Persistent hypoglossal artery with hypoplasia of the vertebral and posterior communicating arteries.

We observed a rare case of the right persistent hypoglossal artery (PHA) in the posterior cranial fossa of a deceased 74-year-old Japanese man who did not have any clinical manifestations related to this anomaly when alive. The large-sized PHA originating from the cervical internal carotid artery passed through the hypoglossal canal together with the hypoglossal nerve and reached the posterior cranial fossa to anastomose the basilar artery. In addition, the ipsilateral vertebral artery and bilateral posterior communicating arteries were hypoplastic. Here, we discuss the developmental mechanisms underlying the formation of the PHA and the spectrum of diseases related to its presence.

[Hypoglossal artery and carotid endarterectomy. Case report]. / Persistenza dell'arteria ipoglossa ed endoarteriectomia carotidea. Case report

The persistence of hypoglossal artery is a rare malformation. Association of carotid stenosis with persistent hypoglossal artery can lead to cerebral posterior symptoms due to ischemia intolerance. The Authors report a case of unexpected intraoperative detection of this anomaly in a patient with high grade stenosis of the right internal carotid artery. Right carotid endarterectomy was performed, and no shunt was used. The postoperative course was normal. The literature was reviewed.

A successful treatment with carotid arterial stenting for symptomatic internal carotid artery severe stenosis with ipsilateral persistent primitive hypoglossal artery: case report and review of the literature.

A 68-year-old male presented with a syncopal attack subsequent to acute myocardial infarction. His ultrasonographic and radiological examination revealed severe left internal carotid artery (ICA) stenosis and the presence of a persistent primitive hypoglossal artery (PPHA) immediately distal to the stenosis. The bilateral anterior and left middle cerebral arteries, and the vertebrobasilar system were opacified via the stenotic ICA. Carotid arterial stenting was selected as the treatment method because the lesion was high and a shunt placement during carotid endarterectomy was considered to be technically difficult. A self-expanding stent was successfully deployed with flow control, and the patient was discharged six days after surgery without any neurological deficit. There are sixteen reported cases including ours of PPHA associated with ICA stenosis presenting with ischemic attacks of the vertebrobasilar system. To the best of our knowledge, the current case is the first report of a cervical ICA stenosis with ipsilateral carotid-basilar anastomosis treated with carotid arterial stenting.

Medullary microvessel degeneration in multiple system atrophy.

Multiple system atrophy (MSA) is a rare and fatal early-onset autonomic disorder which is characterised by Parkinsonism and orthostatic hypotension (OH). The pathophysiology of MSA is not fully understood but key features include the depletion of medullary autonomic neurons and presence of glial cellular inclusions. We hypothesise that the degeneration of medullary autonomic microvessels is an additional finding in MSA. Using digital pathology we quantified basement membrane collagen (Coll IV), smooth muscle actin (alpha-actin) and endothelial glucose transporter (Glut 1) expression in medullary autonomic nuclei of 8 MSA and 8 OH cases, compared with 12 controls with no autonomic dysfunction. We found decreased Coll IV (p=0.000) and Glut 1 (p=0.000) but not alpha-actin expression, in medullary autonomic nuclei of MSA, but not OH cases compared with control subjects. Medullary microvessel degeneration in MSA may be secondary to the primary neuro-glial pathogenesis of the disorder, and could accelerate its ageing-related progression.

Isolated hypoglossal nerve palsy due to a vascular anomaly.

The case of a patient with an unusual cause of an isolated hypoglossal nerve palsy is presented. Magnetic resonance (MR) imaging demonstrated marked dilatation and ectasia of the right vertebral artery and basilar artery, thereby causing compression of the brainstem. It is therefore proposed that a dilated vascular loop compression of the nerve rootlets, as they exit the medulla, has caused the hypoglossal nerve palsy. This case demonstrates that excellent images can be obtained from MR imaging, and also emphasises that other pathologies must be considered in the differential diagnosis of hypoglossal nerve palsy.

Surgical anatomy of the cervical segment of the hypoglossal nerve.

The surgical anatomy of the extracranial segment of the hypoglossal nerve (HN) has been sparsely investigated in the literature. This article studies the course and anatomical and topographic relationships of the HN in 23 formalin fixed cadavers bilaterally dissected under a surgical microscope. The descriptive anatomy is presented with relevant clinical and surgical implications.

Persistent carotid-vertebrobasilar anastomoses: how and why differentiating them?

