406 - Ataxia secondary to anti-Hu Positive Paraneoplastic Syndrome in the setting of Mediastinal Pure Seminoma

Case Diagnosis: Ataxia secondary to anti-Hu Positive Paraneoplastic Syndrome in the setting of Mediastinal Pure Seminoma

Case Description: Patient is an 18 year old male w/ PMH of multiple mTBIs who presents with concerns of new onset, severe, progressive hearing loss, tremor, ataxia, peripheral neuropathy, hypophonia due to severe weakness in his vocal folds, dysphagia, and seizures. Patient who was an active participant in sports now required assistive devices for ambulation. Patient was concerned some of these new and progressive deficits, especially his ataxia, could be secondary to his mTBIs. Further workup was performed through a multidisciplinary approach. Patient was found to have positive ANNA1 for Anti-Hu (Titer 1:3840). CT chest showed nodule within the thymus w/ FNA suspicious for thymoma. Patient underwent radical thymectomy which demonstrated seminoma.

Discussions: Mediastinal Pure Seminoma is a rare disease and likely to be cured with surgical removal. Patient showed no evidence of tumor elsewhere on workup. Patient was additionally diagnosed w/ Rhomboencephalitis with cochlear involvement, secondary to ANNA1 antibody and was treated w/ high dose steroids w/ some symptom improvement. Patient was additionally started on IVIG q3weeks which helps with all symptoms. Patient continues to follow with a multidisciplinary team and participates in PT/OT/SLP.

Conclusions: Traumatic brain injuries can be life altering events for patients that affect their every day lives. However, once the injury occurs, they are not expected to significantly decline due to these injuries, especially in the setting of mild TBI. When presented with a patient who has new, progressive symptoms, especially several years out from their initial onset, it is important to work it up further. Mediastinal Pure Seminoma is not a typical diagnosis for a PM&R clinic, but one that still needs to be on the differential for a patient that presents similarly.