Thyroid ima artery embolization for the treatment of Graves' disease and thyroid storm.

Graves' disease may be managed with thyroid embolization when other traditional strategies are less suitable. To date, no reports exist on the embolization of the thyroid ima artery for Graves' disease or the outcomes of this procedure. Here, we present a safe and successful report of thyroid ima artery embolization in a neutropenic patient with thyroid storm. A 30-year-old female with a history of Graves' disease presented to a community hospital with heat intolerance, anxiousness, tachycardia, and tachypnea. Further laboratory testing prompted the diagnosis of thyroid storm. Embolization of the thyroid was chosen for management because total thyroidectomy risked infection in the setting of methimazole-induced neutropenia. The patient's thyroid ima artery was significantly enlarged and had a large perfusion distribution across the thyroid. It was selected for embolization, along with the right superior thyroid artery, and successfully resulted in a 60% reduction of thyroid perfusion. No complications resulted from this procedure. Although the prevalence of patients with thyroid ima artery is low, this artery can be safely and effectively embolized for the management of Graves' disease and thyroid storm.

High variability in physician estimations of flow-diverting stent deployment versus PreSize Neurovascular software simulation: a comparison study.

BACKGROUND: Physician variablity in preoperative planning of endovascular implant deployment and associated inaccuracies have not been documented. This study aimed to quantify the variability in accuracy of physician flow diverter (FD) planning and directly compares it with PreSize Neurovascular (Oxford Heartbeat Ltd) software simulations. METHODS: Eight experienced neurointerventionalists (NIs), blinded to procedural details, were provided with preoperative 3D rotational angiography (3D-RA) volumetric data along with images annotated with the distal landing location of a deployed Surpass Evolve (Stryker Neurovascular) FD from 51 patient cases. NIs were asked to perform a planning routine reflecting their normal practice and estimate the stent's proximal landing using volumetric data and the labeled dimensions of the FD used. Equivalent deployed length estimation was performed using PreSize software. NI- and software-estimated lengths were compared with postprocedural observed deployed stent length (control) using Bland-Altman plots. NI assessment agreement was assessed with the intraclass correlation coefficient (ICC). RESULTS: The mean accuracy of NI-estimated deployed FD length was 81% (±15%) versus PreSize's accuracy of 95% (±4%), demonstrating significantly higher accuracy for the software (p<0.001). The mean absolute error between estimated and control lengths was 4 mm (±3.5 mm, range 0.03-30.2 mm) for NIs and 1 mm (±0.9 mm, range 0.01-3.9 mm) for PreSize. No discernable trends in accuracy among NIs or across vasculature and aneurysm morphology (size, vessel diameter, tortuousity) were found. CONCLUSIONS: The study quantified experienced physicians' significant variablity in predicting an FD deployment with current planning approaches. In comparison, PreSize-simulated FD deployment was consistently more accurate and reliable, demonstrating its potential to improve standard of practice.

Online interactive medical neuroimaging exercise to identify human brain structures.

A persisting need remains for developing methods for inspiring and teaching undergraduate medical students to quickly learn to identify the hundreds of human brain structures, tracts and spaces that are clinically relevant (viewed as three-dimensional volumes or two-dimensional neuroimages), and to accomplish this with the option of virtual on-line methods. This notably includes teaching the essentials of recommended diagnostic radiology to allow students to be familiar with patient neuroimages routinely acquired using magnetic resonance imaging (MRI) and computed tomography (CT). The present article includes a brief example video plus details a clinically oriented interactive neuroimaging exercise for first year medical students (MS1s) in small groups, conducted with instructors either in-person or as an entirely online virtual event. This "find-the-brain-structure" (FBS) event included teaching students to identify brain structures and other regions of interest in the central nervous system (and potentially in head and neck gross anatomy), which are traditionally taught using brain anatomy atlases and anatomical specimens. The interactive, small group exercise can be conducted in person or virtually on-line in as little as 30 min depending on the scope of objectives being covered. The learning exercise involves coordinated interaction between MS1s with one or several non-clinical faculty and may include one or several physicians (clinical faculty and/or qualified residents). It further allows for varying degrees of instructor interaction online and is easy to convey to instructors who do not have expertise in neuroimaging. Anonymous pre-event survey (n = 113, 100% response rate) versus post-event surveys (n = 92, 81% response rate) were attained from a cohort of MS1s in a neurobiology course. Results showed multiple statistically significant group-level shifts in response to several of the questions, showing an increase in MS1 confidence with reading MRI images (12% increase shift in mean, p < 0.001), confidence in their approaching physicians for medical training (9%, p < 0.01), and comfort levels in working online with virtual team-based peers and with team-based faculty (6%, p < 0.05). Qualitative student feedback revealed highly positive comments regarding the experience overall, encouraging this virtual medium as a desirable educational approach.

