Isolated peripheral hypoglossal palsy caused by a kinking of the left vertebral artery (hypoglossal vertebral entrapment syndrome)

Hypoglossal Nerve Neuropathies-Analysis of Causes and Anatomical Background

The hypoglossal nerve is the last, and often neglected, cranial nerve. It is mainly responsible for motor innervation of the tongue and therefore the process of chewing and articulation. However, tumors, aneurysms, dissections, trauma, and various iatrogenic factors such as complications after surgeries, radiotherapy, or airway management can result in dysfunction. Correct differential diagnosis and suitable treatment require a thorough knowledge of the anatomical background of the region. This review presents the broad spectrum of hypoglossal neuropathies, paying particular attention to these with a compressive background. As many of these etiologies are not common and can be easily overlooked without prior preparation, it is important to have a comprehensive understanding of the special relations and characteristic traits of these medical conditions, as well as the most common concomitant disorders and morphological traits, influencing the clinical image. Due to the diverse etiology of hypoglossal neuropathies, specialists from many different medical branches might expect to encounter patients presenting such symptoms.

Isolated hypoglossal nerve neuropathy in vertebral dolichoectasia: Microvascular decompression by vessel transposition with Teflon cuff

Background:

A clinical case of isolated unilateral hypoglossal nerve (HN) neuropathy, which spontaneously occurred from vertebral artery dolichoectasia and was cured by a new method of microvascular decompression by transposition of the vertebral artery using the Teflon cuff.

Case Description:

A young patient with an anamnesis of the disease for more than 4 years and complaints of a deviation of the tongue to the right and dysarthria was examined. MRI of the brain revealed compression of the medulla oblongata by an elongated, dilated, and deformed right vertebral artery. Compression of the medulla oblongata and HN was confirmed during surgery. A transposition of the vertebral artery was performed using a Teflon cuff in the ventral direction to the clivus. Three months after surgery, positive dynamics was noted in the form of regression of dysarthria and improvement of mobility and trophic language.

Conclusion:

Thus, isolated HN neuropathy as a result of compression by an elongated, dilated, and deformed vertebral artery is a rare neurological disease that can be successfully treated by transposition using a Teflon cuff.

Unilateral isolated hypoglossal nerve palsy due to pathologically adherent PICA fusiform aneurysm - A case report

Background:

Isolated hypoglossal nerve palsy due to mechanical compression by a vascular lesion is rare.

Case Description:

We report the case of a 72-year-old man who presented with a 4-year history of swallowing disturbance and subsequently progressively worsening left-sided tongue atrophy. He was referred to our department by a neurologist due a magnetic resonance imaging detected left vertebral artery compression of the medulla. Neurological examination was unremarkable except for left hypoglossal nerve dysfunction, which presented as left-sided atrophy and impaired movement of the tongue. Three-dimensional computed tomography angiography showed proximal left posterior inferior cerebellar artery (PICA) origin fusiform aneurysm. Microvascular decompression was done through a left transcondylar fossa approach. Intraoperative findings were thickened arachnoid around the lower cranial nerves, fusiform aneurysm of the left PICA at its origin from the left vertebral artery which was severely adherent to and compressing the left hypoglossal nerve rootlets.

Conclusion:

The PICA has a very close relationship to the hypoglossal nerve, and its fusiform dilatation could cause isolated hypoglossal nerve dysfunction. Pathological adhesions between hypoglossal rootlets and the PICA aneurysm wall could be a possible contributor in the development and progression of hypoglossal nerve palsy.

Microvascular decompression for hypoglossal nerve palsy secondary to vertebral artery compression: A case report and review of the literature

Background:

Neurovascular-compression syndrome (NCS) is described as a prominent pathological contact between cranial nerves and vessels. Trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia are typical clinical entities associated with NCS. On the other hand, the hyoglossal nerve is rarely affected by NCS.

