The authors have no acknowledgments.

NOTE: Prior to performing this procedure, obtain all required institutional approval and patient consent.
1. Surgical Technique
<ol>
	<li>Induce patient with general anesthesia.</li>
	<li>Place radial arterial line for blood pressure monitoring.</li>
	<li>Place patient in the supine position on the operating room table.</li>
	<li>After the head is clamped into the Mayfield Head holder using standard techniques for a pterional craniotomy, position the head 30&#176;-45&#176; with the ipsilateral side up towards the ceiling, except for anterior-communicating artery aneurysms in which the head is placed at 60&#186; to allow for better visualization across the interhemispheric fissure.</li>
	<li>Position the neck midline and translate anteriorly to maximize jugular venous drainage to prevent cerebral edema and then extend the head to position the ipsilateral zygoma at the highest point&#8212;this allows for frontal lobe relaxation and elevation from the orbital roof during dissection without the use of retractors.</li>
	<li>Clip the hair in preparation for standard pterional scalp incision; use about a one to two inch strip behind the hairline.</li>
	<li>Sterilely prep the skin and drape the surgical area according to standard of care.</li>
	<li>Perform a standard curved scalp incision for a pterional approach extending from the midline of the scalp behind the hairline with a gentle curve posteriorly and inferiorly towards the tragus ending it about 3 mm anterior to the tragus and at the level of the superior edge of the zygoma. Perform this incision down to the skull above the superior temporal line and to the muscle fascia at the level of the temporalis muscle.</li>
	<li>Use electrocautery for scalp hemostasis with the bipolar device.</li>
	<li>Cut the temporalis muscle down to the skull using the bovie monopolar electrocautery device.</li>
	<li>Raise a myocutaneous flap keeping the temporalis muscle attached to the undersurface of the scalp for now. Fish-hooks are used to evert the flap after the temporalis muscle is elevated from the skull using a combination of monopolar electrocautery and a periosteal elevator.</li>
	<li>Perform an inverse subfascial dissection in the avascular plane from the undersurface of the myocutaneous flap using Metzenbaum scissors, keeping the fascia and subfacsial fat pad with the scalp to avoid injury to the facial nerve.</li>
	<li>Secure the temporalis muscle posteriorly and inferiorly to expose the pterional region with &#8220;star&#8221; fishhooks.</li>
	<li>Keep all components of the myocutaneous flap moist with wetted gauze.</li>
	<li>Drill a single temporal 5 mm burr-hole at the posterior-most aspect of the planned craniotomy with a 2 mm cutting burr so that the foot plate of the side-cutting drill can be inserted into this hole and then use a side-cutting drill with a foot plate to remove the thumb-sized (approximately 3 x 4 cm) kidney-shaped craniotomy centered anteriorly around the pterion.</li>
	<li>Using a No. 1 Penfield, separate the dura on all sides of the pterion and have an assistant gently retract the dura away from the bone surface that is being drilled to minimize risk of penetrating the dura and causing cortical injury.</li>
	<li>Remove the pterion with a drill: anteriorly, until the superior and lateral aspects of the orbital roof are smooth and flattened down to the outer cortical table of bone, without entering the orbit, to maximize subfrontal exposure; medially, drill until the superior orbital fissure dura is exposed and remove any small pieces of bone that would interfere with medial exposure using either a drill bit or hand-held Lempert bone cutting device. Ensure that excellent hemostasis of all soft-tissue and bone surfaces has been obtained to avoid blood dripping into the intradural space during brain dissection and aneurysm exposure, using electrocaurtery and bone wax as needed, before opening the dura.</li>
	<li>Gently elevate the dura and use a No. 11 scalpel to penetrate the dura and then use dural scissors to create a &#8220;C-shaped&#8221; opening in the dura with the base at the pterion. Secure the dura flat against the outer cortical bone of the orbit without having redundant dural leaflets that would otherwise obscure visualization of the proximal Sylvian Fissure and subfrontal region. This can be performed by using 4-0 Surgilons sutures to tack the dura to the scalp.</li>
</ol>
2. Brain Relaxation
<ol>
	<li>Give 25-50 g of Mannitol at the time of bone flap removal to relax the brain if anesthesia agrees that the blood pressure will tolerate diuresis. 
	NOTE: This will allow time for the diuresis to occur and ultimately will relax the brain to help maximize gravity dependent brain retraction during dissection.</li>
	<li>Keep End-Tidal pCO2 between 30-35 mm Hg to achieve slight hypercapnea. NOTE: This will safely allow for brain relaxation and maximize gravity dependent brain retraction during dissection.</li>
	<li>Evacuate cerebrospinal fluid (CSF) to promote brain relaxation by opening the arachnoid cisterns in the interoptic, carotid-optic, and carotid-oculomotor cisterns and patiently suction CSF until the desired brain relaxation has been achieved. 
	NOTE: This typically takes about 1 min; no lumbar drain is needed with this technique and it dramatically opens the surgical corridors.</li>
