Palatal Myoclonus, Ataxia, and Eight-and-a-Half Syndrome Secondary to a Hemorrhagic Cavernoma in the Dorsal Pons: A Video Case Report
Mario Yepez1, Andrew Welleford1, Padmaja Sudhakar1, Zain Guduru1
1Department of Neurology, University of Kentucky
Objective:
Illustrate the clinico-radiologic correlation of palatal tremor and eight-and-a-half syndrome following a pontine cavernoma hemorrhage and resection, highlighting the role of the Guillain-Mollaret triangle in delayed-onset palatal myoclonus.
Background:
We present a video case report of a 39-year-old woman with a family history of Cerebral Cavernous Malformations associated with CCM1 mutation, who was found to have several cavernomas located in the left parietal lobe and right dorsal pons. She experienced hemorrhage of the right pontine cavernoma complicated by edema, compression of the 4th ventricle, intractable nausea and vomiting, and left sided loss of sensation. She underwent surgical resection, after which the patient developed right abducens and right facial nerve palsies, and right internuclear ophthalmoplegia (INO). Three years post-resection the patient began noticing a clicking sound in her mouth at night.
Design/Methods:
Not applicable
Results:
The video shows the source of the patient's new symptom: delayed development of palatal myoclonus. Her examination also demonstrates limited adduction and abduction of the right eye with limited adduction and full abduction with associated nystagmus on left gaze consistent with right one-and-a-half syndrome; in combination with right CN VII palsy forming an eight-and-a-half syndrome. Additionally, she demonstrates left hemiataxia with ataxic gait. MRI images demonstrate a right pontine cavernoma with ipsilateral hypertrophic olivary degeneration due to lesion of the Guillan-Mollaret triangle.
Conclusions:
This case highlights the natural history and clinico-radiologic correlation of a dorsal pontine lesion leading to acute onset of eight-and-a-half syndrome with delayed development of palatal myoclonus. The extraocular movement deficits and facial weakness are likely arising from partial lesion to the ipsilateral sixth cranial nerve nucleus and adjacent facial nerve fibers. The palatal myoclonus and ataxia likely arises from a lesion in the ipsilateral central tegmental tract, part of the Guillain-Mollaret triangle, with subsequent hypertrophic olivary degeneration shown on the MRI.
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