Endoscopic Endonasal Orbital Apex Decompression for Carotid Cavernous Fistula.

SIGNIFICANCE STATEMENT: This case report demonstrates a novel approach to treating a rare indirect carotid cavernous fistula (CCF) and associated abducens palsy. Although endovascular treatment is the standard of care in the management of CCFs, it was contraindicated in this patient. Instead, she underwent an endoscopic endonasal approach (EEA) with decompression of the medial orbital apex, including the cavernous sinus and optic nerve, with complete resolution of headache, lateral gaze palsy, and diplopia within 2 months.

Semi-automated cerebral aneurysm segmentation and geometric analysis for WEB sizing utilizing a cloud-based computational platform.

BACKGROUND: Accurate aneurysm measurements are important for selecting the WEB device. The objective was to validate a cloud-based platform, SurgicalPreview (SP) against manual measurements for aneurysm analysis. METHODS: Two sets of measurements each for SP and manual methods were obtained for 40 aneurysms. Reliability and agreement were assessed with intra-class correlation coefficient (ICC) and Bland-Altman plots respectively. Kappa coefficient was used to assess agreement for predicting WEB size. RESULTS: There was good reliability for repeat SP measurements: aneurysm diameter (ICC-1, 95%CI 0.98-1), height (ICC-1, 95%CI 0.99-1) and neck diameter (ICC-0.96, 95%CI 0.93-0.98). There was good reliability for the two manual diameter (ICC-0.97, 95%CI 0.9-0.97) and height (ICC-0.93, 95%CI 0.87-0.96) measurements and moderate for neck diameter (ICC-0.76, 95%CI 0.54-0.87). There was greater agreement for SP versus manual repeat measurements on Bland-Altman plots. Reliability between the SP and manual methods was good for aneurysm diameter (ICC-0.98, 95%CI 0.95-1) and height (ICC-0.96, 95%CI-0.93-0.98) and moderate for neck. (ICC-0.6, 95%CI -0.22-0.87). The Bland-Altman plots confirmed better agreement between the two methods for the aneurysm diameter and height than the neck. There was strong agreement between the methods for predicting the WEB diameter (Kappa-0.84, 95%CI 0.71-0.97) and moderate for predicting WEB height (Kappa-0.66, 95%CI 0.43-0.89). There was moderate agreement for predicted versus deployed WEB diameter: SP (Kappa-0.56, 95%CI 0.38-0.74), Manual (Kappa-0.53, 95%CI 0.34-0.71). CONCLUSION: The SurgicalPreview® had greater agreement for repeat measurements. There was good reliability between the two methods for predicting WEB diameter and height and moderate agreement between predicted versus deployed WEB diameter.

Woven EndoBridge device for ruptured aneurysms: perioperative results of a US multicenter experience.

BACKGROUND: The Woven EndoBridge (WEB) device is approved in the USA for treatment of unruptured wide-neck bifurcation aneurysms. However, the safety and effectiveness of the WEB device in the treatment of ruptured intracranial aneurysms is not clear. We aim to evaluate the perioperative safety and effectiveness of the WEB device in patients with ruptured intracranial aneurysms. METHODS: This retrospective study, conducted at eight centers in the USA, included patients with ruptured intracranial aneurysms treated with the WEB device in the setting of subarachnoid hemorrhage (SAH). Safety outcomes included intraoperative complications such as vessel perforation, thromboembolic events, and postoperative hemorrhagic or thromboembolic complications based on radiologic imaging. The primary effectiveness outcome was adequate (complete and neck remnant) aneurysm occlusion, according to the Raymond-Roy classification. RESULTS: A total of 91 patients with 94 ruptured intracranial aneurysms were included (mean age 57.7±15.2 years; 68.1% women; 82.9% wide-necked). Aneurysms were located in the anterior communicating artery (42/94, 44.6%), middle cerebral artery (16/94, 17%), and basilar artery (15/94, 16%). Adequate occlusion was achieved in 48.8% (41/84) and 80.0% (40/50) at discharge and last follow-up (mean of 3.4 months), respectively. At discharge, procedural-related morbidity was 3.3% (3/91) and there was no procedure-related mortality. No re-rupture or delayed aneurysm rupture was observed. CONCLUSIONS: This study demonstrates the perioperative safety and effectiveness of the WEB device for the treatment of patients with ruptured intracranial aneurysms in the setting of SAH, with low periprocedural morbidity and mortality. Long-term follow-up is warranted.

