Morphological features of the greater occipital nerve and its possible importance for interventional procedures.

Being one of the most prevalent neurological symptoms, headaches are burdensome and costly. Blocks and decompression surgeries of the greater occipital nerve (GON) have been frequently used for migraine, cervicogenic headache, and occipital neuralgia which are classified under headache by International Headache Society. Knowledge of complex anatomy of GON is crucial for its decompression surgery and block. This study was performed to elucidate anatomical features of this nerve in detail. Forty-one cadavers were dissected bilaterally. According to its morphological features, GON was classified into four main types that included 18 subtypes. Moreover, potential compression points of the nerve were defined. The number of branches of the GON up to semispinalis capitis muscle and the number of its branches that were sent to this muscle were recorded. The most common variant was that the GON pierced the aponeurosis of the trapezius muscle, curved around the lower edge of the obliquus capitis inferior muscle, and was loosely attached to the obliquus capitis inferior muscle (Type 2; 61 sides, 74.4%). In the subtypes, the most common form was Type 2-A (44 sides, 53.6%), in which the GON pierced the aponeurosis of each of the trapezius muscle and fibers of semispinalis muscle at one point and there was a single crossing of the GON and occipital artery. Six potential compression points of the GON were detected. The first point was where the nerve crossed the lower border of the obliquus capitis inferior muscle. The second and third points were at its piercing of the semispinalis capitis muscle and the muscle fibers/aponeurosis of the trapezius, respectively. Fourth, fifth, and sixth compression points of GON were located where the GON and occipital artery crossed each other for the first, second, and third times, respectively. On 69 sides, 1-4 branches of the GON up to the semispinalis capitis muscle were observed (median = 1), while 1-4 branches of GON were sent to the semispinalis capitis muscle on 67 sides (median = 1). The novel anatomical findings described in this study may play a significant role in increasing the success rate of invasive interventions related with the GON.

Occipital artery to vertebral artery bypass for treatment of bilateral vertebral artery occlusion with QMRA as an adjunct to diagnostic assessment.

PURPOSE: Stroke, the second leading cause of death globally, often involves ischemia in the vertebrobasilar territory. This condition is underexplored, despite significant morbidity and mortality risks. The purpose of this study is to present a case of occipital artery to V3 segment vertebral artery bypass, emphasizing the role of quantitative magnetic resonance angiography (qMRA) in assessing flow and guiding surgical intervention. METHODS: A 66-year-old man with bilateral vertebral artery occlusion presented acute symptoms. qMRA was employed to evaluate flow dynamics and determine the feasibility of a flow augmentation bypass surgery. The occipital artery to left vertebral artery bypass (OA-to-VA) was performed, utilizing an inverted hockey-stick incision and an antegrade inside-out technique. The patency of the bypass was confirmed using both Doppler probe and Indocyanine green. RESULTS: Postoperative assessments, including computed tomography angiography (CTA) and qMRA, demonstrated the patency of the bypass with improved flow in the basilar artery and left vertebral artery. The patient's condition remained stable postoperatively, with residual peripheral palsy of the left facial nerve. CONCLUSION: In conclusion, the presented case illustrates the efficacy of the OA-to-VA bypass in addressing symptomatic bilateral vertebral artery occlusion. The study underscores the pivotal role of qMRA in pre- and postoperative assessments, providing noninvasive flow quantification for diagnostic considerations and long-term follow-up in patients with vertebrobasilar insufficiency.

A scarce combination of arterial variants: an occipital artery originating from the internal carotid artery associated with a linguofacial trunk.

The occipital artery (OA) typically originates from the external carotid artery (ECA). Variations of the ECA has been well described in the current literature, while the OA is a relatively stable vessel, and its variations are uncommon. In the current case report, an aberrant OA has been found coexisting with a linguofacial trunk (LFT) on the right hemineck of a 51-year-old male patient. The OA was identified originating from the cervical internal carotid artery (ICA) at the level of the second cervical vertebra (C2). On the ECA, the lingual and facial arteries were emanating in common, as LFT. The left hemineck of the patient was free of variations. The current coexistence of arterial variants has been reported only once previously; therefore, the current case corresponds to the second case in the English literature. The aberrant OA origin from the ICA has been estimated with a pooled prevalence of 0.37%, while the origin at the C2 level and from the anterior surface of the ICA corresponds to a very rare variation. Additionally, the LFT is one of the most common trunk that can be found on the ECA. Interventional radiologists and surgeons must be aware of common and uncommon variation to avoid iatrogenic lesion.