</ol>
3. Sylvian Fissure Dissection
<ol>
	<li>Bring the intra-operative microscope with the mouthpiece into the field using sterile techniques. Also bring surgical chairs with arm support into the field sterilely to maximize bimanual dexterity and to prevent surgeon arm and hand fatigue. 
	NOTE: The mouthpiece should be adjusted before draping so that the surgeon can move the microscope with the mouth while simultaneously looking through the ocular pieces.</li>
	<li>Perform dissection. 
	NOTE: For anterior communicating artery aneurysms, no Sylvian Fissure dissection is required and minimal (2-3 mm in extreme cases only, but this is a rare occurrence) to no gyrus rectus resection is needed using only subfrontal dissection; all other supraclinoid anterior circulation aneurysm locations (including posterior communicating artery) require &#60;1 cm proximal Sylivan Fissure dissection to expose the supraclinoid internal carotid artery, its branches (posterior communicating and anterior choroidal arteries), the internal carotid artery terminus, the A1 and M1 origins, and the proximal A2 and M2 segments distal to their respective bifurcations. Total Sylvian Fissure exposure was dime-size (1 cm x 1 cm) and no brain retractors were used for any of the cases reported. Gravity dependent brain relaxation was sufficient for excellent exposure of the soft tissue structures and vasculature needed to perform surgical clip ligation in the areas discussed above.</li>
	<li>Using bimanual manipulation with surgical microinstruments gently open the arachnoid corridors, holding the brain tissue aside with the edge of the instrument handles or suction device as needed through this exposure. 
	NOTE: The senior author&#39;s preference is to use a 4-French Fukishima suction tip in the non-dominant hand and in the dominant hand bipolar bayonettes for blunt dissection or microscissors for sharp dissection. Moistened Telfa strips are placed on the brain surface at the site of manipulation to prevent cortical injury. Cottonoids often stick to the brain surface and can&#8217;t be easily advanced deeper as the dissection progresses, without causing mild cortical injury.</li>
	<li>Use the mouthpiece on the operating microscope frequently to adjust the scope and focus length as needed while keeping both hands in the field.</li>
	<li>Secure the aneurysm in standard fashion, using the suction most often in the non-dominant hand to maintain the surgical corridor and visualization free of CSF.</li>
	<li>After clip placement, perform intra-operative Doppler of the aneurysm dome to confirm cessation of flow as well as the inflow and outflow vessels to confirm flow and carefully examine the aneurysm neck and parent vessels. We reserve intra-operative digital subtraction angiography (DSA) for anterior communicating artery aneurysms and those clipped aneurysms where inflow, outflow, or aneurysm neck cannot be visualized completely or there is a concern with intra-operative Doppler. Intra-operative DSA is preferred over indocyanine green (ICG) angiography because when multiple aneurysm clips are used to reconstruct the aneurysm neck, the clip can obstruct visualization. NOTE: Once the aneurysm has been securely clipped, the microscope is removed from the field and the brain irrigated with normal saline solution to minimize the amount of pneumocephalus after closure.</li>
	<li>After inspecting the clip for aneurysm occlusion with the Doppler, the aneurysm dome is perforated with a 22 G needle attached to intravenous tubing and a 10 ml syringe and manually suction aspirated to confirm aneurysm occlusion.</li>
	<li>Reapproximate the native dura with 4-0 surgilon and cover with a synthetic dural substitute if a watertight closure is not able to be obtained properly.</li>
	<li>Secure bone plates with a metal plating system per standard of care.</li>
	<li>Secure the frontal edge of the bone flap flush against the native bone to avoid space between the two which would not be cosmetically pleasing after the tissues heal.</li>
	<li>Reapproximate the temporalis muscle fascia with interrupted 2-0 Vicryl sutures. Secure the top of the temporalis muscle with a 2-0 Vicryl stitch to the frontal metal plate to reapproximate it to the superior temporal line.</li>
	<li>Reapproximate the galea using 3-0 Vicryl sutures and close the scalp in a standard fashion using either staples, nylon, or prolene. Dress with sterile bandages per surgeon preference.</li>
</ol>
4. Post-treatment Care
<ol>
	<li>Admit patient to the intensive care unit after treatment and mobilize with the nursing staff as soon as sedation or general anesthesia has worn off enough to do so, typically within 6 hr of extubation.</li>
	<li>Order physical and occupational therapy to begin post-operative day one in order to assess the patient for safe discharge to home if there were any concerns by the nursing staff.</li>
	<li>Discharge the patient when criteria are met: pain controlled with only oral medications, voiding independently, ambulating independently, and tolerating oral food intake.</li>
</ol>

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Eric Deshaies is a physician consultant for MicroVention, Covidien Neurovascular, Integra LifeSciences Corporation.