Spinal dural fistula evaluation using 4-Dimensional intra-aortic spinal CTAngiography in a hybrid angiography suite.

Intra-aortic CT Angiography (IA-CTA) is a relatively new technique that shows promise in efficient diagnosis and evaluation of the angioarchitecture of spinal dural arteriovenous fistulae(sdAVF). The authors document the first reported use of a 4D-CT and C-arm fluoroscope in a hybrid interventional suite to evaluate a sdAVF. Time resolved IA-CTA is clinically feasible in the evaluation of sdAVF, has higher temporal resolution as compared to standard IA-CTA and reduced contrast load, radiation dose and potential for procedural complications as compared to standard spinal angiography.

Comparison of operating room variables, radiation exposure and implant costs for WEB versus stent assisted coiling for treatment of wide neck bifurcation aneurysms.

BACKGROUND: The WEB device offers another option for treating wide neck bifurcation aneurysms (WNBA). The objective was to compare procedure variables, radiation and implant cost between WEB and stent assisted coiling (SAC) for WNBA. METHODS: A retrospective comparison of similarly sized WNBA treated with SAC or WEB over 5-years was performed. The operating room (arrival-departure), anesthesia (intubation-extubation), procedure duration (puncture-closure), fluoroscopy time and radiation dose(m-Gy) were recorded from the patients' charts. Implant cost per case of all implants (stents, coils, WEB) that were opened whether deployed or not was captured including any coils used in the WEB cases. The implant cost represented the true cost incurred by the institution. RESULTS: There were 46 WEB and 41 SAC cases with no significant difference in aneurysm size. There were more MCA and ACOMM (p = 0.005) and more ruptured aneurysms (p = 0.02) in the WEB group. Regarding procedure variables (hours:minutes): Operating room time WEB 2:31 (±0:37) versus SAC 3:41 (±0:50) (p < 0.0001); anesthesia duration WEB 2:05 (±0:31) versus SAC 3:13 (±0:51) (p < 0.0001) and procedure duration WEB 1:16 (±0:29) versus SAC 2:09 (±0:46) (p < 0.0001). Regarding radiation: Fluoroscopy time WEB 0:34 (±0:18) versus SAC 1:06 (±0:35) (p < 0.0001) and radiation dose WEB 2392(±1086)m-Gy versus SAC 3442 (±1528)m-Gy (p = 0.0007). The implant cost was $17,028(±$5,527) for the WEB versus $23,813 (±$7,456) for the SAC group (p < 0.0001). CONCLUSION: The WEB group had significantly shorter operating room, procedure and anesthesia duration compared to the SAC group. The radiation dose and fluoroscopy time was lower for the WEB group. The total implant cost per case was significantly lower for the WEB versus the SAC group.

Embolization of a Superior Thyroid Artery Hemorrhage after Fine-Needle Aspiration Biopsy of a Thyroid Nodule.

Fine-needle aspiration biopsy (FNAB) is a procedure completed thousands of times daily across the world as an efficacious and safe way to evaluate thyroid nodules. Complications of an FNAB typically range from patient intolerance to small intrathyroidal hematomas. In rare situations, an FNA may result in significant bleeding leading to airway compromise or significant blood loss. In this case report, a patient underwent an FNAB and developed an arterial bleed leading to an intrathyroidal hematoma and airway compromise requiring intubation. This case report is unique in that it identifies the source of bleeding, exemplifies the complications of a large intrathyroidal hematoma, and describes subsequent treatment of both the arterial bleed and the hematoma.

Early postmarket results with PulseRider for treatment of wide-necked intracranial aneurysms: a multicenter experience.

