Hypoglossal palsy and coeliac disease: an uncommon presentation for a common disease?

The hypoglossal nerve is responsible for motor innervation to the intrinsic and extrinsic muscles of the tongue. Nerve nuclei are located in paramedian position in the medulla oblongata from which, anteriorly, the rootlets exit and merge into hypoglossal canal. Emerging from skull base, the nerve passes through nasopharyngeal space near to the internal carotid artery and internal jugular vein; at hyoid bone level, it curves anteriorly and enters the muscle of the tongue. Knowing the anatomy of hypoglossal nerve is fundamental to understand the symptoms and analytically examine the numerous and different pathologic conditions causing nerve dysfunction. Usually tongue weakness is a part of more complex clinical picture: intramedullary lesions generally involve adjacent nuclei or tracts, while peripheral lesions involve other cranial nerves. Instead, isolated hypoglossal nerve palsy is a rare condition. In the most large series on the topic [1], among 100 patients twelve-nerve paralysis was prominent in only 5 cases. As regard etiology, different causes are known: tumors, trauma, carotid artery dissection, infection, multiple sclerosis, dural arteriovenous fistula, Chiari malformation, stroke, surgical and anaesthesiological procedures, kinking of the vertebral artery, radiotherapy [1]. In the patient described here, none of these causes were identified despite of the extensive laboratory and radiological investigations. We then classified this case idiopathic IHP and reviewed the literature as summarized in Table 1. To our knowledge, this is the first report of a possible association between IHP and CD. However, we believe that this condition may be more frequent than is thought. Notably, indeed, in none of the cases above listed and classified as idiopathic IHP, screening tests for gluten sensitivity were made. Neurological complications in CD are well-known. Peripheral neuropathy has been found in up to 49% of CD patients. The most common presentation is chronic distal, symmetric, predominantly sensory neuropathy even if other conditions have also been reported such as motor neuropathy, mononeuritis multiplex, Guillain–Barré-like syndrome, autonomic neuropathy. The involvement of cranial nerves has been found by Jacob et al. [3] in two cases of gluten sensitivity presenting as neuromyelitis optica. Interestingly, like in our report, both patients showed a significant clinical improvement and reduction of TTG and AGA following steroid treatment and the introduction of a gluten free diet. The pathogenesis of neuronal damage in CD is still unclear. Nutritional deficiencies secondary to malabsorption may contribute to the development of neurological deficits, but do not fully explain all the cases.Immunemechanisms have been also proposed and antiganglioside antibodies were found in CD patients with neuropathy. These antibodies recognize various epitopes in the peripheral nervous system and can be associated with autoimmune neuropathies (e.g. Miller–Fisher syndrome, multifocal motor neuropathy). Our patient showed increase in titer of anti-GM1 IgG. The hypothesis of Hadjivassiliou et al. [4] is that anti-transglutaminase antibodies, interacting with transglutaminase present in arterial wall, cause perivascular inflammation and damage in blood–nerve barrier. So, antiganglioside antibodies, induced in gut from the interaction between gliadin and ganglioside-rich intestinal brush border membrane, can cross the barrier and, binding neural antigens, produce dysfunction. Accordingly, in our patient the left hypoglossossal nerve appeared swollen and hyperintense at MRI with homogeneous gadolinium-enhancement indicating an active state of inflammation. In summary, we reported an unusual presentation of a previously unrecognized CD in an adult patient with acute onset of unilateral IHP that fully recovered with GFD and prednisone in few months. Surely, a single report is not enough to demonstrate with certainty the casual link between these conditions and more specifically designed studies are needed to clarify the nature of this presumable association. However, in consideration of the high frequency in general population of CD, an easily treatable disorder, we suggest to add CD serological screening to diagnostic panel for IHP.