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Isolated acute bilateral hypoglossal nerve (CXII) paralysis is a very rare clinical condition which has been described in the context of traumatic mechanical injuries to the nerves.1 The two nuclei of CXII, located at the tegmentum of the medulla oblongata, are in close proximity and may be damaged at the same time.2 However, isolated bilateral CXII paralysis has not been described in cases of medullary infarction. We report a patient presenting with isolated complete tongue paralysis and a small ischaemic area in the medulla affecting both CXII nuclei exclusively.
A 49 year old woman with a history of primary biliary cirrhosis presented to the emergency room with acute dysarthria, swallowing difficulty, and inability to protrude her tongue. She was unable to eat, drink, or handle saliva. She denied vertigo, dizziness, nausea, unsteady gait, numbness, or weakness.
Examination showed that she was alert and responsive but was dysarthric and unable to initiate a swallow. Pupils were 3 mm in diameter, equal, and reactive to light and accommodation Extraocular movements were full. There was no ptosis and the corneal reflex was present bilaterally. Sensation was intact to light touch and pin prick. There was no spontaneous or gaze nystagmus, saccadic pursuit, or ocular dysmetria. Facial symmetry was noted, with no signs of weakness. The gag reflex was present with symmetric palatal elevation. Her tongue had limited protrusion and no side to side movement. The remainder of the cranial nerve examination was normal.
Neuromuscular strength was preserved. There were no sensory deficits to touch, pain, temperature, vibration, or position sense. Deep tendon reflexes were normal and there were no pathological reflexes. Coordination of the extremities was intact. Gait was not ataxic.
Clinical laboratory tests proving normal included an echocardiogram, chest x ray, repetitive nerve stimulation and single fibre electromyography, erythrocyte sedimentation rate, full blood count, serum electrolytes, fasting lipid profile, angiotensin converting enzyme, protein S, protein C, lupus anticoagulant, anticardiolipin antibodies (IgG and IgM), plasma homocysteine levels, C3 and C4 complement, anti-ENA (anti-Sm, SS-A/anti-Ro, SS-B/anti-La, and anti-RNP), antinuclear antibodies, antiacetylcholine antibodies, serum syphilis serology, and cerebrospinal fluid findings. Magnetic resonance imaging (MRI) showed a region of increased signal intensity on T2 weighted and fluid attenuated inversion recovery images, involving only the two CXII nuclei; no further lesions were observed (fig 1). Figure 2 is a schematic drawing of the lesion. Conventional cerebral angiography showed a narrow basilar artery as well as tortuosity of the vertebral artery at the cervical level. The patient required a nasogastric tube for feeding.
Aspirin 300 mg daily was initiated. Four days after the onset of symptoms, the patient began suffering from sustained paroxysmal hiccups. Chlorpromazine 75 mg daily and valproic acid 500 mg daily were then given orally for 10 days, but the hiccups continued. She was then given 5 mg of baclofen orally three times a day, and the hiccups abated within 48 hours. The baclofen was discontinued after one week of treatment, and the hiccups did not recur.
The condition of the patient improved within the following weeks. Two months after onset, she reported the return of some tongue mobility. She began to eat and drink without a nasogastric tube. On examination, her tongue had limited ability to protrude but there was some side to side movement. No tongue atrophy was observed. Five months later, she presented with acute diplopia and right facial weakness which lasted for 14 days. Examination showed a right lateral rectus nerve paralysis along with a right peripheral facial nerve paralysis. Further cranial MRI showed no new lesions apart from the previous evidence of brain stem ischaemia. The patient was then switched to warfarin.
A two year follow up examination showed that her tongue mobility had returned to normal. The tongue had full side to side motion and full protrusion. No further strokes occurred and she continues taking warfarin.
Medial medullary infarcts represents less than 0.5% of all cerebral infarcts.3,4 They may be unilateral or, rarely, bilateral. The clinical features of bilateral medial medullary infarctions are flaccid quadriplegia sparing the face, bilateral disturbance of deep sensation, weakness of the tongue, and respiratory failure.3,4 The case here reported broadens the spectrum of the medial medullary syndrome. The isolated bilateral CXII paralysis in our patient was the only manifestation of a bilateral medullary infarct. Tongue paralysis is caused either by involvement of the fibres of the hypoglossal nerve, which are located just lateral to the medial lemniscus and the pyramid, or by involvement of the nucleus.2 The CXII nucleus is placed in the dorsomedial medulla and depends on the territory of the anteromedial arteries, which, in addition, supply the medial portion of the pyramidal tract and its decussation, the medial lemniscus, and the medial longitudinal fasciculus. The anteromedial arteries usually arise from the anterior spinal artery to the caudal medulla and from the distal vertebral artery or proximal basilar artery to the rostral medulla.3,4
With regard to aetiology, the vertebrobasilar system was found to be hypoplastic. We feel that an anomalous branch of a vertebral artery supplied both sides of medial medullary area. Distal occlusion of this rostral branch at the level of the dorsal medulla resulted in a restricted bilateral CXII infarct. Our patient had a further vertebrobasilar stroke and was switched to warfarin. Patients with ischaemia in the territory of a hypoplastic vertebrobasilar system may be treated with either antiplatelet agents or warfarin.5 However, recurrent transient ischaemic attacks may be more common in patients given antiplatelet agents. In a recent series, for example, two of four patients with symptomatic vertebrobasilar hypoplasia who were initially treated with an antiplatelet agent developed recurrent transient ischaemic attacks. In contrast, none of the patients treated with warfarin had recurrent symptoms.5
In conclusion, this case shows that an isolated complete tongue paralysis can be produced by bilateral medullary infarction, a finding that broadens our understanding of the spectrum of medial medullary syndrome.
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