OBJECTIVE: Traditionally, stent-assisted coiling and balloon remodeling have been the primary endovascular treatments for wide-necked intracranial aneurysms with complex morphologies. PulseRider is an aneurysm neck reconstruction device that provides parent vessel protection for aneurysm coiling. The objective of this study was to report early postmarket results with the PulseRider device. METHODS: This study was a prospective registry of patients treated with PulseRider at 13 American neurointerventional centers following FDA approval of this device. Data collected included clinical presentation, aneurysm characteristics, treatment details, and perioperative events. Follow-up data included degree of aneurysm occlusion and delayed (> 30 days after the procedure) complications. RESULTS: A total of 54 aneurysms were treated, with the same number of PulseRider devices, across 13 centers. Fourteen cases were in off-label locations (7 anterior communicating artery, 6 middle cerebral artery, and 1 A1 segment anterior cerebral artery aneurysms). The average dome/neck ratio was 1.2. Technical success was achieved in 52 cases (96.2%). Major complications included the following: 3 procedure-related posterior cerebral artery strokes, a device-related intraoperative aneurysm rupture, and a delayed device thrombosis. Immediately postoperative Raymond-Roy occlusion classification (RROC) class 1 was achieved in 21 cases (40.3%), class 2 in 15 (28.8%), and class 3 in 16 cases (30.7%). Additional devices were used in 3 aneurysms. For those patients with 3- or 6-month angiographic follow-up (28 patients), 18 aneurysms (64.2%) were RROC class 1 and 8 (28.5%) were RROC class 2. CONCLUSIONS: PulseRider is being used in both on- and off-label cases following FDA approval. The clinical and radiographic outcomes are comparable in real-world experience to the outcomes observed in earlier studies. Further experience is needed with the device to determine its role in the neurointerventionalist's armamentarium, especially with regard to its off-label use.

Therapeutic nihilism of neurological diseases: A comparative qualitative study.

OBJECTIVE: The notion of therapeutic nihilism may lead to early removal of care based upon perceived poor prognosis. The goal of this study was to examine if differences for nihilism perspectives exist between professions and within professions at the different levels of experience and exposure to neurological conditions. METHOD: Survey methods was used to assess perception of care futility and therapeutic nihilism using six case-based scenarios followed by five questions regarding practitioner care choices and perspective. Participants were student and professional occupational and physical therapists, nurses, and doctors (n = 110). Thematic analysis was completed to determine influences on patient care. RESULTS: Six themes (quality of life, provider experience, prognosis/treatability, medical details, patient's age, and family/patient wishes) emerged that influenced treatment decisions across all participants. All provider groups reported prognosis and treatability as their number one factor for treatment decisions, then therapists mentioned QOL most, nurses cited age, and doctors said medical details. Differences between students and professionals were also apparent. DISCUSSION: The perceived ability of the patient to recover (prognosis/treatability) with medical care was the most commonly cited reason for aggressive measures, with quality of life, medical details, and patient age also representing strong themes across disciplines and level of training.

Acute Onset of Hypersomnolence and Aphasia Secondary to an Artery of Percheron Infarct and a Proposed Emergency Room Evaluation.

Artery of Percheron (AOP) is a rare anatomical variant, which supplies bilateral paramedian thalami and the rostral mesencephalon via a single dominant thalamic perforating artery arising from the P1 segment of a posterior cerebral artery. AOP infarcts can present with a plethora of neurological symptoms: altered mental status, memory impairment, hypersomnolence, coma, aphasia, and vertical gaze palsy. Given the lack of classic stroke signs, majority of AOP infarcts are not diagnosed in the emergency setting. Timely diagnosis of an acute bilateral thalamic infarct can be challenging, and this case report highlights the uncommon neurological presentation of AOP infarction. The therapeutic time window to administer IV tPA can be missed due to this delay in diagnosis, resulting in poor clinical outcomes. To initiate appropriate acute ischemic stroke management, we propose a comprehensive radiological evaluation in the emergency room for patients with a high suspicion of an AOP infarction.

An autopsy report of basilar artery aneurysm flow diversion complicated by postoperative day 3 hemorrhage from vessel rupture.

A middle-aged patient presented with posterior circulation symptoms attributable to a large eccentric basilar trunk aneurysm. The planned treatment was flow diversion with loose coil packing which was successfully performed using a Pipeline Flex device deployed from the basilar to the left posterior cerebral artery. The complete procedure including live biplane fluoroscopy was digitally recorded. The patient had symptomatic improvement postoperatively and was discharged on day 1. The patient suffered a cardiac arrest on postoperative day 3 secondary to massive intraventricular and subarachnoid hemorrhage. An aneurysm rupture was suspected; however, postmortem examination showed an intact aneurysm sac. The hemorrhage was attributed to a small focal rent in the distal basilar artery next to an atheromatous plaque. The Pipeline device was visible through the rent. This is an autopsy report documenting an injury to the parent artery and not the aneurysm as a source of fatal delayed subarachnoid hemorrhage following flow diversion.

