A 40-year-old woman presented with 1-day history of sudden onset unsteadiness and swaying to the sides while walking. She was hypertensive on irregular medication. On examination, she had left internuclear ophthalmoplegia (INO) with normal convergence [Video 1]. She also had bilateral cerebellar signs (impaired past pointing, dysarthria, and not able to walk in tandem) [Video 1]. No motor weakness or sensory loss was observed. Superficial and deep tendon reflexes were normal.
This combination of signs was initially thought to be due to separate lesions at the brainstem and cerebellum. However, MRI brain [Figure 1] showed an infarct in the caudal midbrain affecting the left medial longitudinal fasciculus (MLF) and the decussation of the superior cerebellar peduncles (SCP). The clinical and radiological features are characteristic of Wernekinck commissure syndrome.
Figure 1.
MRI brain T2 FLAIR showing infarct in the caudal midbrain
Decussation of the SCPs was first described by Friedrich Christian Gregor Wernekinck and was named as the horseshoe-shaped commissure of Wernekinck by his student Franz Joseph Julius Wilbrand (father of Hermann Wilbrand of the Wilbrand knee).[1] The SCP carries crossing ascending dentatorubrothalamic and descending dentate-rubro-olivary tracts to the contralateral side.
Lesion of this commissure along with the MLF causes INO with bilateral appendicular cerebellar signs along with truncal ataxia and dysarthria. This combination of INO with cerebellar signs is known as Wernekinck commissure syndrome and was first described by Lhermitte.[2] Interruption of the descending dentate-rubro-olivary tract can lead to delayed palatal myoclonus with hypertrophy of the inferior olivary nucleus.[2]
Note: Only one paper spells the name as Wernekinck[1] while all others omit the 'c' (Wernekink).
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REFERENCES
- 1.Voogd J, van Baarsen K. The horseshoe-shaped commissure of Wernekinck or the decussation of the brachium conjunctivum methodological changes in the 1840s. Cerebellum. 2014;13:113–20. doi: 10.1007/s12311-013-0520-9. [DOI] [PubMed] [Google Scholar]
- 2.Zhou C, He Y, Chao Z, Zhu Y, Wang P, Wang X. Wernekink commissure syndrome secondary to bilateral caudal paramedian midbrain infarction presenting with a unique “Heart or V” appearance sign: Case report and review of the literature. Front Neurol. 2017;8:376. doi: 10.3389/fneur.2017.00376. [DOI] [PMC free article] [PubMed] [Google Scholar]
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