An anatomical study of the sigmoid sinus artery: Application to the transmastoid approach.

INTRODUCTION: We aimed to investigate the morphological features of the artery that traverse the sigmoid sinus's lateral surface and to discuss this structure's clinical relevance. METHODS: Ten sides from five cadaveric Caucasian heads were used for gross anatomical dissection to investigate the morphological features of the sigmoid sinus artery (SSA), and additional five sides were used for histological observation. RESULTS: The SSA was found on eight out of ten sides (80%). The mean diameter of the SSA was 0.3 mm. The mean distance from the tip of the mastoid process to the artery was 20.3 mm. Histological observation identified extradural and intradural courses of SSA. The intradural course was further categorized into protruding and non-protruding types. In the protruding type, the SSA traveled within the dura but indented into the bone, making it more or less an intraosseous artery. In the non-protruding type, the SSA traveled within the dura but did not protrude into the bone but rather indented into the lumen of the SS. In all sections, both intradural and extradural courses were identified simultaneously. CONCLUSIONS: When the mastoid foramen is observed, it does not always only carry an emissary vein but also an artery. The SSA could be considered a "warning landmark" during bone drilling for the transmastoid approach.

Risk of postoperative scalp necrosis in the occipital artery region after posterior cranial fossa surgery.

Ischemia-induced postoperative scalp necrosis in the superficial temporal artery (STA) region is known to occur after STA-middle cerebral artery anastomoses. However, no reports have evaluated the risk of postoperative scalp necrosis in the occipital artery (OA) region. This study examined the surgical procedures that pose a risk for postoperative scalp necrosis in the OA region following posterior cranial fossa surgery. Patients who underwent initial posterior fossa craniotomy at our institution from 2015 to 2022 were included. Clinical information was collected using medical records. Regarding surgical procedures, we evaluated the incision design and whether a supramuscular scalp flap was prepared. The supramuscular scalp flap was defined as a scalp flap dissected from the sternocleidomastoid and/or splenius capitis muscles. A total of 392 patients were included. Postoperative scalp necrosis occurred in 19 patients (4.8%). There were 296 patients with supramuscular scalp flaps, and supramuscular scalp flaps prepared in all 19 patients with postoperative necrosis. Comparing incision designs among patients with supramuscular scalp flap, a hockey stick-shaped scalp incision caused postoperative necrosis in 14 of 73 patients (19.1%), and the odds of postoperative scalp necrosis were higher with the hockey stick shape than with the retro-auricular C shape (adjusted odds ratio: 12.2, 95% confidence interval: 3.86-38.3, p = 0.00002). In all the cases, ischemia was considered to be the cause of postoperative necrosis. The incidence of postoperative necrosis is particularly high when a hockey stick-shaped scalp incision is combined with a supramuscular scalp flap.

Occipital artery-to-PICA bypass: how I do it.

BACKGROUND: Posterior inferior cerebellar artery (PICA) aneurysms are uncommon, and their management is challenging because of the complex angioarchitecture of the PICA and the frequently nonsaccular aneurysm presentation. Endovascular therapy may not be feasible. METHODS: We describe our technique of clip trapping with occipital artery (OA)-to-PICA bypass to treat a PICA aneurysm. Because the aneurysm affected the ipsilateral, dominant PICA, an OA-PICA bypass was chosen to ensure adequate flow and reduce risk to the contralateral PICA supply. CONCLUSION: The OA-PICA anastomosis is a safe and effective method to successfully achieve flow preservation with bypass reconstruction and aneurysm trapping.

Internal carotid artery anatomy - not always straightforward.

