Hypertrophied posterior longitudinal ligament and ligamentum flavum causing myelopathy: a case report and literature review.

Introduction: The occurrence of concurrent hypertrophied posterior longitudinal ligament (HPLL) and hypertrophied ligamentum flavum (HLF) in the thoracic spine is a very rare presentation. This case report describes a young female who developed thoracic myelopathy secondary to a combination of both thoracic HPLL and HLF.
Case Presentation: A 30-year-old previously well female was referred for an MRI scan of the thoraco-lumbar spine. She was having lower limb weakness and difficulty in walking, which had progressed over 3 months. On examination, she was found to have spastic lower limbs with associated motor weakness. Her biochemical investigations were unremarkable. The MRI scan showed HPLL, which was uniformly hypointense on T2W images and was isointense on T1W images. The hypertrophied segment was extending from T2 level to T7 level. Similarly, the ligamentum flavum was hypertrophied from T1 level to T8 level. The thoracic spinal cord was seen compressed between the hypertrophied ligaments. The compressed cord showed central hyperintense signal pattern in T2W images. CT scan of the thoracic spine did not show any calcifications or ossifications along the ligaments. Patient underwent posterior decompressive surgery and she had an uneventful recovery.
Discussion: Although few cases of HPLL and HLF were reported in older patients in literature, both these conditions were found in this patient at a younger age. HPLL and HLF are thought to be precursors of ossification of these ligaments and these patients need long-term follow-up.
(© 2023. The Author(s), under exclusive licence to International Spinal Cord Society.)