Case Report Contralateral Glossoplegia in A Lower Pontine Infarction Bon D. Ku, MD, PhD,* Hak Young Rhee, MD, PhD,† and Sung Sang Yoon, MD, PhD† A 65-year old man developed sudden dysarthria, dysphagia, right-sided weakness, and sensory loss. The neurologic examination revealed left-sided tongue deviation caused by right glossoplegia. A magnetic resonance imaging scan revealed an elongated acute infarction from the left ventromedial portion of the lower pons extending to the dorsal pontine tegmentum area. The ipsilateral tongue deviation of the patient may result from interruption of the contralateral crossed corticohtpoglossal projection. This finding suggests that the possibility of the corticohypoglossal decussation may exist just above the pontomedullary junction, with individual variability. Key Words: Corticohypoglossal projection—hypoglossal nucleus—tongue deviation. Ó 2012 by National Stroke Association A 65-year-old hypertensive man suddenly developed vertigo, dysarthria, dysphagia, right-sided hemiparesis, and paraesthesia. The neurologic examination revealed that he was alert, fully oriented, and cooperative. There was no decline in language function. He was found to have hemiparesis, hemisensory loss, increased deep tendon reflex, and the Babinski sign on the right side. On cranial nerve examination, he was found to have unilateral lingual palsy. When he protruded his tongue to the midline, the tongue deviated to the left (Fig 1, A). The diffusion-weighted image of the brain, performed 1 day after symptom onset, revealed an elongated acute infarction in the ventromedial portion of the left From the *Departments of Neurology, Kwandong University College of Medicine, Goyang; and †KyungHee University School of Medicine, Seoul, Korea. Received March 24, 2011; revision received April 28, 2011; accepted May 13, 2011. Supported by a grant from the Korea Health 21 R&D Project, Ministry of Health, Welfare & Family Affairs, Republic of Korea (A050079). Address correspondence to Bon D. Ku, MD, PhD, Department of Neurology, Myongji Hospital, 697-24, Hwajung Dong Dukyang Gu Goyang Gyeong Gi, Republic of Korea. E-mail: neurodasan@paran. com. 1052-3057/$ - see front matter Ó 2012 by National Stroke Association doi:10.1016/j.jstrokecerebrovasdis.2011.05.015 pons extending to the distal dorsal pontine tegmentum (Fig 1, B). There were no other abnormalities in the cerebrum, brainstem, or cerebellum, and magnetic resonance angiographic studies were normal. Neither atrophy nor fasciculation was observed in the tongue, and there were no abnormalities on tongue electromyography. The neurologic deficits, including tongue deviation, gradually improved. Forty-five days poststroke, he had mild dysarthria, right-sided weakness, and paraesthesia without glossoplegia. Discussion Tongue deviation in unilateral stroke results from the asymmetrical supranuclear control of the hypoglossal nerve.1 The lesions of the corticohyopoglossal projection from the lower precentral gyrus to the decussation level result in tongue paralysis to the side of the hemiparesis.1,2 However there is a relative controversy on the exact decussation level of the corticohyopoglossal projection in the human brainstem.3,4 Supranuclear glossoplegia is not as uncommon as we previously thought. The reported incidence of the tongue deviation in acute ischemic stroke was 29%.1 However, with regard to supranuclear projections to the hypoglossal nucleus in the human brainstem, it is still unclear at what level they decussate over the midline to reach the contralateral nucleus. Urban et al3 showed that lesions of the ventral pontine base located close to the midline only impair Journal of Stroke and Cerebrovascular Diseases, Vol. 21, No. 8 (November), 2012: pp 905.e1-905.e3 905.e1 905.e2 B.D. KU ET AL. Figure 1. (A) The protruded tongue deviating to the left about 2.0 cm from the midline. (B) Diffusion-weighted imaging reveals an elongated acute infarction in the ventromedial portion of the left pons extending to the distal dorsal pontine tegmentum. (C) There is no evidence of acute infarction below lower pontine level including medulla in the DWI. the contralateral corticohypoglossal projections, while lesions extending to the lateral part of the basis pontis and dorsolateral lesions of the upper medulla near the pontine border affect the ipsilateral projections.3 They Figure 2. The possible corticohypoglossal decussation of the patient above pontomedullary junction. The gray ovals indicate the hypoglossal nucleus, the black line indicates the course of corticohypoglossal projection, and the black rectangle indicates infarction. suggested that the main decussation of the corticohypoglossal projection is located close to the pontomedullary junction.3 However, Chang and Cho4 reported a patient with medial medullary infarction with contralateral glossoplegia and suggested the possibility of the upper medullary level decussation of the corticohypoglossal projection.4 The lack of fasciculation and atrophic change of the tongue indicates that the patient’s glossoplegia is of the supranuclear type, even though the direction of tongue deviation is opposite to the usual supranuclear glossoplegia. In our patient, the possible explanation of the contralateral lingual palsy of the supranuclear type is as follows: The hypoglossal nuclei columns, which are located on either side of midline, extend from the caudalmost position on the medulla oblongata to the medullary–pontine junction.5 The decussation fiber of the corticohypoglossal projection may cross midline above the pontomedullary junction.3 As the previous study reported, the lesions of the ventral pontine base, located close to the midline, only impair the contralateral projections.4 So the left medial lower pontine infarction in our patient may have the possibility of the interruption contralateral crossed corticohtpoglossal projection to the left side hypoglossal neucleus (Fig 2). This interruption may cause left hypoglossal nerve palsy and result in left-sided tongue deviation. With regard to the corticohtpoglossal projections to the hypoglossal nuclei, they seem to have high individual variability. Although we are not aware of any reports CONTRALATERAL GLOSSOPLEGIA IN A LOWER PONTINE INFARCTION that have systematically studied the variability of the locations of these nuclei, in some individuals the corticohypoglossal projections may be decussated at the above pontomedullary junction. References 1. Umapathi T, Venketasubramanian N, Leck KJ, et al. Tongue deviation in acute ischaemic stroke: A study of supranuclear twelfth cranial nerve palsy in 300 stroke patients. Cerebrovasc Dis 2000;10:462-465. 905.e3 2. Kuypers HGJM. Corticobulbar connections to the pons and lower brain-stem in man. Brain 1958;81:364-388. 3. Urban PP, Hopf HC, Connemann B, et al. The course of cortico-hypoglossal projections in the human brainstem. Brain 1996;119:1031-1038. 4. Chang D, Cho SH. Medial medullary infarction with contralateral glossoplegia. J Neurol Neurosurg Psychiatry 2005;76:888. 5. Corfield DR, Murphy K, Josephs O, et al. Cortical and subcortical control of tongue movement in humans: a functional neuroimaging study using fMRI. J Appl Physiol 1999;86:1468-1477.