Surgical clip ligation of intracranial aneurysms remains a relevant and important option in treating certain types of aneurysms, though this role has been diminishing over the past several years as endovascular technology becomes safer and more efficacious. Endovascular treatment has surpassed surgery for cerebral aneurysms, yet the higher recurrence rate after endovascular treatment, the occasional need for surgical treatment after aneurysm recurrence from failed endovascular treatment, specific morphologies making endo...

Surgical clip ligation had been the mainstay of treatment for intracranial aneurysms but has been recently supplanted mostly by less invasive endovascular techniques.1,2 Clinical trials including the International Study of Unruptured Intracranial Aneurysms (ISUIA-1 and ISUIA-2), and the International Subarachnoid Aneurysm Trial (ISAT) have demonstrated lower morbidity and mortality, reduced length of hospital stay, and lower overall expense, with endovascular treatment compared to surgical clip ligation.3&#8211;5 However, the higher aneurysm recurrence rate after endovascular therapy has led to the examination of the cumulative risk to the patients compared to surgical clip ligation.3,4 Surgical treatment remains an important modality for aneurysm therapy, particularly for anterior circulation aneurysms that have morphologies that may be difficult to treat with endovascular means.
Unlike advancements in endovascular devices, few advances in surgical techniques have been made recently. Techniques to make surgical treatment less invasive have included the supraorbital craniotomy combined with the eyebrow incision for anterior circulation aneurysms and &#8220;retractorless surgery&#8221; to minimize surgical trauma to the brain during aneurysm clipping.6&#8211;8 These less invasive surgical approaches may reduce length of hospital stay, surgical morbidity, treatment cost, and improve patient outcomes.9
Here, we present our experience with a minimally invasive approach to surgical clip ligation of unruptured intracranial aneurysms using a pterional approach for anterior circulation aneurysms performed in a major tertiary cerebrovascular center and compare the results with an age matched dataset from the Nationwide Inpatient Sample (NIS). The surgical technique will be reviewed, including patient preparation, brain relaxation, sylvian fissure dissection, and closure. Post-operative care and discharge requirements will also be outlined.

<table><tbody><tr><td>Mayfield Infinity skull clamp</td><td>Integra</td><td>A-1114</td><td></td></tr><tr><td>Mayfield table attachment</td><td>Integra</td><td>A-1018</td><td></td></tr><tr><td>4-French Fukishima suction tip</td><td>Integra</td><td>R-8986</td><td></td></tr><tr><td>Periosteal elevator (Langenbeck)</td><td>Codman</td><td>65-1116</td><td></td></tr><tr><td>Metzenbaum scissors</td><td>Codman</td><td>36-5023</td><td></td></tr><tr><td>Malis dissector, round angled</td><td>Codman</td><td>80-1541&amp;nbsp;</td><td></td></tr><tr><td>Penfield dissector, style 1</td><td>Codman</td><td>65-1015</td><td></td></tr><tr><td>Lempert bone rongeur</td><td>Codman</td><td>19-1232</td><td></td></tr><tr><td>Malis Irrigation Module</td><td>Codman</td><td>Module 1000</td><td></td></tr><tr><td>Bovie monopolar electrocautery device</td><td>Codman</td><td></td><td></td></tr><tr><td>Insulated blade for electrocautery device</td><td>Covidien</td><td>E1455</td><td></td></tr><tr><td>Fish-hook retractors</td><td>Lone Star</td><td>3350-8G</td><td></td></tr><tr><td>Pneumatic drill</td><td>Medtronic</td><td>Midas Rex MR7</td><td></td></tr><tr><td>Side-cutting drill</td><td>Medtronic</td><td>F2/8TA23</td><td></td></tr><tr><td>Fluted legend match head tool</td><td>Medtronic</td><td>10MH30</td><td></td></tr><tr><td>Surgical scalpel No. 10, 11, 15</td><td>Bard-Parker</td><td>0029064 (No.10), 0018291 (No.11), 0018043 (No.15)</td><td></td></tr><tr><td>Intra-operative microscope with mouthpiece</td><td>Leica</td><td></td><td></td></tr><tr><td>Microscissors</td><td>V. Mueller</td><td>NL3785-034(st), NL3785-035(cvd)</td><td></td></tr><tr><td>Rhoton dissector, #2</td><td>V. Mueller</td><td>NL3785-002&amp;nbsp;</td><td></td></tr><tr><td>Telfa strips</td><td>American Surgical</td><td>#80-09 (1/2x3), #80-04 (1/4x3)</td><td></td></tr><tr><td>Aneurysm clip</td><td>Aesculap</td><td></td><td></td></tr><tr><td>Raney clip applier</td><td>Aesculap</td><td>FF012R</td><td></td></tr><tr><td>Synthes Matrix metal plating system</td><td>Synthes</td><td></td><td></td></tr><tr><td>Braided absorbable surgical sutures (Vicyrl)&amp;nbsp;</td><td>Ethicon</td><td>J790D (3-0), J743D (4-0)</td><td></td></tr><tr><td>Braided nylon nonabsorbable surgical sutures (Nurolon) 4-0</td><td>Ethicon</td><td>C584D</td><td></td></tr><tr><td>Doppler System</td><td>Mizuho</td><td>07-150-02</td><td></td></tr></tbody></table>

