Surgically treated intradural spinal manifestation of hereditary amyloidogenic transthyretin amyloidosis - A case report and scoping review of the literature.

Introduction: Hereditary transthyretin amyloidosis (ATTRv) is an autosomal-dominant disorder, where a TTR mutations lead to amyloid fibril deposits in tissues and consecutively alter organ function. ATTRv is a multisystemic disorder with a heterogeneous clinical presentation. Spinal leptomeningeal depositions are described only scarcely in the literature. Research question: We present a rare case of surgically treated intradural, extra-medullary amyloidosis with respective clinical, diagnostic and surgical features to raise awareness of this rare entity. Material and methods: Clinical, radiological and operative characteristics were retrieved from the electronical patient management system. Additionally, a scoping literature review on leptomeningeal spinal manifestations of ATTRv was performed. Results: A 45-year-old man with a known ATTRv presented with gait disturbance and paresis of the lower extremities. He had been treated with the siRNA therapeutical Patisiran for 13 months under which his symptoms worsened. An MRI of the spine revealed spinal cord compression with myelopathy at the level of T2 with anterior dislocation of the spinal cord due to an intradural, extramedullary lesion. A laminectomy and opening of the dura with a complete resection of the lesion was performed. The histological examination of the biopsy showed amyloid deposits. At six-month follow-up the patient showed complete normalization of the paresis, gait, sensory and urinary disturbances and resumed his work. Discussion and conclusion: Spinal leptomeningeal deposition of amyloid is a rare occurrence within the framework of ATTRv. Micro-neurosurgical complete resection of the lesion is feasible in patients with preoperative myelopathic symptoms and resulted in complete symptom relief in this case.