A Rare Variant of the Lateral Medullary Syndrome with Craniovertebral Junction and Vascular Anomalies
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.293463
Source of Support: None, Conflict of Interest: None
Lateral medullary syndrome (LMS) is an interesting neurological condition with excellent clinical teaching points. It commonly presents with loss of sensation on the ipsilateral face and contralateral body. Various other patterns of sensory involvement can occur. Facial weakness is not uncommon but infranuclear palsy is notably rare. We hereby present a case of LMS with the previously unreported combination of contralateral face and body sensory loss with ipsilateral infranuclear facial weakness. Interestingly, our patient with LMS also possessed craniovertebral (CV) junction anomalies. We noted that CV junction anomalies are reported to predispose to stroke and abnormalities of the posterior vasculature are commonly observed in these patients.,
A 21-year-old male construction worker presented with acute onset, two-day history of numbness of the right face and body, deviation of his mouth to the right, slurring of speech, difficulty in swallowing, and nasal regurgitation of liquids. He had no weakness, imbalance, vision and hearing issues, vertigo, tinnitus, or bowel and bladder complaints. He denied no fever, trauma, fall, dog bite, or recent vaccinations. Antenatal, birth, family, and past histories were noncontributory.
Examination revealed a short neck (height-neck ratio of 15) with notable scoliosis but with a normal range of movements and posterior hairline. Neurological exam was positive for loss of touch and pain sensations on the right face, deviation of mouth to right, left-sided loss of forehead wrinkling and lagophthalmos, deviation of uvula to the right, impaired gag reflex, left-sided Horner syndrome, and loss of pain, temperature, and crude touch on the right side of the body. The lesion was localized based on the above cranial nerve and sensory involvement to the left medulla. Initial causes considered were stroke due to embolus and vertebral artery dissection, and demyelinating disorders, given young age and acute onset.
A non-contrast CT brain was reported normal. An MRI Brain was pursued, which revealed an acute infarct of the left upper medulla at the junction with the lower pons [Figure 1].
MR angiography was performed which revealed a myriad of vascular abnormalities. Hypoplastic A1 segment of the right anterior cerebral artery (ACA) was noted with flow across the anterior communicating artery (AcommA). Bilateral vertebral arteries (VA) were observed to be low calibre and hypoplastic from their origin. Bilateral fetal posterior cerebral arteries (PCA) with thinned P1 segments and prominent posterior communicating artery (PcommA) were seen. BA, posterior inferior cerebellar (PICA) and superior cerebellar artery (SCA) were all hypoplastic and poorly visualized [Figure 2]. Most interestingly, prominent carotid-to-vertebrobasilar anastomoses were identified in the form of a right hyperplastic anterior choroidal artery (AchA) and a left persistent trigeminal artery (PTA) connecting the internal carotid arteries (ICA), respectively to the basilar arteries (BA).
Interestingly, further evaluation of craniovertebral (CV) junction revealed basilar invagination and occipital assimilation of the atlas as defined by Chamberlain line measurement [Figure 3].
A final diagnosis of young stroke (atypical LMS) with CV junction anomaly and anomalous posterior circulation with carotid-vertebral anastomoses was made. The patient was started on aspirin and atorvastatin. Nasogastric tube feeding was required due to prominent dysphagia. Complete blood counts, lipid profile, urinalysis, renal and liver function tests, EKG, and echocardiogram were normal. Bubble contrast echo did not reveal intracardiac defects. The patient was observed in the hospital and showed significant improvement with minimal residual facial palsy, sensory deficit, and dysphagia. He was discharged on aspirin and statin and is currently deficit free on follow up except for mild sensory impairment of the right body and limbs, pending further neurosurgical evaluation.
To our awareness, there are no previously reported cases of LMS presenting with ipsilateral infranuclear palsy and contralateral face-body-limb sensory loss. This provides excellent neuroanatomical teaching points [Figure 4]. The contralateral pain and temperature loss on the face occur in lateral medullary infarcts that extend medially to involve the ventral trigeminothalamic tract (VTT) relaying sensations from the contralateral face. Interestingly, painful trigeminal neuralgia is also noted to occur in LMS due to involvement of the central trigeminal pathways. The ipsilateral loss of facial sensation in classical LMS is not observed here due to possible sparing of the spinal trigeminal tract dorsolateral to the VTT. Involvement of the adjacent ascending spinothalamic tract explains contralateral body-limb sensory loss observed here. The lack of cerebellar involvement, vertigo, and tinnitus in our patient is possibly explained by atypical sparing of further dorsolaterally situated structures namely cerebellar peduncle, vestibular nuclei, and spinocerebellar tracts. Central facial palsy in LMS is reported to occur due to involvement of corticobulbar fibers that loop in the medulla before reaching the pontine facial nucleus. Infranuclear palsy is limited to a few case reports and is explained by the involvement of exiting facial nerve fascicles at caudal pons in infarcts extending to the pontomedullary junction. In our patient, these findings are strongly corroborated by the location of the infarct on MRI.
Although posterior circulation stroke is seen in young patients with CV junction anomalies, stroke as the presenting feature of CV anomaly is rarely observed., In our patient, a workup for stroke showed basilar invagination, occipital assimilation of the atlas, and a mixture of vascular anomalies which probably occurred at the fetal stages due to unidentified causes. Angiographic studies reveal a high prevalence of vertebral artery insufficiency in patients with CV junction anomalies. Our patient showed [Figure 2] bilateral VA hypoplasia with poor BA, PICA, and SCA flows. A fetal left PTA of Saltzmann type 2 variety was seen supplying the BA, characterised by hypoplastic P1 segment and P2 supply from PcommA (fetal PCA). The most common type 1 variant is associated with PCommA hypoplasia, which is not observed in our patient. The population incidence of PTA varies between 0.1–
0.7%, and is associated with a higher risk for aneurysm, hemorrhage, embolism, and trigeminal neuralgia. These complications were not observed. We hypothesize that thrombosis and local distal embolization due to compressive forces on the thinned-out VA by the bony anomalies at the CV junction could possibly be the mechanism of stroke in our patient. The severity of CV anomaly and scoliosis pointed towards a high possibility of shear-stress on the posterior vasculature. It is, therefore, reasonable to stress the importance of close evaluation of the CV junction and vasculature in posterior circulation strokes. Neurosurgical correction of the CV anomaly is hindered by the vulnerable vasculature in these cases. Elective surgery is planned in our patient after further angiographic assessment.
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The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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There are no conflicts of interest.
[Figure 1], [Figure 2], [Figure 3], [Figure 4]