolinium MR myelography.

Frequency of New or Enlarging Lesions on MRI Outside of Clinical Attacks in Patients With MOG-Antibody-Associated Disease.

OBJECTIVE: To determine the frequency of new or enlarging T2-hyperintense or enhancing lesions outside of clinical attacks in myelin-oligodendrocyte-glycoprotein-antibody-associated-disease (MOGAD) versus multiple sclerosis (MS) and aquaporin-4 antibody-positive-neuromyelitis-optica-spectrum-disorder (AQP4+NMOSD). DESIGN/METHODS: We retrospectively included Mayo Clinic MOGAD patients with: 1) MOG-IgG positivity by live-cell-based-assay; 2) Fulfilling proposed MOGAD diagnostic criteria; 3) Baseline and follow-up paired MRIs without interval attacks. A neurologist and neuroradiologist reviewed MRIs (T2-FLAIR brain, T2 spine, and T1-post-gadolinium brain and spine) to identify new or enlarging lesions. A MOGAD subset was then compared to MS and AQP4+NMOSD patients, based on broadly similar inter-scan intervals. RESULTS: We included 105 MOGAD patients (median age, 31 years[range, 2-80]; 60% female) with 373 paired MRIs. In total, 10/105 (9.5%) patients and 13/373 (3%) scans had one or more new T2-lesions (brain, 12/213[6%]; spine, 1/160[0.6%]) and 8/367 (2%) had enhancing lesions. New brain lesions were less in MOGAD (1/25[4%]) than MS (14/26[54%], p<0.0001) but did not differ from AQP4+NMOSD (1/13[8%], p=1.0) in subgroup analysis. New spinal lesions were rare across groups (0-4%). CONCLUSIONS: New or enlarging MRI lesions rarely develop outside of clinical attacks in MOGAD differing from MS. Surveillance MRIs in MOGAD have limited utility with implications for clinical practice and trial design.

Utility of CT venography in monitoring stent patency in idiopathic intracranial hypertension: retrospective single-center study.

BACKGROUND: Cerebral venous sinus stenting is an established treatment for patients with idiopathic intracranial hypertension (IIH), refractory to medical management and with stenotic venous sinus on conventional cerebral venography. Currently, there are no clear guidelines on optimal noninvasive imaging modality for routine post-stenting follow-up. We investigated diagnostic yield of CT venography (CTV) for evaluation of stent patency. METHODS: We reviewed our clinical database of patients with a diagnosis of IIH, who underwent stenting of stenotic transverse or transverse/sigmoid sinus junction. Patients who had follow-up CTVs after more than 30 days were included in the final study group. All CTVs were reviewed by two readers for in-stent thrombosis, extrinsic stent compression, juxta-stent stenosis, and new contralateral venous sinus stenosis. Inter-observer agreement and association of stent patency with clinical outcomes (headache and papilledema) were assessed. RESULTS: In all 36 included patients with 38 cerebral venograms for stenting, follow-up CTVs demonstrated adequate opacifications of the venous sinuses and stents for confident evaluation for in-stent thrombosis, extrinsic stent compression, juxta-stent stenosis, and new contralateral venous sinus stenosis, with inter-observer agreement coefficient of 0.7, 1.0, 0.8, and 1.0 respectively. Association between abnormal CTV and higher rates of persistent headache and lower rates of headache improvement/resolution was statistically significant (P-value of 0.01). CONCLUSION: CTV is a reliable noninvasive imaging modality for evaluation of cerebral venous sinuses and stent patency following treatment of idiopathic intracranial hypertension with venous sinus stenting and could be used as a routine follow-up study.

Sclerotherapy for low-flow vascular malformations of the orbital and periocular regions: Systematic review and meta-analysis.

Percutaneous sclerotherapy is an alternative strategy for the treatment of vascular malformations of the orbital and periorbital regions. The safety and efficacy of sclerotherapy in this setting have not been fully established. We present the results of a systematic review and meta-analysis examining the safety and efficacy of percutaneous sclerotherapy for the treatment of vascular malformations of the orbit. We searched PubMed, MEDLINE, and EMBASE from 2000 to 2018 for studies evaluating the safety and efficacy of percutaneous sclerotherapy for orbital and periorbital vascular malformations. Two independent reviewers selected studies and abstracted data. The primary outcome of this study is the efficacy of sclerotherapy which includes complete response, partial response, or no response to sclerotherapy. Data were analyzed using random-effects meta-analysis. Thirteen studies reporting on 154 patients were included. The rate of complete cure after percutaneous sclerotherapy was 54.9% (95% confidence interval [CI] = 34.2%-75.7%). The rate of emergent decompressive surgery was 3.4% (95% CI = 0.5%-6.2%), and the rate of vision loss was 2.7% (95% CI = 0.1%-5.3%). I2 values were above 50% for most outcomes indicating substantial heterogeneity. Our systematic review and meta-analysis of 13 studies and over 150 patients found that percutaneous sclerotherapy is a safe and effective treatment modality for the treatment of low-flow vascular malformations of the orbit.