The persistent carotid-vertebrobasilar anastomoses (PCVBA) can be explained by an interruption of the vertebrobasilar system (VBS) embryogenesis. We present two very rare cases of persistent anastomoses: a hypoglossal artery and a type I proatlantal artery, insisting on the angiographic criteria allowing differentiation. After a brief review of the embryogenesis of the VBS, we describe the different types of persistent anastomoses (hypoglossal, type I and II proatlantal, trigeminal and otic arteries). We will insist on the potential risks, not well-known, but typical of each anastomosis. PCVBA usually are incidental findings but imaging follow-up may be required since aneurysms may develop.

Detailed anatomy of the intracranial segment of the hypoglossal nerve: neurovascular relationships and landmarks on magnetic resonance imaging sequences.

OBJECT: The thin hypoglossal nerve can be very difficult to distinguish on magnetic resonance (MR) images. The authors used a combination of sequences to increase the reliability of MR imaging in its demonstration of the 12th cranial nerve as well as to assess the course of the nerve, display its relationships to adjacent vessels, and provide landmarks for evaluating the nerve in daily practice. METHODS: The study group consisted of 34 volunteers (68 nerves) in whom a three-dimensional (3D) Fourier-transformation constructive interference in steady-state (CISS) sequence and a 3D T1-weighted contrast-enhanced magnetization-prepared rapid-acquisition gradient-echo (MPRAGE) sequence were applied. Two trained neuroradiologists collaboratively identified the hypoglossal trigone, preolivary sulcus, 12th cranial nerve, posterior inferior cerebellar artery, vertebral artery, 12th nerve root sleeve, and the hypoglossal canal on each side. The 3D CISS sequence successfully demonstrated the hypoglossal trigone (100% of images), 12th nerve root bundles (100% of images), and 12th nerve sleeves (88.2% of images). The canalicular segment was exhibited with the aid of plain 3D CISS sequences in 74% of images and by using contrast-enhanced 3D CISS sequences and contrast-enhanced MPRAGE sequences in 100% of images. The landmarks that proved useful to identify the cisternal segment of the 12th cranial nerve included the hypoglossal trigone, preolivary sulcus, and 12th nerve root sleeve. Neurovascular contact was identified in 61% of root bundles. The roots were distorted in 44% of these contacts. CONCLUSIONS: The contrast-enhanced 3D CISS sequence consistently displayed the cisternal segment as well as the canalicular segments of the hypoglossal nerve and is, therefore, the best sequence to visualize the complete cranial course of this nerve. Landmarks such as the 12th nerve sleeves can assist in the identification of this nerve.

Cavernous malformation of the hypoglossal nerve: case report and review of the literature.

OBJECTIVE: To describe a patient who presented with a hypoglossal nerve palsy caused by a cavernous malformation, review the literature on cavernous malformations associated with cranial nerves and the differential diagnosis of hypoglossal palsy. RESULTS: Partial resection of the lesion was achieved and the diagnosis of cavernous malformation proven histologically. CONCLUSIONS: Involvement of a cranial nerve by a cavernous malformation is very uncommon and the facial nerve is the example most frequently reported. This case report adds another possible site for this rare occurrence.

Microsurgical anatomy of the facial nerve trunk.

Dissection and manipulation of the facial nerve (FN) trunk between its exit from the cranial base through the stylomastoid foramen (SMF) and its bifurcation is a critical step in various otologic, plastic and neurosurgical procedures. This study demonstrates the anatomical relationships and variability of the FN trunk with emphasis on some important morphometric data, particularly with relevance to hypoglossal-facial nerve anastomosis (HFA). Bilateral microsurgical dissection was performed on twenty-three human cadavers fixed with formalin. The whole trunk of the FN was exposed, its diameter at the SMF and its length were measured, its branches were observed and the site of its bifurcation was determined. Anastomotic connections with other nerves and blood supply of the trunk were studied. The FN invariably emerged from the cranial base through the SMF. Its diameter upon its emergence from the foramen was 2.66 +/- 0.55 mm. Two branches consistently originated from the trunk: the posterior auricular nerve and the nerve to the digastric muscle. Less consistent were the communicating branch with the glossopharyngeal nerve and the nerve to the stylohyoid muscle. The bifurcation of the FN occurred before its penetration into the parotid gland in 15% of cases and within the gland in 85%. The length of the FN trunk was 16.44 +/- 3.2 mm. Anastomoses between the FN and other nerves were observed in one-third of the dissections. The blood supply to the FN trunk was provided by the stylomastoid artery that was identified in 91% of cases. Understanding the microsurgical anatomy of the FN trunk is essential for performing any surgical procedure in the relevant region. Surgical implications of this study are presented with emphasis on HFA surgery.

Anatomy and blood supply of the lower four cranial and cervical nerves: relevance to surgical neck dissection.

