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.

Purely Endoscopic Retrosigmoid Approach for Excision of a Large Multicystic Hypoglossal Schwannoma.

Hypoglossal schwannomas are rare tumors that account for 1%-7% of all nonvestibular intracranial schwannomas. They commonly affect middle-aged females.1 They can be completely intracranial (type A), intracranial/extracranial (type B), or completely extracranial (type C).2 Presenting symptoms include hypoglossal nerve dysfunction, additional lower cranial neuropathies and, rarely, increased intracranial pressure. Patients with the rare extracranial tumors most commonly present with an asymptomatic mass in the neck or submandibular region.3 Treatment options include observation in small asymptomatic tumors and surgical excision in large tumors with mass effect. In tumors that require treatment and are within the size range, radiosurgery should be considered.1 In this operative Video 1, the patient is a 45-year-old woman who presented with a 1-year history of progressive headaches, right-sided retroauricular pain, unsteady gait, hoarseness of voice, and dysphagia. Neurologic examination revealed right cranial nerves IX to XII palsies, pyramidal manifestations, and right cerebellar ataxia. Imaging findings were consistent with large multicystic hypoglossal schwannoma. A purely endoscopic retrosigmoid approach was performed for excision of the lesion. A 4K rigid endoscope offers a highly illuminated and extremely detailed views of the tumor and the anatomic structures within the surgical field, adding greatly to the safety of surgery. Furthermore, the panoramic view and large depth of focus of the endoscope result in greater ease of orientation within the surgical field with significant reduction of the number of times the viewing angle needs to be changed during the procedure.

Isolated Hypoglossal Nerve Palsy as an Early Symptom of a Granular Cell Tumor.

BACKGROUND: Hypoglossal nerve palsy (HNP) is rather common as a neurological disease. However, as an isolated nerve palsy it is an exceedingly rare phenomenon and points at local pathologies along the peripheral course of the nerve. In this communication we report a granular cell tumor (GCT) arising in the submandibular segment of the hypoglossal nerve. CASE-REPORT: Spontaneous isolated HNP was recognized in a female patient. First line MR-imaging identified a clivus-chordoma. However, involvement of the hypoglossal nerve was highly unlikely according to MR-findings. Finally, ultrasonographic investigation revealed a small submandibular mass which, at histological examination, turned out to be a granular cell tumor arising within the hypoglossal nerve. CONCLUSIONS: This is the report of an extremely rare GCT originating within the 12th cranial nerve. The case illustrates that isolated motoric cranial nerve palsy may result from this rare tumor entity. This report also points out the diagnostic value of a simple ultrasonographic investigation to depict pathologic lesions of the submandibular space.

Schwannoma of the descending loop of the hypoglossal nerve: case report.

Schwannomas of the descending loop of the hypoglossal nerve are very rare. Existing literature of the schwannoma of the descending loop of the hypoglossal nerve is limited to two previously reported case. They are slow-growing tumors that may masquerade a carotid body tumor. We herein described a rare case of schwannoma of the descending loop of the hypoglossal nerve in the s right latero-cervical region with diagnostic imaging and histopathological findings. A 37-years-old woman has had a palpable firm, mobile mass in the right latero-cervical region, of imaging, MR images showed homogeneous hypointensity on T1-weighted imaging (T1-WI), heterogeneous hyperintensity on T2-WI, and heterogeneous enhancement on contrast-enhanced T1-WI. Diagnostic imaging using computed tomography (CT) and magnetic resonance imaging (MRI) was suspected of Chemodectoma or neurogenic tumor. At operation, a 4 cm mass arising from the descending loop of the hypoglossal nerve of was resected en bloc with the loop itself; Final diagnosis was confirmed on the basis of histopathological finding and intraoperative findings. Postoperative course was uneventful and the patient is free from disease recurrence at tree-year follow-up. En bloc resection remains the real curative treatment of Schwannomas, ensuring unlimited freedom from disease, although causing functional impairment which may be significant. Nonetheless recurrence should be prevented as, besides requiring reintervention, it may harbor a malignant evolution towards sarcoma. Schwannomas of the descending loop of the hypoglossal nerve may masquerade a chemodectoma of the carotid bifurcation and can be curatively resected without any functional impairment. This case confirmed the differential diagnosis on the basis of the intraoperative finding that the tumor was continuous with the hypoglossal nerve.

Imaging Features of isolated hypoglossal nerve palsy.

The hypoglossal nerve gives motor innervation to the intrinsic and extrinsic muscles of the tongue. Pathology of this nerve affects the balanced action of the genioglossus muscle causing tongue deviation toward the weak side. Clinically, hypoglossal nerve palsy manifests with difficulty chewing, swallowing and with dysarthric speech herein, we review the anatomy of the hypoglossal nerve as well as common and infrequent lesions that can affect this nerve along its course.

