(Kiosk 5) Myelopathy Secondary to an Ossified Ligamentum Flavum in Achondroplasia: A Case Report

Case Diagnosis: Ossified ligamentum flavum causing myelopathy in a patient with achondroplasia.

Case Description: A 58-year-old female with achondroplasia presented to our outpatient musculoskeletal clinic for evaluation of radicular low back pain. At baseline, she ambulated with a walker ever since a lumbar surgery for unknown reasons 3 years prior. She experienced a fall 3 months before arrival to our clinic with resultant coccygeal pain without any weakness or numbness. At that time, she had an unremarkable X-ray of her lumbar spine and was subsequently referred to our clinic. She presented in a manual wheelchair and reported slowly increasing lower extremity weakness over the last two months with a sharp increase in weakness 2 weeks prior. On exam she had 0/5 strength in bilateral lower extremities, absent sensation from the waist down, and absent lower extremity reflexes. She was sent to the emergency department where a MRI showed severe ligamentum flavum thickening/ossification at the T10-T11 level with severe spinal cord stenosis and cord compression. She subsequently underwent emergent T10-T12 laminectomy. Her hospital course was complicated by neurogenic bowel/bladder, difficult pain control, and spasticity.

Discussion: On admission to the inpatient rehab service the patient was found to be a T12 American Spinal Injury Association Impairment Scale Grade C. She completed 22 days of inpatient rehabilitation with minimal improvement in strength but great improvements in independence measures.

Setting: Outpatient MSK Clinic/Inpatient Rehabilitation Hospital

Assessment/Results: There are several documented cases of patients with achondroplasia experiencing myelopathy secondary to thoracic stenosis from a thickened, ossified ligamentum flavum. Significant functional decline can occur without swift recognition and treatment. However, in cases with delayed presentation to a medical provider, significant recovery of independence measures is still possible.

Conclusion: Physiatrists should be cognizant of a possible association between achondroplasia and ossification of the ligamentum flavum. Delaying appropriate surgical treatment can significantly reduce potential functional recovery.