OBJECTIVES: To present a rare variant of internal carotid artery anatomy. METHODS: Case report presenting CT angiography finding of internal carotid anatomy variant. RESULTS: We present the case of an unusual origin of the occipital artery from cervical portion of the internal carotid artery as an incidental finding during CT angiography of the carotid arteries. In discussion, we discuss the possible embryological basis, incidence and prevalence of such finding and its possible clinical implications. CONCLUSION: One of the specific aspects of carotid arteries is their straightforward anatomy - the cervical portion of internal carotid artery, unlike the external carotid, does not give origin to any branches - this aspect is even used as a highlight for orientation, e.g. during ultrasound examination. However, although rare, variants exist, and sometimes can have clinical importance - in the endovascular access or surgical treatment.

Occipital artery-posterior inferior cerebellar artery bypass: a cadaveric feasibility study.

PURPOSE: To demonstrate that occipital artery (OA)-p1 posterior inferior cerebellar artery (PICA) bypass can be an alternative for complex posterior circulation aneurysms. METHODS: A far-lateral approach to craniotomy was performed on 20 cadaveric specimens, and the OA was obtained 'in-line.' Its length, diameter, and the number of p1/p2 and p3 segmental perforators were determined, and the relationship between the caudal loop and cerebellar tonsil position was also assessed. The distance between the PICA's origin and the cranial nerve XI (CN XI), the buffer length above the CN XI after dissection, the OA length required to complete the OA-p1/p3 PICA bypass, and the p1 and p3 segment diameters were all measured. A bypass training practical scale (TSIO) was used to evaluate the quality of the anastomosis. RESULTS: All specimens underwent OA-p1 PICA end-to-end bypass and had favorable results for the TSIO score, 15 sides underwent OA-p3 PICA end-to-side bypass, and the other bypass protocols were less common. The buffer length above the CN XI after dissection, the distance between the PICA's origin and the CN XI, and the first perforator were all of sufficient length. The direct length of the OA needed to complete the OA-p1 PICA end-to-end bypass was significantly less than the available length and the OA-p3 PICA end-to-side bypass, with the OA matching the p1 segment diameter. The number of p1 perforators was less than that of p3, and the OA diameter was equal to that of the p1 segment. CONCLUSION: OA-p1 PICA end-to-end bypass is a feasible alternative in cases in which p3 segment has high caudal loops or anatomic anomalies.

Hemorrhage due to a pseudoaneurysm on a dural-pial anastomosis after decompression for Chiari malformation type I: case report.

While intracranial aneurysms rarely develop after neurosurgical procedures, delayed pseudoaneurysm formation after foramen magnum decompression (FMD) has never been reported. A 52-year-old woman presented with an atypical subarachnoid hemorrhage in the posterior fossa 12 years after a FMD for symptomatic Chiari malformation type I was performed. A pseudoaneurysm on a dural-pial anastomosis was identified as the bleeding source and successfully occluded by endovascular means with full clinical recovery of the patient. Injury to the distal posterior inferior cerebellar artery related to surgery and postoperative infection likely caused formation of a dural-pial anastomosis. Additionally, hemodynamic stress or dissection may have contributed to delayed pseudoaneurysm formation and rupture.

Type 2 left proatlantal artery with normal left vertebral artery and association with an aberrant right subclavian artery and a bi-carotid trunk.

Type 2 proatlantal artery (PA) is a rare type of the carotid-vertebrobasilar anastomosis that arises from the external carotid artery and enters the posterior fossa via the foramen magnum (FM). The type 2 PA is usually large and takes a similar course to the occipital artery (OA). The peripheral branch of the OA arises from the distal segment, just proximal to the FM. The ipsilateral vertebral artery (VA) is usually aplastic or hypo-plastic. We diagnosed a case of relatively small type 2 left PA in a patient with a normally developed ipsilateral VA. Furthermore, the patient had an aberrant right subclavian artery associated with a bi-carotid trunk. The combination of these extracranial arterial variations has not been reported in the relevant English language literature.

Novel Vascular Anastomoses and Moyamoya Disease in a Woman with Down Syndrome.

