We describe a case of a 40-year-old white man with a history of transient idiopathic thrombocytopenia. He had no regular medication and worked as a lifeguard. His cholesterol levels were slightly elevated and he smoked 7 cigarillos a day. He did not have a history of obvious head or neck trauma but used to practice martial arts. In his family history, his mother had a cerebral infarction in her 60s. Four days before admission to our emergency room he realized he could not move his tongue to the

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... left side while chewing bread. He visited his primary care physician, who suspected angioedema and prescribed him prednisolone. The medication did not alleviate the symptoms and he gradually developed dysarthria and slight subjective difficulty swallowing food because of difficulty moving his tongue. A few days later the patient went again to see the same physician. He was then sent to a tertiary care unit where an ENT specialist examined the patient and performed endoscopy of the nose, pharynx, and larynx. No peripheral reason for the symptoms was found and he was referred to the neurologist. During clinical examination, the patient had difficulty moving his tongue to the left on protrusion, mild atrophy on the left side of the tongue, and slight dysarthria. A hypoglossal nerve lesion was suspected. He also had subjective feelings of dysphagia. The neurological examination was otherwise normal. He had no cervical lymphadenopathy or fasciculations of the tongue. MRI of the brain showed old infarctions in the right cerebellum. The brain stem, basal ganglia, liquor spaces, and gray matter were normal. There was no mechanical compression found of the hypoglossal nerve in the brain MRI. The chest radiograph was normal. The laboratory tests including blood count, routine coagulation markers, electrolytes, and creatinine were normal. Thereafter, a MR angiography was performed. What do you expect to be the finding? Answer MR angiography of the neck (Figure) showed dolichoectasia of the left internal carotid artery near the hypoglossal canal, which was a sequela of an older dissection according to the neuroradiologist. This 9-mm dilatation (compared with 4 mm of the normal vessel wall) could have caused hypoglossal nerve compression and the symptoms. The slight dysarthria and dysphagia were caused by impaired motor function of the tongue. According to our written institutional guidelines, we start warfarin in patients with acute carotid dissections; however, because of the chronic nature of the dissection in this case, warfarin was not started. Of note, because of the old cerebellar infarcts, cardiologist was consulted and no source of cardiogenic emboli was found on transesophageal echocardiography. Patent foramen ovale was not detected. A 48-hour ECG was normal. No thrombophilia was detected. Routine secondary preventive medications were prescribed, including aspirin, dipyridamole, simvastatin, and enalapril. A speech therapist checked for swallowing disturbances. According to the report the patient did not actually have dysphagia, but difficulties eating as a result of impaired movements of the tongue. The dysarthria almost completely resolved during the hospitalization. He was discharged with a recommendation to avoid sudden movements of the head and neck and to quit smoking. A follow-up visit was appointed. Discussion Solitary hypoglossal nerve (cranial nerve XII) palsy is relatively uncommon. The 12th cranial nerve emerges from the medulla between the ventrolateral sulcus, the olive, and the pyramids and exits the cranium through the hypoglossal foramen in the posterior cranial fossa. It passes downward near the inferior ganglion of the vagus to lie between the internal carotid artery and the internal jugular vein. The nerve then courses laterally to the bifurcation of the common carotid artery and loops above the hyoid bone before going ventrally to supply the muscles of the tongue. 1 The hypoglossal nerve is purely motor. It innervates the genioglossus, hyoglossus, styloglossus (extrinsic muscles), and the intrinsic muscles of the tongue, as well as the lower hyoid group of muscles by ansa cervicalis. The genioglossus muscle forms the main bulk of the tongue. The hypoglossus muscle is a thin, flat, quadrilateral muscle and the styloglossus muscle interdigitates with the hyoglossus muscle. The extrinsic palatoglossus muscle is the only tongue muscle, which is innervated by the vagus nerve.