minimally invasive thumb-sized pterional craniotomy for surgical clip ligation of unruptured anterior circulation aneurysms

Less invasive surgical approaches for intracranial aneurysm clipping may reduce length of hospital stay, surgical morbidity, treatment cost, and improve patient outcomes. We present our experience with a minimally invasive pterional approach for anterior circulation aneurysms performed in a major tertiary cerebrovascular center and compare the results with an aged matched dataset from the Nationwide Inpatient Sample (NIS). From August 2008 to December 2012, 22 elective aneurysm clippings on patients &#8804;55 years of age were performed by the same dual fellowship-trained cerebrovascular/endovascular neurosurgeon. One patient (4.5%) experienced transient post-operative complications. 18 of 22 patients returned for follow-up imaging and there were no recurrences through an average duration of 22 months. A search in the NIS database from 2008 to 2010, also for patients aged &#8804;55 years of age, yielded 1,341 hospitalizations for surgical clip ligation of unruptured cerebral aneurysms. Inpatient length of stay and hospital charges at our institution using the minimally invasive thumb-sized pterional technique were nearly half that of NIS (length of stay: 3.2 vs 5.7 days; hospital charges: $52,779 vs. $101,882). The minimally invasive thumb-sized pterional craniotomy allows good exposure of unruptured small and medium-sized supraclinoid anterior circulation aneurysms. Cerebrospinal fluid drainage from key subarachnoid cisterns and constant bimanual microsurgical techniques avoid the need for retractors which can cause contusions, localized venous infarctions, and post-operative cerebral edema at the retractor sites. Utilizing this set of techniques has afforded our patients with a shorter hospital stay at a lower cost compared to the national average.

Currently, at our institution over 150 aneurysms are treated annually. From August 2008 to December 2012, 22 elective aneurysm clippings using this minimally invasive thumb-sized pterional craniotomy technique for supraclinoidal aneurysms on patient&#8217;s &#8804;55 years of age were performed by the same dual fellowship-trained cerebrovascular/endovascular neurosurgeon that developed this technique (EMD) (Table 1). This age group was chosen as earlier trials have shown that surgical treatment of aneury...

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Minimally Invasive Thumb-sized Pterional Craniotomy for Surgical Clip Ligation of Unruptured Anterior Circulation Aneurysms

Minimally invasive thumb-sized pterional craniotomy for aneurysm clipping has afforded our patients with a shorter hospital stay at a lower cost compared to the national average.

Less invasive surgical approaches for intracranial aneurysm clipping may reduce length of hospital stay, surgical morbidity, treatment cost, and improve ...

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Research

JoVE Journal

Medicine

15.4K Views.  Crouse Neuroscience Institute. Minimally invasive thumb-sized pterional craniotomy for aneurysm clipping has afforded our patients with a shorter hospital stay at a lower cost compared to the national average.

