Vestibular imbalance associated with a lesion in the nucleus prepositus hypoglossi area

Background: The nucleus prepositus hypoglossi (NPH) is known to be a neural integrator of horizontal eye movements. Although the role of the human NPH is not well known, it may also function in postural balance, in view of its anatomic connections with the vestibular nuclei and vestibulocerebellum and of lesion studies in experimental animals. Objective: To show that the human NPH contributes to vestibular function in addition to eye movement control. Design: Case series. Setting: University hospital. Patients: Six patients with small and discrete brain-stem infarctions that predominantly involved the NPH-region. Main Outcome Measure: Findings on magnetic resonance images. Results: The NPH was affected at the lower pontine level in 2 patients and at the upper medullary level in 4. In addition to gaze-evoked nystagmus, all patients had vertigo, vomiting, and postural ataxia, suggesting vestibular dysfunction. The patients typically fell contralaterally or bilaterally to the lesion side. Conclusion: The NPH serves a vestibular function in addition to its oculomotor control function.