The hypoglossal nerve, also known as the XII cranial nerve, arises from the medulla oblongata, carriers only motor fibers and supplies the muscles of the tongue [1] [2]. Its travel, from the point of origin to the tissue it innervates, is quite long and is generally divided into five segments - medullary, cisternal (intracranial), skull base, nasopharyngeal/oropharyngeal and carotid [1] [2]. Many pathologies have been described in the literature when it comes to the damage of the hypoglossal nerve in any of the mentioned segments, and it is estimated that tumors, such as nasopharyngeal carcinomas, gliomas, acoustic neuromas, chordomas, and metastases, are responsible for the majority of cases [2] [3] [4]. Other known causes include trauma [3], surgery-induced (examples being endotracheal intubation, cervical spine surgery, etc.) [5] [6] [7], and vascular changes (ischemia or hemorrhage) [1]. Signs and symptoms of hypoglossal nerve palsy are highly distinctive, the main feature being a unilateral weakness of the tongue [1]. In addition, the tongue may deviate toward the side of the damaged nerve (if the lesion is located inferior to the hypoglossal nerve nucleus) or contralaterally in the case of a supranuclear lesion [1]. Weakness is often accompanied by atrophy of the tongue, as well as fasciculations [1]. Furthermore, a number of patients might suffer from impaired speech (dysarthria) and swallowing difficulties (dysphagia), which may be severely debilitating [1] [3] [5] [6].

• Collapse

  Cranial computed tomography revealed dilatation of the ventricular system and diffuse cerebral edema, which had caused collapse of the basal cisterns. [nejm.org]

• Tongue Atrophy

  Abstract The authors report two patients with isolated unilateral tongue atrophy. [link.springer.com]

  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. [semanticscholar.org]

  The recovery of facial movement frequently comes at the expense of some degree of tongue atrophy and impairment of post-operative speech and eating. These problems can be largely overcome by utilizing a partial hypoglossal transfer. [methodistfacialparalysis.com]

  Symptoms: Symptoms of hypoglossal nerve palsy typically include unilateral or bilateral tongue weakness with deviation towards the affected side on tongue protrusion, tongue atrophy (with scalloping or accentuation of the midline groove), fasciculation [medigoo.com]

  Based on our method for identifying patients for review, the potential exists for missing cases in which the neuroradiologist did not include “hypoglossal palsy” or “tongue atrophy” in the radiology report. [ajnr.org]

• Fasciculation of the Tongue

  Lesions of the hypoglossal nerve Paralysis, atrophy and fasciculations of the tongue on the ipsilateral side (with nuclear or infranuclear lesions) Mild weakness of the tongue on the contralateral side (with supranuclear lesions) The "central" supranuclear [derangedphysiology.com]

  Definition This nerve controls all tongue movements. Nuclear or infranuclear lesions produce paralysis, atrophy, and fasciculations of the tongue on the involved side. [ncbi.nlm.nih.gov]

  Symptoms: Symptoms of hypoglossal nerve palsy typically include unilateral or bilateral tongue weakness with deviation towards the affected side on tongue protrusion, tongue atrophy (with scalloping or accentuation of the midline groove), fasciculation [medigoo.com]

  Clinically, marked deviation of the tongue to the right side with muscle fasciculation was evident. [nature.com]

• Hemiatrophy of the Tongue

  The tongue deviated toward the healthy side at rest and toward the affected side on protrusion. Hemiatrophy of the tongue with fatty displacement was demonstrated by means of T1-weighted magnetic resonance imaging. [ncbi.nlm.nih.gov]

  Intraoral examination of the patient revealed hemiatrophy of the tongue, on the right side, and the inability to completely deviate the tongue toward the left side of the mouth on protrusion. [anatomybox.com]

• Lacrimation

  lacrimal gland Motor (somatic) Muscles of facial expression Eyelid closing : orbicularis oculi muscle Jaw opening: posterior belly of the digastric muscle Hyoid elevation: stylohyoid muscle Efferent arm of the acoustic reflex ( stapedius muscle ) VIII [amboss.com]

  Additional tests For suspected intracranial or infratemporal injury, always perform a Schirmer test of tearing to assess lacrimal gland function. [emedicine.medscape.com]

  HC) is classified as a primary headache disorder, typically manifested as daily unilateral continuous headache with superimposed, normally severe, stabbing or throbbing pain, associated with cranial autonomic sigs such as ipsilateral ptosis, increase lacrimation [webmedcentral.com]

