Hypertrophic olivary degeneration following trauma - a case report

Hypertrophic Olivary Degeneration and Holmes Tremor: Case Report and Review of the Literature

BACKGROUND

Hypertrophic olivary degeneration (HOD) is very rare type of degeneration that causes hypertrophy rather than atrophy. The classical presentation of HOD is palatal myoclonus. However, HOD may rarely present with Holmes tremor (HT). HT is unusual symptomatic tremor characterized by combination of rest and intention tremor. It has been reported in small case series, so far.

CASE DESCRIPTION

In this study, a man aged 62 years with HOD and HT spreading to the upper and lower extremities after pontine-midbrain hemorrhage due to cavernoma was presented.

CONCLUSIONS

Although pontine-midbrain hemorrhage may cause HT in the late period, HOD can be revealed on magnetic resonance imaging. Tract anatomy, especially the Guillain-Mollaret triangle, should be considered to explain the relationship between HT and HOD.

MRI findings of olivary degeneration after surgery for posterior fossa tumours in children: incidence, time course and correlation with tumour grading

PURPOSE

Olivary degeneration is due to many posterior cranial fossa (PCF) lesions affecting the dentato-rubro-olivary pathway, also known as Guillain-Mollaret triangle. Triangle damage results in hyperexcitation and consequently in hypertrophy of the inferior olivary nucleus (ION). The aim of our study was to evaluate the incidence of magnetic resonance (MR) imaging changes in the ION after surgery in a large cohort of paediatric patients and to determine their correlation with tumour grade.

MATERIALS AND METHODS

We retrospectively evaluated 58 patients treated surgically for PCF tumours who underwent MR imaging between 2007 and 2014, 1 week to 5 years after surgery. Histopathology revealed 29 medulloblastomas (WHO IV), 6 ependymomas (WHO II), 2 anaplastic ependymomas (WHO III) and 21 pilocytic astrocytomas (WHO I). ION MR imaging changes were correlated with surgery-to-MR interval and with tumour grading.

RESULTS

ION MR imaging changes were observed in 19/64 (33 %), and all consisted of T2 signal alterations, 15 bilateral and four unilateral, with dentate nucleus damage in all cases. Olivary enlargement was observed in few cases only (7/19). ION T2 hyperintensity was always present between 1 and 6 months after surgery with a trend to decrease, becoming faint after 1 year. The Fisher test demonstrated a significant (p = 0.005) correlation between ION MR imaging changes and high tumour grade.

CONCLUSIONS

Our results demonstrate that olivary degeneration, with or without hypertrophy, is a relatively frequent consequence of posterior fossa surgery, particularly in children treated for high-grade tumours. Knowledge of this condition can prevent misdiagnoses and unnecessary investigations.

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

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.