Radiation dose reduction during neuroendovascular procedures.

AIM: To describe the impact of steps towards reduction of procedural doses of radiation during neuroendovascular procedures. METHODS: Phantom exposures under controlled circumstances were performed using a Rando-Alderson adult-sized head phantom. Customized imaging protocols were devised for pediatric and adult imaging and implemented in clinical use. Outcome data for estimated skin doses (ESD) and dose-area product (DAP) following pediatric and adult diagnostic and interventional procedures over 4.5 years were analyzed retrospectively. RESULTS: Dose estimates were reduced by 50% or more after introduction of customized imaging protocols in association with modification of personnel behavior compared with doses recorded with previously used vendor-recommended protocols. DISCUSSION: Substantial reductions in radiation use during neuroendovascular procedures can be achieved through a combination of equipment modification and operator behavior.

Sacroplasty: a treatment for sacral insufficiency fractures.

Sacral insufficiency fracture is a debilitating injury for which no active treatment is currently available. We present three consecutive cases of elderly patients with sacral insufficiency fractures whose symptoms were relieved immediately by treatment of the fractures by polymethylmethacrylate injections, a so-called sacroplasty.

Endovascular management of vertebrobasilar dissecting aneurysms.

BACKGROUND AND PURPOSE: Several approaches to the treatment of dissecting aneurysms of the vertebrobasilar system have been used. We evaluated our endovascular experience, which includes trapping and proximal occlusion. METHODS: Thirty-five patients with intradural vertebrobasilar dissecting aneurysms presented to our institution between 1992 and 2002. Twenty-six were treated by endovascular means and two with surgery. In the endovascular group, 14 were in a supra-posterior inferior cerebellar artery (PICA) location, and three of these extended to the vertebrobasilar junction on the initial angiogram. Ten were located in an infra-PICA location, or no antegrade flow was seen in the PICA or anterior spinal artery. Two were located at the PICA with antegrade flow preserved in the branch. Twelve lesions were treated with trapping; another 14 were initially treated with proximal occlusion techniques, two of which eventually required trapping procedures. Follow-up images were obtained within 1 year of initial treatment in 24 patients. Mean follow-up for these patients was 3.5 years. RESULTS: Initial treatments were technically successful and without complication in all 26 patients. Follow-up examinations showed complete cure in 19 of 24 patients. One patient died of global ischemia after presenting as Hunt and Hess grade 5 with subarachanoid hemorrhage. Two recurrent hemorrhages occurred in patients in the proximal occlusion group; one died, and the other underwent a trapping procedure. One patient developed contralateral vertebral dissection 24 hours after occlusion of a dissecting aneurysm of the dominant vertebral artery and died of a brain stem infarct. Another died of probable vasospasm, and the last died of an unknown cause 1 month after treatment. Two patients had recanalization despite an initial trapping procedure, both underwent further treatment. Mortality rate was 20% in the treated group (including the two patients treated surgically), with four of five deaths occurring during the initial hospital course. Mortality rate was 50% in the six patients in the untreated group who were available for follow-up. CONCLUSION: Dissecting aneurysms of the vertebrobasilar system remain high-risk lesions because of their natural history. They can be managed by endovascular methods according to aneurysm location, configuration, collateral circulation, and time of presentation. Trapping results in better prevention of rehemorrhage. Proximal occlusion can achieve occlusion without manipulation of the affected segment when more direct endovascular occlusion or stent placement cannot be performed.

Functional CT perfusion imaging in predicting the extent of cerebral infarction from a 3-hour middle cerebral arterial occlusion in a primate stroke model.

BACKGROUND AND PURPOSE: Our purpose was to determine whether cerebral perfusion functional CT (fCT), performed after endovascular middle cerebral artery (MCA) occlusion, can be used to predict final cerebral infarction extent in a primate model. METHODS: fCT with bolus tracking was performed before and 30 and 150 minutes after 3-hour digital subtraction angiography (DSA)-guided endovascular MCA occlusion in five baboons. Parametric cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) maps were constructed by voxel-by-voxel gamma variate fitting and used to determine lesion sizes. Animals were sacrificed 48 hours after the occlusion, and ex vivo MR imaging was performed. Lesion sizes on fCT and MR images were compared. RESULTS: Hypoperfusion was clearly identified on all images obtained after MCA occlusion. Thirty and 150 minutes after occlusion onset, respectively, mean lesion sizes were 737 mm(2) +/- 33 and 737 mm(2) +/- 44 for CBF, 722 mm(2) +/- 32 and 730 mm(2) +/- 43 for CBV, and 819 mm(2) +/- 14 and 847 mm(2) +/- 11 for MTT. Mean outcome infarct size on MR images was 733 mm(2) +/- 30. Measurements based on CBV and CBF (R(2) = 0.97 and 0.96, P <.001), but not MTT (R(2) = 0.40, P >.5), were highly correlated with final lesion size. CONCLUSION: An endovascular approach to MCA occlusion provides a minimally invasive, reproducible animal model for controlled studies of cerebral ischemia and infarction. Derived cerebral perfusion maps closely predict the 48-hour infarct size after 3-hour MCA occlusion.