• Tongue Muscle Weakness

  With unilateral weakness or paralysis, the tongue will point to the affected side due to unopposed action of the normal muscle. Basic Science The nuclei are dorsal and medial in the medulla. [ncbi.nlm.nih.gov]

• Dysarthria

  We present a patient with recurrent episodes of transient dysarthria due to isolated right hypoglossal nerve (HN) palsy. [ncbi.nlm.nih.gov]

  Dysarthria that has progressed to a total loss of speech is referred to as anarthria. [dbpedia.org]

  MANAGMENT Speech therapy should be given Exercise for the treatment of dysarthria may help to improve tongue co-ordination and strength. [slideshare.net]

• Mononeuropathy

  Key words Hypoglossal nerve palsy Cranial mononeuropathy This is a preview of subscription content, log in to check access. Preview Unable to display preview. Download preview PDF. [link.springer.com]

  It is a rare condition in childhood where the mononeuropathies of the facial nerve are the commonest reported. Setting : Department of Head and Neck oncosurgery, Kidwai Memorial Institute of Oncology, Bangalore. [alliedacademies.org]

  Cranial mononeuropathy as the first sign of intracranial metastases. Ann Intern Med. 1969; 70 :49–54. [ PubMed : 4303303 ] [ncbi.nlm.nih.gov]

  […] associated with dengue have shown. [3], [5] To date, there is no established treatment for mononeuropathies following dengue though expectant management has shown to have a favorable outcome. [3], [5] This clear temporal relationship with dengue infection [neurologyindia.com]

  A cranial nerve mononeuropathy is a condition in which only a single cranial nerve or nerve group is damaged. [amboss.com]

• Myelopathy

  Neurologic complications of this involvement include pain, myelopathy, and cranial nerve (CN) palsies. However, hypoglossal nerve palsy (CN XII) is rarely diagnosed. [ncbi.nlm.nih.gov]

  Of interest, none of our 4 patients with CCJ ROFP hypoglossal palsy had myelopathy on neurologic examination, though imaging showed ventral cervicomedullary compression in 2 of the 4 patients. [ajnr.org]

  There was no suggestion of a myelopathy in the form of limb weakness or bladder bowel involvement. [jneuro.com]

• Slurred Speech

  Examination revealed pronounced dysarthria and slurred speech and inability to move and protrude his tongue, which was observed at rest in the floor of the mouth. [anesthesiology.pubs.asahq.org]

  Weakness of tongue muscles can result in slurred speech, affecting sounds particularly dependent on the tongue for generation (i.e., lateral approximants, dental stops, alveolar stops, velar nasals, rhotic consonants etc.). [18] Tongue strength may be [en.wikipedia.org]

• Papilledema

  Very rare examples of IIH with unilateral papilledema and pseudopapilledema, and of patients with headache, papilledema, and normal CSF pressure have been reported [2,3]. Conversely, IIH may occur without papilledema [4]. [webmedcentral.com]

  The neurological examination revealed bilateral papilledema and mild truncal ataxia, although weakness and atrophy of the tongue were not observed. [ncbi.nlm.nih.gov]

To make the diagnosis of a hypoglossal nerve palsy, the physician is obliged to perform a detailed physical examination and obtain a thorough patient history that should reveal any preexisting disorders or events that could predispose the patient to this neurological deficit. The unilateral weakness of the tongue can be readily observed during a properly conducted neurological exam and the assessment of cranial nerves. To test the hypoglossal nerve, the patient is asked to protrude his tongue, when the deviation (and possibly atrophy or fasciculations) to one side is apparent [3] [5] [6] [7]. In order to identify the underlying cause, however, a more detailed investigation is warranted, with imaging studies being the cornerstone. Computed tomography (CT) and magnetic resonance imaging (MRI) are both recommended for the evaluation of hypoglossal nerve palsy. CT is able to visualize the skeletal structures in greater detail, while soft-tissues are better defined using MRI, particularly when gadolinium is employed as a contrast [1]. In fact, either CT or MR angiography are of great value in the diagnosis of vascular insults [2].