The 'bendy' basilar: progressive aneurysm tilting and arterial deformation can be a delayed outcome after coiling of large basilar apex aneurysms.

BACKGROUND: Morphological changes in the basilar artery and the artery-aneurysm relationship following coiling of large basilar apex aneurysms may induce morbidity. METHODS: The basilar artery radius-of-curvature was measured along its center line on volumetrically reconstructed images formatted along the plane of curvature. The aneurysm-tilt-angle was measured between the distal basilar and the vertical long axis of the aneurysm. The measurements were compared between small (<10 mm) and large (≥10 mm) aneurysms on baseline and follow-up studies. The volume (mm3) and mass (g) of the deployed coils was also compared. RESULTS: Among 94 consecutive aneurysms, 62 (66%) were <10 mm and 32 (34%) were ≥10 mm. The mean aneurysm size and volume was 9 mm (±4) and 507 mm3(±1366) respectively. The median aneurysm follow-up was 24 months (IQR 6-59). There was no difference between the groups based on age, gender, or associated comorbidities. The coil mass was 0.4 g (±0.2) for aneurysms <10 mm and 1.9 g (±1.6) for aneurysms ≥10 mm (P<0.0001). The total coil volume was 32 (±20) mm3 for aneurysms <10 mm and 187 (±172) mm3 for aneurysms ≥10 mm (P<0.0001). Aneurysms ≥10 mm tilted 13.5o (±14.4) compared with 1.1o (±2.8) for aneurysms <10 mm (P<0.0001). The basilar artery became more curved by 1.3 (±9.4) mm for aneurysms ≥10 mm and 0.25 (±2.1) mm for aneurysms <10 mm (P=0.0002). Other than size of the coiled aneurysms no other factors correlated with the geometrical changes. CONCLUSION: Large coiled basilar apex aneurysms may be more prone to aneurysm tilting and bending of the basilar artery. Speculative causes include the weight of the coil mass and the biomechanical forces exerted on the coiled aneurysm.

Rare Phenomenon of Limb-shaking TIA, Resolved With Intracranial Wingspan Stenting.

OBJECTIVE: Illustrates the importance of differentiating limb-shaking transient ischemic attack (LS-TIA) from focal seizures and carefully selecting patients for intracranial stenting. BACKGROUND: LS-TIA is associated with severe carotid stenosis or occlusion, often precipitated by cerebral hypoperfusion. A case study of 313 patients with symptomatic intracranial artery stenosis/occlusion reported 11% with LS-TIA. In our literature search, we did not find any other cases of successful treatment of LS-TIA with an intracranial Wingspan stent. DESIGN/METHODS: A 66-year-old woman with a history of atrial fibrillation on anticoagulation, hypertension, hyperlipidemia and left middle cerebral artery (MCA) stroke followed by a left internal carotid artery (ICA) endarterectomy presented with transient repetitive involuntary movements (TRIMs) over her right upper and lower limbs. She described episodes of numbness followed by TRIMs over the right side of her body lasting for 1 to 2 minutes. TRIMs occurred only while standing and usually resolved on sitting or lying down. RESULTS: Conventional angiogram showed severe stenosis of left supraclinoid ICA and proximal MCA. Brain single photon emission computed tomography scan showed impaired vascular reserve in the left MCA territory. An ambulatory electroencephalogram captured TRIMs without epileptiform discharges. She continued to have symptoms with no improvement over a period of 3 months on maximal medical management. She underwent successful endovascular treatment with the Wingspan stent system in the left M1 segment and terminal ICA. Following the revascularization procedure, her symptoms resolved. CONCLUSIONS: It is vitally important to differentiate LS-TIA from focal seizures. This is the first documented case report of complete resolution of LS-TIA symptoms following an intracranial Wingspan stenting.

An autopsy report of basilar artery aneurysm flow diversion complicated by postoperative day 3 hemorrhage from vessel rupture.