Video: Minimally Invasive Thumb-sized Pterional Craniotomy for Surgical Clip Ligation of Unruptured Anterior Circulation Aneurysms

Microvascular Decompression: Salient Surgical Principles and Technical Nuances

Trigeminal neuralgia is a disorder associated with severe episodes of lancinating pain in the distribution of the trigeminal nerve. Previous reports indicate that 80-90% of cases are related to compression of the trigeminal nerve by an adjacent vessel. The majority of patients with trigeminal neuralgia eventually require surgical management in order to achieve remission of symptoms. Surgical options for management include ablative procedures (e.g., radiosurgery, percutaneous radiofrequency lesioning, balloon compression, glycerol rhizolysis, etc.) and microvascular decompression. Ablative procedures fail to address the root cause of the disorder and are less effective at preventing recurrence of symptoms over the long term than microvascular decompression. However, microvascular decompression is inherently more invasive than ablative procedures and is associated with increased surgical risks. Previous studies have demonstrated a correlation between surgeon experience and patient outcome in microvascular decompression. In this series of 59 patients operated on by two neurosurgeons (JSN and PEK) since 2006, 93% of patients demonstrated substantial improvement in their trigeminal neuralgia following the procedure&#x2014;with follow-up ranging from 6 weeks to 2 years. Moreover, 41 of 66 patients (approximately 64%) have been entirely pain-free following the operation.
In this publication, video format is utilized to review the microsurgical pathology of this disorder. Steps of the operative procedure are reviewed and salient principles and technical nuances useful in minimizing complications and maximizing efficacy are discussed.

There are many available options for management of the patient with trigeminal neuralgia. Microvascular decompression, while the most invasive of all options, is also the most effective at achieving long term remission of symptoms. Video instruction on how to maximize efficacy and minimize complications with this procedure is described.

Trigeminal neuralgia is a disorder associated with severe episodes of lancinating pain in the distribution of the trigeminal nerve. Previous reports ...

Permanent Cerebral Vessel Occlusion via Double Ligature and Transection

Stroke is a leading cause of death, disability, and socioeconomic loss worldwide. The majority of all strokes result from an interruption in blood flow (ischemia) 1. Middle cerebral artery (MCA) delivers a great majority of blood to the lateral surface of the cortex 2, is the most common site of human stroke 3, and ischemia within its territory can result in extensive dysfunction or death 1,4,5. Survivors of ischemic stroke often suffer loss or disruption of motor capabilities, sensory deficits, and infarct. In an effort to capture these key characteristics of stroke, and thereby develop effective treatment, a great deal of emphasis is placed upon animal models of ischemia in MCA.
Here we present a method of permanently occluding a cortical surface blood vessel. We will present this method using an example of a relevant vessel occlusion that models the most common type, location, and outcome of human stroke, permanent middle cerebral artery occlusion (pMCAO). In this model, we surgically expose MCA in the adult rat and subsequently occlude via double ligature and transection of the vessel. This pMCAO blocks the proximal cortical branch of MCA, causing ischemia in all of MCA cortical territory, a large portion of the cortex. This method of occlusion can also be used to occlude more distal portions of cortical vessels in order to achieve more focal ischemia targeting a smaller region of cortex. The primary disadvantages of pMCAO are that the surgical procedure is somewhat invasive as a small craniotomy is required to access MCA, though this results in minimal tissue damage. The primary advantages of this model, however, are: the site of occlusion is well defined, the degree of blood flow reduction is consistent, functional and neurological impairment occurs rapidly, infarct size is consistent, and the high rate of survival allows for long-term chronic assessment.

Permanent Cerebral Vessel Occlusion via Double Ligature and Transection

We describe a highly reproducible method for the permanent occlusion of a rodent major cerebral blood vessel. This technique can be accomplished with very little peripheral damage, minimal blood loss, a high rate of long-term survival, and consistent infarct volume commensurate with the human clinical population.

Stroke is a leading cause of death, disability, and socioeconomic loss worldwide. The majority of all strokes result from an interruption in blood flow ...

Microsurgical Clip Obliteration of Middle Cerebral Aneurysm Using Intraoperative Flow Assessment

Cerebral aneurysms are abnormal widening or ballooning of a localized segment of an intracranial blood vessel.  Surgical clipping is an important treatment for aneurysms which attempts to exclude blood from flowing into the aneurysmal segment of the vessel while preserving blood flow in a normal fashion.  Improper clip placement may result in residual aneurysm with the potential for subsequent aneurysm rupture or partial or full occlusion of distal arteries resulting in cerebral infarction.  Here we describe the use of an ultrasonic flow probe to provide quantitative evaluation of arterial flow before and after microsurgical clip placement at the base of a middle cerebral artery aneurysm.  This information helps ensure adequate aneurysm reconstruction with preservation of normal distal blood flow.

Description of the surgical obliteration of a cerebral aneurysm utilizing an ultrasonic flow probe to assess arterial flow prior to and after aneurysm clip placement.

Cerebral aneurysms are abnormal widening or ballooning of a localized segment of an intracranial blood vessel.  Surgical clipping is an important ...