Recognition of internal carotid artery dissection is critical for appropriate treatment and to minimise the risk of thromboembolic-ischaemic complications. [ncbi.nlm.nih.gov]

There was uncertainty around prognosis at onset due to the rarity of this condition. [ncbi.nlm.nih.gov]

Although the aetiological importance and ominous prognosis of neoplasia has been emphasized by others, our study suggests that an isolated hypoglossal nerve palsy may be benign and idiopathic. [link.springer.com]

Keywords: Hypoglossal nerve ; Paralysis ; Prognosis 1. Combarros O, Alvarez de Arcaya A, Berciano J. Isolated unilateral hypoglossal nerve palsy: Nine cases. J Neurol 1998;245:98–100. 2. Lee SS, Wang SJ, Fuh JL, Liu HC. [synapse.koreamed.org]

Neurophysiological examinations are commonly employed for prognostication after SCI, but whether neurophysiology could improve the functional prognosis based on clinical predictors remains open. [scinapse.io]

The prognosis for recovery seems better in secondary nerve palsy than in immediate palsy. It is therefore important to note the chronology of appearance of the deficit as this may have medico-legal consequences. [em-consulte.com]

Neuroradiological examinations and other investigations for etiology of hypoglossal nerve palsy and urticaria were normal. We suggest that all patients with hypoglossal palsy must be carefully evaluated for atypical findings and etiologies. [ncbi.nlm.nih.gov]

Results: Major etiologic categories included: postoperative (29.3%), idiopathic (15.1%), primary neoplastic (14.2%), metastatic malignancy (13.0%), inflammatory (7.3%), radiation (6.1%), and traumatic (4.1%). [mayoclinic.pure.elsevier.com]

It also represents a diagnostic challenge in every day clinical practice due to its diverse etiologies. [jneuro.com]

Etiology Clinical features Extorsion of the eye : inability to depress and adduct the eyeball simultaneously (the pupil shoots upward during attempted adduction of the eyeball) Diplopia ( double vision ) Mild esotropia Trigeminal nerve lesion (V) Etiology [amboss.com]

Epidemiology In 2007, the Moebius Syndrome Foundation estimated that there were at the time a total of approximately 2,000 cases of Moebius Syndrome worldwide [6]. [physio-pedia.com]

Maria alle Fonti” Medical Center, Salice Terme, Pavia, Italy d San Rossore Hospital, Pisa, Italy e Unit of Maxillo-Facial Surgery, Department of Health Sciences, San Paolo Hospital, University of Milan, Milan, Italy f Department of Biometry and Clinical Epidemiology [functionalneurology.com]

The relevant literature is reviewed and different hypotheses concerning the pathophysiological mechanisms of nerve damage are discussed. [ncbi.nlm.nih.gov]

This case strongly suggests that surgical intervention is effective for this pathophysiology. [surgicalneurologyint.com]

There is a scarcity of literature in recognizing HNPs following trauma and a lack of pathophysiological understanding to both a delayed presentation and to resolution versus persistence. [jcvjs.com]

Pathophysiology Facial nerve injury can be complete or partial. Generally, partial disruption of axonoplasmal flow reveals a greater chance of complete functional recovery. [emedicine.medscape.com]

Therefore, in order to prevent this complication, we must perform mask ventilation and direct laryngoscopy carefully. Head and neck manipulation should be gentle during anesthesia for shoulder surgery. [ncbi.nlm.nih.gov]

If a seizure occurs, appropriate intravenous antiepileptic drug (AED) treatment should be administered to prevent recurrent seizures [1]. [explainmedicine.com]

1. Thompson EO, Smoker WR. Hypoglossal nerve palsy: a segmental approach. Radiographics. 1994;14(5):939-958.
2. Boban M, Brinar VV, Habek M, Rados M. Isolated hypoglossal nerve palsy: a diagnostic challenge. Eur Neurol. 2007;58:177-181.
3. Loro WA, Owens B. Unilateral Hypoglossal Nerve Injury in a Collegiate Wrestler: A Case Report. J Athl Train. 2009;44(5):534-537.
4. Hui AC, Tsui IW, Chan DP. Hypoglossal nerve palsy. Hong Kong Med J. 2009;15(3):234.
5. Yasuda T, Togawa D, Hasegawa T, et al. Hypoglossal Nerve Palsy as a Complication of an Anterior Approach for Cervical Spine Surgery. Asian Spine J. 2015;9(2):295-298.
6. Al-Benna S. Right hypoglossal nerve paralysis after tracheal intubation for aesthetic breast surgery. Saudi J Anaesth. 2013;7(3):341-343.
7. Shah AC, Barnes C, Spiekerman CF, Bollag LA. Hypoglossal Nerve Palsy After Airway Management for General Anesthesia: An Analysis of 69 Patients. Anesth Analg. 2015;120(1):105-120.