A middle-aged patient presented with posterior circulation symptoms attributable to a large eccentric basilar trunk aneurysm. The planned treatment was flow diversion with loose coil packing which was successfully performed using a Pipeline Flex device deployed from the basilar to the left posterior cerebral artery. The complete procedure including live biplane fluoroscopy was digitally recorded. The patient had symptomatic improvement postoperatively and was discharged on day 1. The patient suffered a cardiac arrest on postoperative day 3 secondary to massive intraventricular and subarachnoid hemorrhage. An aneurysm rupture was suspected; however, postmortem examination showed an intact aneurysm sac. The hemorrhage was attributed to a small focal rent in the distal basilar artery next to an atheromatous plaque. The Pipeline device was visible through the rent. This is an autopsy report documenting an injury to the parent artery and not the aneurysm as a source of fatal delayed subarachnoid hemorrhage following flow diversion.

The potential dangers of neck manipulation & risk for dissection and devastating stroke: An illustrative case & review of the literature.

Chiropractic cervical manipulation is a common practice utilized around the world. Most patients are never cleared medically for manipulation, which can be devastating for those few who are at increased risk for dissections. The high velocity thrust used in cervical manipulation can produce significant strain on carotid and vertebral vessels. Once a dissection has occurred, the risk of thrombus formation, ischemic stroke, paralysis, and even death is drastically increased. In this case report, we highlight a case of a 32-year-old woman who underwent chiropractic manipulation and had vertebral artery dissection with subsequent brainstem infarct. She quickly deteriorated and passed away shortly after arrival to the hospital. Although rare, one in 48 chiropractors have experienced such an event. We utilize this case to highlight the risk associated with cervical manipulation and urge open dialogue between chiropractors and physicians. Receiving medical clearance prior to cervical manipulation in potential at risk patients would drastically reduce morbidity and mortality.

A population-based incidence of M2 strokes indicates potential expansion of large vessel occlusions amenable to endovascular therapy.

BACKGROUND: M2 occlusions may result in poor outcomes and potentially benefit from endovascular therapy. Data on the rate of M2 strokes is lacking. METHODOLOGY: Patients with acute ischemic stroke discharged over a period of 3 years from a tertiary level hospital in the 'stroke belt' were evaluated for M2 occlusions on baseline vascular imaging. Regional and national incidence was calculated from discharge and multicounty data. RESULTS: There were 2739 ICD-9 based AIS discharges. M2 occlusions in 116 (4%, 95% CI 3.5% to 5%) patients constituted the second most common occlusion site. The median National Institute of Health Stroke Scale (NIHSS) score was 12 (IQR 5-18). Good outcomes were observed in 43% (95% CI 34% to 53%), poor outcomes in 57% (95% CI 47% to 66%), and death occurred in 27% (95% CI 19% to 37%) of patients. Receiver operating characteristics curves showed the NIHSS to be predictive of outcomes (area under the curve 0.829, 95% CI 0.745 to 0.913, p<0.0001). An NIHSS score ≥9 was the optimal cut-off point for predicting poor outcomes (sensitivity 85.7%, specificity 67.4%). 71 (61%) patients had an NIHSS score ≥9 and 45 (39%) an NIHSS score <9. The rate of good-outcome was 22.6% for NIHSS score ≥9 versus 78.4% for NIHSSscore <9 (OR=0.08, 95% CI 0.03 to 0.21, p<0.0001). Mortality was 42% for NIHSS score ≥9 versus 2.7% for NIHSS score <9 (OR=26, 95% CI 3.3 to 202, p<0.0001). Infarct volume was 57 (±55.7) cm3 for NIHSS score ≥9 versus 30 (±34)cm3 for NIHSS score <9 (p=0.003). IV recombinant tissue plasminogen activator (rtPA) administered in 28 (24%) patients did not affect outcomes. The rate of M2 occlusions was 7 (95% CI 5 to 9)/100 000 people/year (3%, 95% CI 2% to 4%), giving an incidence of 21 176 (95% CI 15 282 to 29 247)/year. Combined with M1, internal carotid artery terminus and basilar artery, this yields a 'large vessel occlusion (LVO)+M2' rate of 31 (95% CI 26 to 35)/100 000 people/year and a national incidence of 99 227 (95% CI 84 004 to 112 005) LVO+M2 strokes/year. CONCLUSION: M2 occlusions can present with serious neurological deficits and cause significant morbidity and mortality. Patients with M2 occlusions and higher baseline deficits (NIHSS score ≥9) may benefit from endovascular therapy, thus potentially expanding the category of acute ischemic strokes amenable to intervention.