Biology

A Large Lateral Craniotomy Procedure for Mesoscale Wide-field Optical Imaging of Brain Activity

The craniotomy is a commonly performed procedure to expose the brain for in vivo experiments. In mouse research, most labs utilize a small craniotomy, typically 3 mm x 3 mm. This protocol introduces a method for creating a substantially larger 7 mm x 6 mm cranial window exposing most of a cerebral hemisphere over the mouse temporal and parietal cortices (e.g., bregma 2.5 - 4.5 mm, lateral 0 - 6 mm). To perform this surgery, the head must be tilted approximately 30&#176; and much of the temporal muscle must be retracted. Due to the large amount of bone removal, this procedure is intended only for acute experiments with the animal anesthetized throughout the surgery and experiment.
The main advantage of this innovative large lateral cranial window is to provide simultaneous access to both medial and lateral areas of the cortex. This large unilateral cranial window can be used to study the neural dynamics between cells, as well as between different cortical areas by combining multi-electrode electrophysiological recordings, imaging of neuronal activity (e.g., intrinsic or extrinsic imaging), and optogenetic stimulation. Additionally, this large craniotomy also exposes a large area of cortical blood vessels, allowing for direct manipulation of the lateral cortical vasculature.

This protocol presents a method for creating a large unilateral craniotomy over the temporal and parietal regions of the mouse cerebral cortex. This is especially useful for real time imaging over an expansive area of a cortical hemisphere.

The craniotomy is a commonly performed procedure to expose the brain for in vivo experiments. In mouse research, most labs utilize a small craniotomy, ...

Neuroscience

Lateral Chronic Cranial Window Preparation Enables In Vivo Observation Following Distal Middle Cerebral Artery Occlusion in Mice

Focal cerebral ischemia (i.e., ischemic stroke) may cause major brain injury, leading to a severe loss of neuronal function and consequently to a host of motor and cognitive disabilities. Its high prevalence poses a serious health burden, as stroke is among the principal causes of long-term disability and death worldwide1. Recovery of neuronal function is, in most cases, only partial. So far, treatment options are very limited, in particular due to the narrow time window for thrombolysis2,3. Determining methods to accelerate recovery from stroke remains a prime medical goal; however, this has been hampered by insufficient mechanistic insights into the recovery process. Experimental stroke researchers frequently employ rodent models of focal cerebral ischemia. Beyond the acute phase, stroke research is increasingly focused on the sub-acute and chronic phase following cerebral ischemia. Most stroke researchers apply permanent or transient occlusion of the MCA in mice or rats. In patients, occlusions of the MCA are among the most frequent causes of ischemic stroke4. Besides proximal occlusion of the MCA using the filament model, surgical occlusion of the distal MCA is probably the most frequently used model in experimental stroke research5. Occlusion of a distal (to the branching of the lenticulo-striate arteries) MCA branch typically spares the striatum and primarily affects the neocortex. Vessel occlusion can be permanent or transient. High reproducibility of lesion volume and very low mortality rates with respect to the long-term outcome are the main advantages of this model. Here, we demonstrate how to perform a chronic cranial window (CW) preparation lateral to the sagittal sinus, and afterwards how to surgically induce a distal stroke underneath the window using a craniotomy approach. This approach can be applied for sequential imaging of acute and chronic changes following ischemia via epi-illuminating, confocal laser scanning, and two-photon intravital microscopy.

Lateral Chronic Cranial Window Preparation Enables In Vivo Observation Following Distal Middle Cerebral Artery Occlusion in Mice

Surgical occlusion of a distal middle cerebral artery branch (MCAo) is a frequently used model in experimental stroke research. This manuscript describes the basic technique of permanent MCAo, combined with the insertion of a lateral cranial window, which offers the opportunity for longitudinal intravital microscopy in mice.

Focal cerebral ischemia (i.e., ischemic stroke) may cause major brain injury, leading to a severe loss of neuronal function and consequently to a host of ...

Comprehensive Endovascular and Open Surgical Management of Cerebral Arteriovenous Malformations

Arteriovenious malformations (AVMs) are associated with significant morbidity and mortality, and have a rupture risk of ~3% per year. Treatment of AVMs must be tailored specifically to the lesion, with surgical resection being the gold standard for small, accessible lesions. Pre-operative embolization of AVMs can reduce nidal blood flow and remove high-risk AVM features such as intranidal or venous aneurysms, thereby simplifying a challenging neurosurgical procedure. Herein, we describe our approach for the staged endovascular embolization and open resection of AVMs, and highlight the advantages of having a comprehensively trained neurovascular surgeon leading a multi-disciplinary clinical team. This includes planning the craniotomy and resection to immediately follow the final embolization stage, thereby using a single session of anesthesia for aggressive embolization, and rapid resection. Finally, we provide a representative case of a 22-year-old female with an unruptured right frontal AVM diagnosed during a seizure workup, who was successfully treated via staged embolizations followed by open surgical resection.