Transcranial Doppler ultrasound: a new method of monitoring hemispheric anesthetization during the intracarotid amobarbital procedure.

BACKGROUND: Electroencephalography (EEG) is traditionally used to assess the duration of hemispheric anesthetization and to monitor return of function in the anesthetized hemisphere during the intracarotid amobarbital procedure (IAP), but EEG changes are not consistently seen. The authors evaluated the role of continuous transcranial Doppler (TCD) monitoring as an alternative to EEG. METHODS: The authors performed both continuous TCD monitoring and EEG during the IAP in 10 patients with medically intractable partial epilepsy. Mean velocities were monitored continuously in both middle cerebral arteries (MCAs), and changes in MCA velocities on continuous TCD monitoring were time locked with the EEG changes. RESULTS: The average mean MCA velocities were within normal limits bilaterally (50-85 cm/s) in all patients at baseline. Mean MCA velocites increased in all patients to 95-115 cm/s at the start of the test when the patients were asked to raise their hands and start counting. After injection of sodium amobarbital, mean MCA velocities in all patients dropped dramatically on the ipsilateral side to values of 12-39 cm/s and returned to the baseline average value when the hemiparesis recovered. In 8 patients, the duration of delta activity on EEG coincided with the time interval during which the mean MCA velocities were low on TCD monitoring. In 2 patients, despite the presence of hemiparesis clinically and a drop in mean MCA velocities on the ipsilateral side on continuous TCD monitoring, EEG remained normal on the ipsilateral side. CONCLUSIONS: Continuous TCD monitoring may be a more sensitive method than EEG in determining the duration of hemispheric anesthetization during IAP. Because the items for assessment of memory are presented during the period of hemispheric anesthetization, TCD may be useful in more precisely defining the time window for memory testing.

Occult dural arteriovenous fistula causing rapidly progressive conus medullaris syndrome and paraplegia after lumbar microdiscectomy.

BACKGROUND CONTEXT: A spinal dural arteriovenous fistula (DAVF) is a known cause of venous congestive myelopathy. These lesions are thought to be acquired. There exist two prior reports that describe DAVF presenting with slowly progressive myelopathy years after lumbar disc surgery. PURPOSE: We report the first case of a preexistent, asymptomatic DAVF that became acutely symptomatic after lumbar microdiscectomy causing rapidly progressive conus medullaris syndrome and paraplegia. STUDY DESIGN: Case report. METHODS: A 53-year-old Caucasian male presented with urinary retention, fecal incontinence, and progressive loss of function in bilateral lower extremities less than 3 months after a lumbar discectomy at an outside facility. The patient underwent microdiscectomy at L4/L5 and L5/S1 for left-sided radicular symptoms and evidence of herniated discs on magnetic resonance imaging (MRI). The patient's preoperative pain improved after the discectomy, but his bowel, bladder, and lower extremity function deteriorated steadily after discharge. Postoperative MRI showed salient serpentine vessels in the region of L1 and L2 with an enlarged T2 bright conus medullaris. Retrospective review of preoperative MRI revealed the presence of similar but less pronounced findings. A spinal arteriogram confirmed concerns of an arteriovenous malformation. The patient was transferred to our facility for definitive management of his DAVF via catheter embolization. RESULTS: Complete fistula obliteration was confirmed at the time of embolization and at 8 weeks follow-up with selective spinal angiography. The appearance of the conus medullaris normalized on follow-up MRI. The patient made a slow but significant recovery in rehabilitation. He regained the ability to independently ambulate but remains significantly disabled secondary to residual lower extremity weakness and spasticity. He continues self-catheterization for persistent neurogenic bladder dysfunction. CONCLUSIONS: This represents the first case of an occult spinal DAVF becoming acutely symptomatic after lumbar disc surgery. Although the etiology of the lesion and its symptomatic progression remains unknown, an alteration of blood flow through the DAVF as a result of surgery may have resulted in progressive venous congestive myelopathy. The present case highlights the importance of considering a spinal DAVF in the differential diagnosis of any patient with signs of myelopathy or conus medullaris syndrome after lumbar discectomy. In addition, this case underscores the gravity of recognizing subtle features that suggest the presence of an occult vascular malformation on preoperative imaging, as symptomatic progression of these lesions carries significant potential morbidity.

Ruptured anterior spinal artery aneurysm: a case report.

We present a case of a subarachnoid hemorrhage and vasospasm secondary to a ruptured anterior spinal artery aneurysm associated with a Chiari 1 malformation. To our knowledge this is the first reported spinal artery aneurysm with this association.