Inferior olivary hypertrophy is associated with a lower functional state after pontine hemorrhage

BACKGROUND: Inferior olivary hypertrophy (IOH) may develop after pontine hemorrhage and may become a pacemaker for symptomatic palatal tremor (SPT). However, there is no information available that elucidates how IOH may affect the functional outcome. The purpose of this study was to investigate how frequently IOH was associated with clinical manifestations of involuntary movements, including ocular myoclonus (OM) and SPT, and whether IOH influenced the functional outcome after pontine hemorrhage. METHODS: In 20 consecutive patients undergoing inpatient multidisciplinary rehabilitation after pontine hemorrhage, the location of lesions (tegmental vs. ventral) and the presence of IOH were examined by magnetic resonance imaging, and the functional outcome was assessed by means of Fugl-Meyer scale for neurological impairment and Functional Independence Measure for disability on admission and discharge. RESULTS: In 10 patients, IOH was detected, and the tegmentum was involved in 7 of the 10 patients. OM or SPT was present in 7 of these 10 patients. In the remaining 10 patients, IOH was not detected, and the tegmentum was involved only in 2 of these 10 patients. None of them had OM or SPT. The presence of IOH was associated with a lower functional status on admission and discharge. CONCLUSION: After pontine hemorrhage, IOH may be associated with tegmental lesions with OM or SPT and may impose a detrimental effect on the functional outcome.