Bilateral hypertrophic olivary degeneration following surgical resection of a posterior fossa epidermoid cyst

Abstract

Hypertrophic olivary degeneration is a result of a primary lesion damaging the dento-rubro-olivary pathway. It is a transynaptic form of degeneration and is unique, causing hypertrophy rather than atrophy of the inferior olivary nucleus. We report a case of bilateral hypertrophic olivary degeneration following surgical excision of a posterior fossa epidermoid cyst and review the relevant literature.

Frequency of Bilateral Hypertrophic Olivary Degeneration in a Large Retrospective Cohort

“…Contralateral HOD is thought to occur when the lesion disrupts the superior cerebellar peduncle or dentate nucleus. Bilateral HOD is thought to occur when lesions involve both the red nucleus or the central tegmental tract (CTT) and the dentate nucleus or the superior cerebellar peduncle …”

“…A lesion occurring in this dentato‐rubro‐olivary pathway (DROP) can result in HOD (Fig ) . A variety of causative lesions have been described including infarction, toxic, trauma or surgery, tumor, vascular malformations or hemorrhage . Unilateral cases have been reported to significantly outnumber bilateral cases, perhaps due to the fact that previously reported cases of HOD in the literature have focused on identifying HOD secondary to a structural lesion in the DROP .…”

Collision in the inferior olive: hypertrophic olivary degeneration complicated by radiation necrosis in brainstem primitive neuroendocrine tumor

“…We postulate that the HOD was caused by surgical disruption of the central tegmental tract that connects the red nucleus and the inferior olive. Other investigators have also reported development of HOD after surgery [7,8]. RT may have played a contributory role, as HOD has been described after targeted radiosurgery [9], although a pure radiation effect is thought unlikely, as are direct effects on the triangle from the tumor itself or from chemotherapy.…”

Hypertrophic Olivary Degeneration after Gamma-knife Radiosurgery for Pontine Metastasis

“…[1][2][3][4][5][6][7] However, the incidence of these symptoms varies. 2,5,8 Some reports describe HOD occurring after surgical resection of a brain tumor, [5][6][7] but HOD is rarely caused simply by a tumor in the GuillainMollaret triangle. 8,9 We believe this case report represents theˆrst published description of HOD following GKRS for a brain tumor.…”