A 56-year-old woman with Down syndrome presented with right-sided weakness and dysarthria, and was found on CT/CTA to have a left middle cerebral artery infarct secondary to moyamoya disease. Her left posterior inferior cerebellar artery (PICA) was fed both by the left vertebral artery, and the left ascending pharyngeal artery (APA), with a variant origin from the internal carotid artery (ICA), then passing through the jugular foramen (Figure 1). Her right PICA originated exclusively from her right occipital artery, also via the jugular foramen (Figure 2). The left vertebral artery originated directly from the aortic arch, whereas the right vertebral artery originated from the brachiocephalic trunk. In addition, she had a trifurcated anterior cerebral artery (ACA), and just prior to this trifurcation, her left ACA was partially supplied by the left ICA, via a superior hypophyseal artery. This case is noteworthy for several reasons. First, though it is exceedingly rare to have the PICA supplied by the jugular branch of the APA, this is the first reported case with an ICA origin of that APA.1,2 The fact that both PICAs in this patient originate from the anterior circulation should remind clinicians that in unexplained posterior circulation infarctions, vascular anatomy should be explored, as carotid-vertebrobasilar anastomoses such as these are rare, but possible. Lastly, the conjunction of moyamoya disease and anomalies of the vertebrobasilar system in a patient with Down syndrome raises interesting questions about the influence of trisomy 21 on the developing vasculature. Connections from the APA to the vertebrobasilar system are hypothesized to result from a lack of regression of an embryological anastomosis, in line with the more common persistent trigeminal and persistent hypoglossal arteries.1 Patients with moyamoya disease have a significantly higher rate of persistent carotid-vertebrobasilar anastomoses than the general population,3 and are also 26 times more likely to have Down syndrome.4 Correspondingly, patients with Down syndrome have significantly higher levels of moyamoya disease, and are more than 10 times as likely as the general population to have abnormalities of the Circle of Willis5 and vertebral arteries.6 Several genes on chromosome 21 are known to affect angiogenesis, namely collagen XIII/endostatin (COL18A1), DYRK1A, and Down syndrome candidate region 1 (DSCR1), possibly through inhibition of VEGF activity.7 Whether additional copies of these genes are responsible for the anomalous vascular development seen in Down syndrome, in turn predisposing to the development of moyamoya disease, could benefit from further exploration.

Ruptured aneurysm arising at anterior spinal artery as the collateral circulation with bulbar artery supply to posterior inferior cerebellar artery treated by proximal occlusion and occipital artery-posterior inferior cerebellar artery bypass: a case report and literature review.

The cases of aneurysms arising from collateral vessels that supply the posterior inferior cerebellar artery (PICA) are so exceptionally rare that there is no consensus on the optimal treatment. In this report, a patient was presented with subarachnoid hemorrhage caused by a fusiform aneurysm on the right anterior spinal artery, which formed an anastomosis network with bulbar artery and the vessels supplying to the right PICA. We chose to perform proximal occlusion on the anterior spinal and bulbar arteries, using occipital artery-PICA bypass. Our case was the first where proximal occlusion was used concurrently with vascular reconstruction to treat a ruptured aneurysm of collateral vessels supplying to PICA.

Occipital artery-anterior cerebral artery bypass with posterior auricular artery-middle cerebral artery bypass for stenosis of the internal carotid artery bifurcation.

Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass, and STA-anterior cerebral artery (ACA) bypass, are options for direct revascularisation of anterior circulation. However, some patients don't have a suitable STA to use as a donor, so an alternative procedure must be performed. A 59-year-old, right-handed man presented with dysphasia and right-sided hemiparesis due to a transient ischaemic attack. Imaging studies revealed severe stenosis of the left internal carotid artery bifurcation. Iodoamphetamine single photon emission computed tomography demonstrated reduced cerebrovascular reserve capacity in the left hemisphere. The patient was started on antiplatelet therapy, but the ischaemic attacks persisted after one month. Thus, revascularisation of the ACA and MCA territories was considered. Digital subtraction angiography revealed prominence in the left occipital artery (OA) and posterior auricular artery (PAA), while the left STA was hypoplastic, terminating at the squamous suture level. Therefore, anastomoses were performed between both the OA and ACA and the PAA and MCA. Revascularisation was successful, and the ischaemic attacks disappeared. OA-ACA bypass, together with PAA-MCA bypass, may be effective for wide cerebral revascularisation when the STA is not available.