Case Description:

We present a case of hypoglossal nerve palsy (HNP) secondary to vertebral artery (VA) compression. A 47-year-old man presented to our hospital with a 1-month history of dysarthria and dysphagia. Neurological examination revealed left HNP, with an intact swallowing reflex and no oropharyngeal or palatal weakness. Magnetic resonance imaging (constructive interference in steady state) revealed left hypoglossal nerve compression by the V4 segment of the left atherosclerotic VA. He underwent microvascular decompression (MVD) surgery. Intraoperatively, the VA was compressing the hypoglossal nerve. The left VA was moved and attached to the dura matter using a polytetrafluoroethylene (Teflon®) sheet and fibrin glue. Postoperatively, the patient exhibited gradual recovery of HNP in 3 months without dysfunction of lower cranial nerves.

Conclusion:

In patients with isolated HNP, vascular compression should be considered as a cause of these symptoms, and subsequent MVD can lead to resolution.

Intermittent hypoglossal nerve palsy caused by a calcified persistent hypoglossal artery: an uncommon neurovascular compression syndrome

Neurovascular compression is assumed to cause symptoms like trigeminal neuralgia, hemifacial spasm and vestibular paroxysmia. We present a patient with recurrent episodes of transient dysarthria due to isolated right hypoglossal nerve (HN) palsy. We describe the first case of a calcified persistent hypoglossal artery (PHA) as the putative cause of a hypoglossal neurovascular compression syndrome. Our patient received a daily low-dose medication of carbamazepine resulting in complete relief of symptoms. In conclusion, PHA is not only an anatomic variation but also a possible cause of a neurovascular compression syndrome leading to intermittent HN palsy.

Resolution of isolated unilateral hypoglossal nerve palsy following microvascular decompression of the intracranial vertebral artery

Isolated hypoglossal nerve paresis due to mechanical compression from a vascular lesion is very rare. We present a case of a 32-year-old man who presented with spontaneous abrupt-onset dysarthria, swallowing difficulty and left-sided tongue atrophy. Brain computed tomographic angiography and magnetic resonance imaging of the brainstem demonstrated an abnormal course of the left vertebral artery compressing the medulla oblongata at the exit zone of the hypoglossal rootlets that was relieved by microvascular decompression of the offending intracranial vertebral artery. This case supports the hypothesis that hypoglossal nerve palsy can be due to nerve stretching and compression by a pulsating normal vertebral artery. Microvascular decompression of the intracranial nerve and careful evaluation of the imaging studies can resolve unexpected isolated hypoglossal nerve palsy.

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.

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.

Cochlear vertebral entrapment syndrome: a case report

The authors describe a patient with isolated involvement of vestibulocochlear nerve by a huge vascular loop from vertebral dolichoectasia. No other neurological deficit was found except for unilateral hearing loss. Abnormal brainstem auditory evoked potential study indicated a retrocochlear lesion. The brain computed tomography (CT) and magnetic resonance imaging (MRI) studies demonstrated an abnormally enhanced vascular lesion impinged on the left porus acusticus with a displacement of the brainstem to the right. There was no infarction in the brainstem. A cerebral angiography demonstrated a megadolichoectatic horizontal loop at the intracranial portion of the left vertebral artery. There was no thrombus or atherosclerosis in the vertebrobasilar system. A mechanical compression by a vascular loop is the only possible pathogenesis for hearing loss. The authors diagnose this condition as cochlear vertebral entrapment syndrome.

Isolated hypoglossal nerve palsy due to an anomalous vertebral artery course: report of two cases

The authors report two patients with isolated unilateral tongue atrophy. Magnetic resonance imaging (MRI) of the brain stem and angio-MRI demonstrated a dolichovertebral artery with an abnormal course compressing the medulla oblongata at the emergence of the hypoglossal rootlets. The semeiological observation of a sectorial and not uniform distribution of atrophy in the half-affected tongue is discussed in relation to the lesional site.