Surgery is the gold standard for accessible arteriovenious malformations (AVMs), and pre-operative embolization can simplify this procedure. We describe our approach for staged endovascular embolization and open resection of AVMs, and provide a representative clinical example highlighting the advantages of a comprehensively trained neurovascular surgeon leading a multi-disciplinary clinical team.

Arteriovenious malformations (AVMs) are associated with significant morbidity and mortality, and have a rupture risk of ~3% per year. Treatment of AVMs ...

Development of a Cadaveric Multiport Model of Posterior Circulation Aneurysm Clipping for Neurosurgery and Otolaryngology Residents

Posterior circulation aneurysms are difficult to treat with the current methods of coiling and clipping. To address limitations in training, we developed a cadaveric model to train learners on endoscopic clipping of posterior circulation aneurysms. An endoscopic transclival approach (ETA) and a transorbital precaruncular approach (TOPA) to successfully access and clip aneurysms of the posterior circulation are described. The model has flexibility in that a colored silicone compound can be injected into the cadaveric vessels for the purpose of training learners on vascular anatomy. The other option is that the model could be connected to a vascular perfusion pump allowing real-time appreciation of a pulsatile or ruptured aneurysm. This cadaveric model is the first of its kind for training of endoscopic clipping of posterior circulation aneurysms. Learners will develop proficiency in endoscopic skills, appropriate dissection, and appreciation for relative anatomy while developing an algorithm that can be employed in a real operative arena. Going forward, various clinical scenarios can be developed to enhance the realism, allow learners from different specialties to work together, and emphasize the importance of teamwork and effective communication.

A model protocol to train neurosurgery and otolaryngology resident learners on endoscopic transclival clipping of posterior circulation aneurysms is described. Two endoscopic approaches to access the silicone-injected or perfused posterior circulation of cadaveric heads are established for training. Learners are tasked with clipping of posterior circulation based on clinical scenarios.

Posterior circulation aneurysms are difficult to treat with the current methods of coiling and clipping. To address limitations in training, we developed ...

Creation of Two Saccular Elastase-Digested Aneurysms with Different Hemodynamics in One Rabbit

Preclinical animal models with hemodynamic, morphologic, and histologic characteristics close to human intracranial aneurysms play a key role in the understanding of the pathophysiological processes and the development and testing of new therapeutic strategies. This study aims to describe a new rabbit aneurysm model that allows the creation of two elastase-digested saccular aneurysms with different hemodynamic conditions within the same animal.
Five female New Zealand white rabbits with a mean weight of 4.0 (&#177; 0.3) kg and mean age of 25 (&#177;5) weeks underwent microsurgical stump and bifurcation aneurysm creation. One aneurysm (stump) was created by right common carotid artery (CCA) exposure at its origin at the brachiocephalic trunk. A temporary clip was applied at the CCA origin and another, 2 cm above. This segment was treated with a local injection of 100 U of elastase for 20 min. A second aneurysm (bifurcation) was created by suturing an elastase-treated arterial pouch into the end-to-side anastomosis of the right CCA to left CCA. Patency was controlled by fluorescence angiography immediately after creation.
The average duration of surgery was 221 min. The creation of two aneurysms in the same animal was successful in all rabbits without complication. All aneurysms were patent immediately after surgery except for one bifurcation aneurysm, which showed an extreme tissue reaction due to elastase incubation and an immediate intraluminal thrombosis. No mortality was observed during surgery and up to one-month follow-up. Morbidity was limited to a transient vestibular syndrome (one rabbit), which recovered spontaneously within one day.
Demonstrated here for the first time is the feasibility of creating a two-aneurysm rabbit model with stump and bifurcation hemodynamic characteristics and highly degenerated wall conditions. This model allows the study of the natural course and potential treatment strategies on the basis of aneurysm biology under different flow conditions.

This protocol describes the steps for the creation of a rabbit model with two elastase-digested aneurysms with different hemodynamics (stump and bifurcation constellation). This allows the testing of novel endovascular devices in aneurysms with different angioarchitecture and hemodynamic conditions within a single animal.

Preclinical animal models with hemodynamic, morphologic, and histologic characteristics close to human intracranial aneurysms play a key role in the ...