This study is a continuation of previous work searching for possible anatomic reasons to explain variable and usually unpredictable postoperative pain and dysfunction after the same nerve losses with similar neck dissection operations. The study consisted of dissections of 19 deceased unpreserved elderly subjects arterially injected with dyed latex. Of the 19 subjects, 14 had brain stem and cervical spinal cord dissections, and all had neck dissections. The findings suggested two possible anatomic reasons for the pain and dysfunction: (i) The intracranial anatomy of the lower four cranial nerves, the glossopharyngeal (IX), the vagus (X), the spinal accessory (XI), and the hypoglossal (XII), was just as variable as the previously reported peripheral spinal accessory nerve plexus; and (ii) Both the intracranial and neck dissections indicated that the blood supply to the lower four cranial and cervical nerves, particularly to the brachial plexus, could be impaired by atherosclerosis and/or neuroforaminal impingement or operative loss. This loss of blood supply theoretically could result in ischemia as another possible cause of postoperative pain and dysfunction. It is concluded that because of the potential importance of each nerve and vessel, often unknown at operation, it is very important to spare as many of them as possible to avoid subsequent painful impairment.

Persistent external carotid-vertebrobasilar anastomosis via the hypoglossal canal.

A persistent external carotid-vertebrobasilar anastomosis, associated with intracranial aneurysms, was identified. The anomalous vessel passed through the hypoglossal canal, and was possibly a variant of the persistent primitive hypoglossal artery.

[Ruptured persistent primitive hypoglossal artery aneurysm: case report].

Persistent primitive hypoglossal artery is less common than persistent primitive trigeminal artery. About one hundred examples of such hypoglossal arteries have been demonstrated by angiography. The origin of persistent primitive hypoglossal artery is the cervical segment of the internal carotid artery, usually at the level of the first to second cervical vertebrae. The artery then enters, with varying degrees of tortuosity, the anterior condyloid (hypoglossal) canal and joints the basilar artery immediately above its lower end. When enlargement of this canal is identified, the presence of a persistent primitive hypoglossal artery should be strongly suspected. The homolateral vertebral artery is frequently hypoplasia. A 66-year-old man was brought to our hospital due to faintness. CT showed thick subarachnoid hemorrhage. Angiography showed that a persistent primitive hypoglossal artery aneurysm was present, but the posterior communicating artery was absent. Right vertebral angiography showed extravasation due to re-rupture of the aneurysm. An operation was performed at day 0 using the left transcondylar approach despite deterioration of SAH grading. Intraoperative re-rupturing occurred and the lower cranial nerves clustered around the aneurysm, so the aneurysm was partially clipped on the dome. The second angiography was carried out at day 10, and there was no vasospasm. Palsy of the lower cranial nerves appeared transiently. A ventricle-peritoneum shunt was required due to normal pressure hydrocephalus, but the patient was discharged with no neurological deficits.

The blood supply of the hypoglossal nerve and its relevance to carotid endarterectomy.

Since the hypoglossal nerve is liable to injury during carotid endarterectomy and similar procedures, its blood supply was examined in microinjection studies of human cadavers. The nerve is supplied by arteries that arise from the ascending pharyngeal artery as it exits from the hypoglossal canal, the occipital artery as the nerve passes under its branch to the sternomastoid muscle, direct branches from the external carotid artery, and branches from the ascending pharyngeal artery just near the bifurcation of the common carotid artery. Within and close to the tongue, the nerve is supplied by branches from the lingual artery. Damage to the vessels supplying the nerve may account for some cases of hypoglossal palsy after carotid endarterectomy. Possible mechanisms are ischaemia, thermal or electrical injury from diathermy current conducted to the nerve, or intraneural haematoma from rupturing one or more of these fine vessels.

Severe stenosis of the internal carotid artery presenting as loss of consciousness due to the presence of a primitive hypoglossal artery: a case report.

BACKGROUND: Symptoms of ischemic attacks in the internal carotid system usually involve focal cerebral dysfunction, i.e., hemiparesis or aphasia. However, an ischemic attack in the vertebrobasilar artery system usually presents with combined symptoms. The variety of manifestations included in the vertebrobasilar profile makes the potential pattern of symptoms considerably more variable and complex than that in the carotid system. Manifestations can include syncope and also vertigo. METHOD AND RESULTS: A 42-year-old woman experienced frequent attacks of faintness with vertigo. Angiography demonstrated severe stenosis of the left internal carotid artery with a persistent primitive hypoglossal artery just distal to the stenosis. The right internal carotid artery was normal and cross circulation through the anterior communicating artery was not well developed. Both vertebral arteries were hypoplastic. The patient underwent carotid endarterectomy and, thereafter the episodes of syncope completely disappeared. CONCLUSION: It was supposed that global ischemia including the brain stem occurred because of stenosis of the left internal carotid artery attributable to the presence of a primitive hypoglossal artery.