Isolated hypoglossal nerve palsy due to a jugular foramen schwannoma.

Introduction - Although the involvement of the hypoglossal nerve together with other cranial nerves is common in several pathological conditions of the brain, particularly the brainstem, isolated hypoglossal nerve palsy is a rare condition and a diagnostic challenge. Case presentation - The presented patient arrived to the hospital with a history of slurred speech and an uncomfortable sensation on his tongue. Neurological examination showed left-sided hemiatrophy of the tongue with fasciculations and deviation towards the left side during protrusion. Based on the clinical and MRI findings, a diagnosis of hypoglossal nerve schwannoma was made. Discussion - Hypoglossal nerve palsy may arise from multiple causes such as trauma, infections, neoplasms, and endocrine, autoimmune and vascular pathologies. In our case, the isolated involvement of the hypoglossal nerve was at the skull base segment, where the damage to the hypoglossal nerve may occur mostly due to metastasis, nasopharyngeal carcinomas, nerve sheath tumors and glomus tumors. Conclusion - Because of the complexity of the region's anatomy, the patient diagnosed with hypoglossal nerve schwannoma was referred for gamma knife radiosurgery.

The intracanalicular segment of the hypoglossal nerve: An anatomical study using magnetic resonance imaging.

Few studies have documented the morphology of the intracanalicular segment of the hypoglossal nerve (CSHN). Therefore, the aim of this study was to characterize the CSHN using magnetic resonance imaging (MRI). In total, 95 patients underwent thin-sliced, contrast MRI. The axial and coronal images were used for analysis. The CSHNs were bilaterally identified in 97% and 94% of the 95 patients on the axial and serial coronal images, respectively. On axial images, length of the hypoglossal canal was measured as 8.2 ±â€¯1.66 mm on the right and 8.4 ±â€¯1.71 mm on the left. The CSHN was delineated as a slightly tortuous, linear structure with variable length. The CSHN course in the hypoglossal canal could be classified into the ventral, central, and ventrodorsal types, with the ventral type most predominant and found in 65% on the right side and 43% on the left. The angle formed by the CSHN and perpendicular line was highly variable. On serial coronal images, the CSHN course in the hypoglossal canal was also variable and could be found in the any part of the canal. The CSHN is a distinct structure characterized by morphological variability, which can influence the type of hypoglossal neuropathy arising from the CSHN.

Atlantooccipital Synovial Cyst with Isolated Hypoglossal Nerve Palsy: Case Report of Nonfusion Surgical Approach and Review of Literature.

BACKGROUND: Isolated hypoglossal nerve palsy caused by an atlantooccipital synovial cyst is a rare lesion, with fewer than 5 cases reported in the literature. CASE DESCRIPTION: Our patient presented with acute hypoglossal nerve dysfunction. Our differential included neoplasm, trauma, stroke, multiple sclerosis, or other inflammatory/infectious etiology. Imaging revealed a peripherally enhancing, extradural focus in the left premedullary cistern, most likely consistent with a synovial cyst. CONCLUSIONS: A left suboccipital craniectomy was performed in the region of the left hypoglossal canal, in which a cystic structure was noted at the occipital condyle and C1 vertebral junction. The nerve was adequately decompressed via aspiration of the cyst. Postoperatively, the patient substantially improved. Although rare, synovial cysts must be included in the differential diagnosis of atlantooccipital lesions.

Hypoglossal canal schwannoma causing isolated left 12th cranial nerve palsy.

A 40-year-old woman presented with insidious onset, gradually progressive dysarthria and inability to manoeuvre bolus of food in her mouth while eating. The duration of her symptoms was 3 months. On evaluation, the left half of her tongue was wasted. The tongue deviated to the left on protrusion. There were no clinical features suggestive of involvement of the ipsilateral 9th, 10th or 11th cranial nerves. MRI of the brain showed a large, fusiform lesion in the left hypoglossal canal, extending into the jugular canal. The lesion was surgically excised and found to be a schwannoma.

Single-stage total resection of giant dumbbell-shaped hypoglossal schwannoma: a case report.

Extensive large dumbbell-shaped hypoglossal schwannoma is extremely rare, and total resection is nearly impossible. We present a case of a 61-year-old male with a giant-size hypoglossal schwannoma with moderate tongue atrophy. The tumor extended from the enlarged hypoglossal canal to the brainstem intradurally and the high cervical region extradurally. Through the extreme lateral infrajugular transcondylar (ELITE) skull base approach, the tumor was totally removed in a single-stage operation. Single-stage total resection is feasible by an experienced skull base team utilizing transcondylar skull base techniques and high cervical dissection.

Malignant peripheral nerve sheath tumor of the tongue with an unusual pattern of recurrence.