A rare case report: bilateral occipital artery arising from the vertebral artery.

BACKGROUND: Variations of the origin of the occipital artery (OA) can be considered as congenital anomalies that are often asymptomatic and detected incidentally on angiography or during cadaver dissection. While OA normally originates from the posterior aspect of the external carotid artery (ECA), recent evidence also reflects that OA may infrequently originate from the internal carotid artery (ICA); however, OA originating from the vertebral artery (VA) is a highly rare phenomenon. CASE PRESENTATION: In a 54-year-old female patient with the complaint of left hemiparesis, computed tomography (CT) angiography revealed nonstenotic calcified plaques at the beginning of right ICA where common carotid artery (CCA) bifurcates. We also incidentally observed that bilateral OA originated from the VA using maximum intensity projection (MIP) technique. In addition to this rare variation, CT angiography showed the osseous anomaly termed as high-riding VA (HRVA) in the C1/2 vertebral space of the V3 segment of the VA. CONCLUSION: To the best of our knowledge, a case of bilateral OA originating from the VA has not been reported to date. We believe that recognition of this rare variation may contribute to the relevant literature and it is of importance to consider this variation in radiological imaging and surgical procedures involving this region.

Occipital artery arising from the cervical internal carotid artery at the level of the C2 vertebral body: three cases detected utilizing magnetic resonance angiography.

We incidentally observed the occipital artery (OA) arising from the cervical internal carotid artery (ICA) at the level of the C2 vertebral body on magnetic resonance (MR) angiography in three patients. In the rare case in which the OA arises from the ICA, it is generally at its origin. The OA arises from the cervical ICA when all but the distal part of the anastomosis of the primitive proatlantal artery between the ICA and vertebral artery persists. Careful review of MR angiographic images is important to detect rare arterial variations, and both partial maximum-intensity-projection images and source images aid their identification on MR angiography.

Anatomy of the greater occipital nerve block in infants.

BACKGROUND: Pain relief for posterior fossa craniotomies as well as occipital neuralgia, are indications for the use of the greater occipital nerve block in children. The greater occipital nerve originates from the C2 spinal nerve and is accompanied by the occipital artery as it supplies the posterior scalp. AIMS: The aim of this study was to develop a unique, yet simple technique for blocking the greater occipital nerve in children through the evaluation of the anatomy of this nerve and the accompanying occipital artery in the occipital region. METHODS: The greater occipital nerve and occipital artery were dissected and exposed in six formalin-fixed cadavers (five infants [average age of 51.4 days] and one 2-year-old) from the Department of Anatomy, University of Pretoria. Measurements between the nerve and selected bony landmarks were obtained. The relationship between the greater occipital nerve and the occipital artery at the trapezius muscle hiatus was also evaluated. RESULTS: The greater occipital nerve is on average 22.6 ± 5.6 mm from the external occipital protuberance in infants. The average width of the medial three fingers measured at the proximal interphalangeal joint, for each respective cadaver is 20.4 ± 4.0 mm, with a strong correlation coefficient of 0.97 between the aforementioned distances. In 83.3% of the specimens, the occipital artery lies lateral to the greater occipital nerve at the trapezius muscle hiatus. CONCLUSION: In infants, the greater occipital nerve can be blocked approximately 23 mm from the external occipital protuberance, medial to the occipital artery. This distance is equal to the width of the medial three fingers at the proximal interphalangeal joint of the patient.

Carotid-vertebral artery bypass with saphenous vein graft for symptomatic vertebrobasilar insufficiency.

