Acta Neurologica Belgica https://doi.org/10.1007/s13760-020-01493-1 NEURO-IMAGES Isolated cortical lingual palsy: a slip of the tongue Jaffar Vali Sayyed1 · K. P. Divya1 · Ajith Cherian1 · Naveen Kumar Paramasivan1 · S. Krishna1 Received: 6 August 2020 / Accepted: 4 September 2020 © Belgian Neurological Society 2020 Keywords Genioglossus · Corticobulbar fibres · Motor homunculus · Frontal operculum · Sylvian bank · Dysarthria A 69 year old man had sudden onset isolated dysarthria, without dysphagia, facial or extremity weakness, ataxia or sensory symptoms. He had no vascular risk factors. His past history was significant for severe aortic regurgitation for which he underwent bioprosthetic valve replacement a decade ago. On examination, he had leftward tongue deviation on protrusion (Fig. 1a). Rapid wiggling of the tongue was clumsy. On enunciation, the linguals were affected while the labials and gutturals were better preserved. No other cranial nerve palsy or long tract signs were seen. His sensory system examination, cerebellar assessment including tandem gait were normal. Workup revealed a small infarct in the right motor strip frontal operculum corresponding to lingual representation area (Fig. 1b–e). His etiological workup showed normal intracranial and extracranial blood vessels on magnetic resonance (MR) time of flight (TOF) images. His echocardiography showed structurally normal heart without any clot. Electrocardiogram and 24-h Holter monitoring was normal. Considering the history of previous valve replacement surgery, distal cortical location and small infarct size, cardio embolic phenomenon was considered as the most likely aetiology for his stroke. He was initiated on speech rehabilitation, anticoagulants and on 1-month follow-up, there were no further events and his speech had improved. Supranuclear localization for an isolated lingual weakness is rare. For voluntary movements, tongue receives corticobulbar fibres from both hemispheres except genioglossus muscle, which receives fibres only from contralateral hemisphere [1]. The action of healthy genioglossus is well appreciated on tongue protrusion whereupon it will push the tongue towards the side of unilateral weakness regardless of whether it is upper or lower motor neuron in origin (Table 1). In a series of 300 ischemic stroke patients with facial/brachial paresis or hemiparesis, deviation of tongue was reported in 29% [2]. In a case series of isolated dysarthria as a major clinical manifestation, which attempted to explain the clinico-anatomical correlation between lingual palsy and stroke, small infarcts located lateral to the precentral hand knob area along the motor strip, similar to ours, were identified [3]. Five among those six patients had artery-to-artery embolic phenomenon from proximal vessels, as an aetiology of stroke [3]. All case series [2, 3] and individual case reports [4] so far had been associated with facial or distal upper extremity weakness or dysphagia. Our case is unique in that the patient had isolated tongue weakness. Here imaging showed infarct exactly in the location as described by Penfield and Rasmussen on motor homunculus [5] (Fig. 1f). This case highlights the importance of aetiological consideration of stroke in such acute presentation * Ajith Cherian drajithcherian@yahoo.com 1 Department of Neurology, Sree Chitra Tirunal Institute of Medical Sciences and Technology, Kerala 695011, India 13 Vol.:(0123456789) Acta Neurologica Belgica Fig. 1  Isolated cortical lingual palsy due to infarct in the right frontal Sylvian bank. a Deviation of the patient’s tongue to left on protrusion indicating weakness of left genioglossus muscle. b Axial magnetic resonance (MR) diffusion-weighted image (DWI) shows hyperintensity (HI) in the right motor strip over frontal operculum (yellow arrow) with low apparent diffusion coefficient (ADC) values Table 1  Clinical differentiation of UMN and LMN unilateral lingual weakness Differentiating features (c yellow arrow head) corresponding to lingual representation area on motor homunculus suggestive of an acute infarct. d Axial fluid-attenuated inversion recovery MR image shows HI (white arrow) in the same area. e Sagittal T2-weighted MR image shows HI dorsolaterally (white arrow head) in the frontal Sylvian bank, just superior to Sylvian fissure. f Representative image of tongue area in the brain UMN Dysarthriab and difficulty in manipulating food inside mouth Deviation on protrusion Ipsilateral to side of weakness Ipsilateral to side of weakness Inspection Hemiatrophy may not be evident Early hemiatrophy, furrowing, fasciculations Palpation of affected half Spastic feel Flaccid feel Clinical presentation Dysarthriaa UMN upper motor neuron, LMN lower motor neuron a 13 LMN Spastic and bflaccid dysarthria may be evident only in bilateral weakness Acta Neurologica Belgica and the relevance of pertinent clinico-anatomical correlation, and confirmation by appropriate imaging for such a rare isolated clinical sign in neurology. Acknowledgements We acknowledge Dr Aswin R.M, Senior Resident in Cardiology, Government Medical College, Thiruvananthapuram, for his help and dedication in developing the schematic diagram for this paper. Funding The authors report no sources of funding. Compliance with ethical standards Conflict of interest There are no conflicts of interest. Ethical approval Not applicable. References 1. Brazis PW, Joseph C, José B (2011) Localization in clinical neurology. Wolters Kluwer Health/Lippincott Williams and Wilkins, Philadelphia 2. Umapathi T, Venketasubramanian N, Leck KJ et al (2000) Tongue deviation in acute ischaemic stroke: a study of supranuclear twelfth cranial nerve palsy in 300 stroke patients. Cerebrovasc Dis 10:462–465 3. Kim JS, Kwon SU, Lee TG (2003) Pure dysarthria due to small cortical stroke. Neurology 60:1178–1180 4. Yoon SS, Park KC (2007) Neurological picture. Glossoplegia in a small cortical infarction. J Neurol Neurosurg Psychiatry 78(12):1372 5. Schott GD (1993) Penfield’s homunculus: a note on cerebral cartography. J Neurol Neurosurg Psychiatry 56(4):329–333 Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Informed consent Informed consent has been obtained from the patient. 13