Malignant peripheral nerve sheath tumor (MPNST) of oral cavity is an extremely uncommon malignancy. Less than 15 cases have been reported since 1973 though none of them describes a distant metastasis. We present a rare case of MPNST of the tongue who presented with features of hypoglossal nerve palsy. Incisional biopsy showed a malignant spindle cell tumor in the sub-epithelial connective tissue. The tumor cells were immune-positive for S-100. He underwent surgery followed by adjuvant chemo-radiation. Later the disease recurred in the form of isolated pelvic bone metastasis. Palliative chemotherapy was offered to him. With this case report we intend to refer to such unusual presentation and pattern of recurrence in a MPNST of tongue.

Ganglioneuromas involving the hypoglossal nerve and the vagus nerve in a child: Surgical difficulties.

Ganglioneuromas are benign tumors that arise from the Schwann cells of the autonomic nervous system. They are usually seen in the posterior mediastinum and the paraspinal retroperitoneum in relation to the sympathetic chain. In the head and neck, they are usually related to the cervical sympathetic ganglia or to the ganglion nodosum of the vagus nerve or the hypoglossal nerve. We describe what we believe is the first reported case of multiple ganglioneuromas of the parapharyngeal space in which two separate cranial nerves were involved. The patient was a 10-year-old girl who presented with a 2-year history of a painless and slowly progressive swelling on the left side of her neck and a 1-year history hoarseness. She had no history of relevant trauma or surgery. Intraoperatively, we found two tumors in the left parapharyngeal space-one that had arisen from the hypoglossal nerve and the other from the vagus nerve. Both ganglioneuromas were surgically removed, but the affected nerves had to be sacrificed. Postoperatively, the patient exhibited hypoglossal nerve and vocal fold palsy, but she was asymptomatic. In addition to the case description, we discuss the difficulties we faced during surgical excision.

Spontaneous regression of a cystic hypoglossal schwannoma causing unilateral tongue atrophy.

A 60-year-old lady presented with intermittent headaches. Examination revealed striking marked unilateral tongue atrophy. Magnetic resonance imaging (MRI) revealed a cystic lesion in the hypoglossal canal and a provisional diagnosis of cystic hypoglossal schwannoma made. Annual surveillance scans showed stable appearances but surprisingly at 3 years they showed a significant reduction in the size of the lesion. Most patients with hypoglossal schwannomas present with ipsilateral hypoglossal nerve palsy; careful cranial nerve examination is vital in diagnosing such rare lesions. Little is known of their natural history, with most lesions undergoing surgery. This case highlights spontaneous regression following non-operative management.

A late recognition of tapia syndrome: a case report and literature review.

Tapia syndrome is characterized by concurrent paralysis of the recurrent laryngeal and hypoglossal nerves. The mechanism is associated with airway manipulation in 70% of patients and is attributed to compression or stretching of these nerves. Diagnosis is based on recognition of the concurrent paralyses and investigations to exclude central or vascular causes. Treatment is supportive, with emphasis on empiric corticosteroids and dysphagia therapy. Recovery is excellent in 30% of patients, incomplete in 39% of patients, and none in over 26% of patients. A case of a 48-year-old woman is described, who was diagnosed with Tapia syndrome 3 years after the suspected injury.

Acute brainstem compression by intratumoral hemorrhages in an intracranial hypoglossal schwannoma.

A 77-year-old female in the hospital was found tachycardic and hypothermic by a nurse, and the patient's respiration subsequently ceased. Forensic autopsy revealed an intracranial cystic tumor that would have compressed the brainstem. On microscopic examination, the tumor was diagnosed as an Antoni A schwannoma growth, and recent multiple intratumoral hemorrhages in the intracranial schwannoma were observed, suggesting the sudden enlargement of the intracranial schwannoma due to intratumoral hemorrhaging. Accordingly, we diagnosed the cause of death as brainstem compression induced by the intratumoral hemorrhaging in the intracranial schwannoma. Meanwhile, a rhinopharyngeal tumor was also detected by the autopsy, which was compatible with an antemortem diagnosis of a dumbbell-shaped hypoglossal schwannoma.

Delayed hypoglossal nerve palsy following unnoticed occipital condyle fracture.

Occipital condylar fractures (OCFs) are rare and difficult to diagnose. The routine use of computed tomography (CT) scan in traumatology has however now made their diagnosis easier, with an estimated frequency of 4 to 19% of craniospinal traumatized patients and 0.4 to 0.7% of all severe traumatized patients in emergencies. This paper describes a patient who was not diagnosed with OCF during his first hospitalization after a road accident. However, 15 days later a left sided hypoglossal nerve palsy occurred. In this case report, we underline that an examination of the cranial nerve is a quick and easy procedure to screen each head trauma patient for occipital foramen fractures. Also, careful attention must be paid to X-Rays, CT scans and magnetic resonance imaging of the craniocervical junction.