OBJECTIVESymptomatic steno-occlusion of the proximal vertebral artery (VA) or subclavian artery (ScA) heralds a poor prognosis and high risk of stroke recurrence despite medical therapy, including antiplatelet or anticoagulant drugs. In some cases, the V2 segment of the cervical VA is patent and perfused via collateral vessels. The authors describe 7 patients who were successfully treated by external carotid artery (ECA)-saphenous vein (SV)-VA bypass.METHODSSeven cases involving symptomatic patients were retrospectively studied: 3 cases of V1 segment occlusion, 2 cases of severe in-stent restenosis in the V1 segment, and 2 cases of occlusion of the proximal ScA. All patients underwent ECA-SV-VA bypass. The ECA was isolated and retracted, and the anterior wall of the transverse foramen was unroofed. The VA was exposed, and then the 2 ends of the SV were anastomosed to the VA and ECA in an end-to-side fashion.RESULTSSurgical procedures were all performed as planned, with no intraoperative complications. There were 2 postoperative complications (severe laryngeal edema in one case and shoulder weakness in another), but both patients recovered fully and measures were taken to minimize laryngeal edema and its effects in subsequent cases. All patients experienced improvement of their symptoms. No new neurological deficits were reported. Postoperative angiography demonstrated that the anastomoses were all patent, and analysis of follow-up data (range of follow-up 12-78 months) revealed no further ischemic events in the vertebrobasilar territory.CONCLUSIONSThe ECA-SV-VA bypass is a useful treatment for patients who suffer medically refractory ischemic events in the vertebrobasilar territory when the proximal part of the VA or ScA is severely stenosed or occluded but the V2 segment of the cervical VA is patent.

Anomalous anastomosis between the external carotid artery and vertebrobasilar artery via the hypoglossal canal: a case report and review of literature.

We report a case of an anomalous anastomosis formed between the external carotid artery (ECA) and the vertebrobasilar artery (VBA) and passing through the hypoglossal canal. A carotid-vertebrobasilar anastomosis of this kind is typically considered a variant of persistent primitive hypoglossal artery which usually originates from the internal carotid artery. However, the anastomotic vessel in this case had a common trunk with the occipital artery (OA), a remnant of the primitive proatlantal artery. The proximal and distal parts of the anastomotic vessel seemed to have been derived from the primitive proatlantal artery and the primitive hypoglossal artery, respectively. Thus, we propose that this ECA-VBA anastomosis, which passed through the hypoglossal canal and had a common trunk with the OA, be referred to as a dilated primitive hypoglossal-proatlantal anastomosis; that is, a dilated ascending pharyngeal artery rather than a variant of persistent primitive hypoglossal artery.

Anatomical consideration of the occipital cutaneous nerves and artery for the safe treatment of occipital neuralgia.

There is no standardized approach to the greater occipital nerve (GON) block technique for treating occipital neuralgia. The aim of the present study was to validate the previously-suggested guidelines for conventional injection techniques and to provide navigational guidelines for safe GON block. The GON, lesser occipital nerve (LON) and occipital artery (OA) were carefully dissected in the occipital region of embalmed cadavers. Using a 3 D digitizer, the GON, LON, and OA were observed on the two reference lines. The distances between the landmarks were recorded and statistically analyzed. On the superior nuchal line, the mean distances between the external occipital protuberance (EOP) and the most medial branch of the GON was 33.5 mm. The mean distance between the EOP and the most medial branch of the OA was 37.4 mm. On the EOP-mastoid process (MP) line, the GON was on the medial third and the LON the lateral third of the EOP-MP line. The safe injection points on the EOP-MP line are about 3 cm from the EOP, 1 cm inferior parallel to the EOP-MP line, and about 3 cm away from the MP. Clin. Anat. 31:1058-1064, 2018. © 2018 Wiley Periodicals, Inc.

Occipital artery arising from the internal carotid artery: a case report.

Variations of the branches of the external carotid artery have been well documented in the available literature. However, variation of the occipital artery arising from the internal carotid artery is extremely rare case. A 42-year-old man patient who suffered from subarachnoid hemorrhage with suspicious vascular anomalies was found to have this variation on the right side by angiography during selective catheterisation of main carotid artery for vascular mapping. Our literature searches revealed that there was rare case such variations. We think that this variation should contribute to literature and should be kept in mind during surgical, radiological and diagnostic procedures.