Carotid petrous segment aneurysm presenting as hypoglossal nerve palsy

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.

The Hypoglossal nerve

The hypoglossal nerve is the 12th cranial nerve, exiting the brainstem in the preolivary sulcus, passing through the premedullary cistern, and exiting the skull through the hypoglossal canal. This is a purely motor nerve, responsible for the innervation of all the intrinsic tongue muscles (superior longitudinal muscle, inferior longitudinal muscle, transverse muscle, and vertical muscle), 3 extrinsic tongue muscles (styloglossus, hyoglossus, and genioglossus), and the geniohyoid muscle. Magnetic resonance imaging (MRI) is the best imaging exam to evaluate patients with clinical signs of hypoglossal nerve palsy, and computed tomography may have a complementary role in the evaluation of bone lesions affecting the hypoglossal canal. A heavily T2-weighted sequence, such as fast imaging employing steady-state acquisition (FIESTA) or constructive interference steady state (CISS) is important to evaluate this nerve on MRI. There are multiple causes of hypoglossal nerve palsy, being neoplasia the most common cause, but vascular lesions, inflammatory diseases, infections, and trauma can also affect this nerve. The purpose of this article is to review the hypoglossal nerve anatomy, discuss the best imaging techniques to evaluate this nerve and demonstrate the imaging aspect of the main diseases that affect it.

The Glossopharyngeal, Vagus and Accessory nerves: Anatomy and Pathology

The glossopharyngeal, vagus, and accessory nerves are discussed in this article, given their intimate anatomical and functional associations. Abnormalities of these lower cranial nerves may be intrinsic or extrinsic due to various disease processes. This article aims to review these nerves' anatomy and demonstrates the imaging aspect of the diseases which most commonly affect them.

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.