Wernekink commissure syndrome

The Wernekink commissure syndrome (sometimes spelled Wernekinck) is a rare brainstem syndrome caused by lesions (usually infarcts) involving the decussation of the superior cerebellar peduncles (Wernekink commissure) at the caudal midbrain.

Clinical presentation

The syndrome is characterized by bilateral cerebellar dysfunction . This can manifest as gait and truncal ataxia, dysmetria on finger-nose-finger and heel-knee-shin tests, and dysdiadochokinesis. In addition, marked dysarthria is a consistent finding . Variable eye movement disorders and Holmes tremor are also described .

Midbrain lesions may involve the nearby medial longitudinal fasciculus, resulting in internuclear ophthalmoplegia . In some patients, involvement of the dentatorubral fibers, part of the triangle of Guillain and Mollaret, can manifest as delayed onset palatal tremor/myoclonus .

Pathology

The Wernekink commissure is supplied by inferior paramedian mesencephalic arteries, which are a subset of interpeduncular fossa perforating branches that may arise from the tip of the basilar artery, superior cerebellar artery, and/or P1 segment of the posterior cerebral artery . In a minority of cases, bilateral inferior paramedian mesencephalic arteries can be derived from a common trunk .

Radiographic features

MRI

An acute infarct of the Wernekink commissure appears as a hyperintensity on DWI in the caudal paramedian midbrain, ventral to the cerebral aqueduct . The lesion on DWI or FLAIR may be round, oval, heart, or V-shaped . Most cases are unilateral but some infarcts cross midline .

Because the lesion disrupts the triangle of Guillain and Mollaret, follow-up MRI may show hypertrophic olivary degeneration .

History and etymology

The disorder was first reported in 1958 by Lhermitte .

The commissure is named after Friedrich Christian Gregor Wernekinck (1798-1839), a German minerologist and anatomist . His pupil, Franz Joseph Julius Wilbrand (1811-1894), attributed the discovery of the commissure to Wernekinck and named it the horseshoe-shaped commissure of Wernekinck (commissura hipposideroformis Wernekincki).

Differential diagnosis

The normal fibers of the Wernekink commissure appear slightly hyperintense on DWI compared to surrounding brainstem in some people. Thus, caution is warranted so as to not over-call infarction when the area is actually normal.