Optimization of the Longa Middle Cerebral Artery Occlusion Method for Complete Reperfusion

The middle cerebral artery occlusion model serves as the primary animal model for studying ischemic stroke. Despite being used in research for over three decades, its standardization remains inadequate. Predominantly conducted on rats and mice, the procedure poses challenges due to mice's smaller and more fragile nature. Unlike the Koizumi common carotid artery method, the Longa external carotid artery is the sole intraluminal filament stroke model ensuring complete reperfusion post-ischemia. This aspect holds critical significance for studies investigating reperfusion phenomena. The surgical modifications demonstrated in this article ensure continuous blood flow from the common carotid artery throughout the ischemic phase and after the reperfusion onset. The goal of these modifications is to selectively occlude the middle cerebral artery by keeping the perfusion uninterrupted in branches proximal to the middle cerebral artery during the ischemia period. Furthermore, the onset of reperfusion is sudden and can be precisely controlled, thereby modeling endovascular thrombectomy in human medicine more accurately. Our aim in presenting this comprehensive video article is to ease the training of new surgeons and promote the standardization of surgical procedures within the scientific community.

This protocol presents a step-by-step guide for researchers to perform the middle cerebral artery occlusion procedure on mice using the modified Longa external carotid artery method. Modifications presented in this article aim to increase the accuracy of middle cerebral artery occlusion and ensure complete reperfusion.

The middle cerebral artery occlusion model serves as the primary animal model for studying ischemic stroke. Despite being used in research for over three ...

Improving Outcomes in Anteromesial Temporal Lobe Resections - A Demonstration of Resecting the Temporal Piriform Cortex

Anteromesial temporal lobe resection (ATLR) is a useful treatment option for drug-resistant mesial temporal lobe epilepsy (DRmTLE). Growing evidence suggests the piriform cortex plays a crucial role in the generation and propagation of seizures in DRmTLE - and that the resection of the temporal portion of the piriform cortex is associated with significantly improved rates of seizure freedom. 
Here, we present the resection of the temporal portion of the piriform cortex in ATLR, using high-resolution preoperative probabilistic tractography algorithms and fused anatomical masks of the structures of interest into the intraoperative neuronavigation and microscope head-up display (HUD). 
All patients undergoing comprehensive preoperative assessment and investigations for DRmTLE provided informed, written consent to record an intraoperative video of the procedure. Patients were identified by an expert multidisciplinary team of epileptologists, epilepsy neurosurgeons, neuropsychologists, neuropsychiatrists, and electrophysiologists at a large epilepsy surgery center. The preoperative imaging pipeline included the delineation of critical structures. This included the temporal piriform cortex, and high-resolution probabilistic tractography for essential tracts at risk (e.g., optic radiation and inferior fronto-occipital fasciculus). These were co-registered to the preoperative volumetric neuronavigation scan and uploaded to the intra-operative neuronavigation system. 
Presented here is a step-by-step procedure of ATLR, including the resection of the temporal portion of the piriform cortex. The protocol combines Advanced structural and diffusion MR imaging and intraoperative visual aids to integrate anatomical masks of critical grey matter structures and white matter tracts into the surgical workflow in the operating room.

Here, we demonstrate an approach to intraoperative neurosurgical guidance in anteromesial temporal lobe resections, specifically highlighting the use of tractography and anatomical masks to aid safe resection of the temporal portion of the piriform cortex - an area increasingly regarded as a crucial surgical target in drug-resistant mesial temporal lobe epilepsy.

Anteromesial temporal lobe resection (ATLR) is a useful treatment option for drug-resistant mesial temporal lobe epilepsy (DRmTLE). Growing evidence ...

Minimally Invasive Thumb-sized Pterional Craniotomy for Surgical Clip Ligation of Unruptured Anterior Circulation Aneurysms

Summary

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Chapters in this video

Microvascular Decompression: Salient Surgical Principles and Technical Nuances

Permanent Cerebral Vessel Occlusion via Double Ligature and Transection

Microsurgical Clip Obliteration of Middle Cerebral Aneurysm Using Intraoperative Flow Assessment

A Large Lateral Craniotomy Procedure for Mesoscale Wide-field Optical Imaging of Brain Activity

Lateral Chronic Cranial Window Preparation Enables In Vivo Observation Following Distal Middle Cerebral Artery Occlusion in Mice

Comprehensive Endovascular and Open Surgical Management of Cerebral Arteriovenous Malformations

Development of a Cadaveric Multiport Model of Posterior Circulation Aneurysm Clipping for Neurosurgery and Otolaryngology Residents

Creation of Two Saccular Elastase-Digested Aneurysms with Different Hemodynamics in One Rabbit

Optimization of the Longa Middle Cerebral Artery Occlusion Method for Complete Reperfusion

Improving Outcomes in Anteromesial Temporal Lobe Resections - A Demonstration of Resecting the Temporal Piriform Cortex