Speakers

Ossification of the Ligamentum Flavum: unknown facets of the disease
1109 13:25-13:35
Spine/304A
Introduction : Ossification of the ligamentum flavum is a common cause of myelopathy in Asians. The aim of this study is to report this author’s experience with 41 cases of Ossification of ligamentum flaum (OLF) Methods: All patients with myelopathy due to OLF treated by this author were included. Neurological status was graded using Nurick’s scale and modified JOA score. Whole spine MRI & CT of the spine at the affected levels to look for dural ossification were performed.The excised specimen was submitted for identification of calcium pyrophosphate dihydrate deposition disease (CPPD). Patients were also evaluated for the presence of fluorosis ,DISH or other known causes of OLF . Complications were recorded and the postoperative status was assessed. Mean follow up was 14 months. Results: Period of study : 1998 -2020. Lower thoracic region was the most commonly involved site, especially, T9- T12 followed by mid and upper thoracic levels. Three patients had cervical OLF. Associated cervical OPLL was found in 6 patients and one patient had spinal syringomyelia induced by OLF. The cause of OLF could be identified in 22 patients: 13 had CPPD, 3 had fluorosis; 4 had DISH, 1 had myositis ossificans progressiva and 1 had renal rickets. Dural ossification was found in 13 (32%) of patients. Thirty nine patients underwent surgery. One patient each with renal rickets and myositis ossificans progressiva did not undergo surgery. Dural ossification was associated with increased risk of dural lacerations and CSF leaks. Postoperative deterioration was encountered in 3 patients. Conclusions: OLF is an under recognized cause of thoracic myelopathy . The aetiology of this entity can be identified in the majority of the patients. Dural ossification is associated with increased postoperative morbidity.

Craniovertebral Junction surgery in mucopolysacchridoses - Lessons Learned
1109 13:35-13:50
Interim Meeting of AASPN/303A
Introduction: Morquio’s – Brailsford disease is one type of mucopolysaccharidoses. Patients with Morquio’s disease have a high predilection for cervicomedullary compression due to the high prevalence of odontoid hypoplasia and ligamentous laxity and accumulation of glycosaminoglycans in the craniovertebral junction (CVJ). The aim of this study is to report this author’s experience in surgical management of children with Morquio’s disease and CVJ instability. Methods : Five Children age ranging from 6 years to 12 years were included in the study; Male : Female – 2:1. Three presented with quadriparesis and one was bedridden at the time of presentation. Remaining two were evaluated for orthopaedic anomalies. All the children had classical clinical features of Morquio’s – Brailsford disease which included clouding of the cornea, pectus carinatum, short stature, short neck, deformity of the extremities. The radiological features included hypoplasia of the odontoid, atlantoaxial dislocation, high cervical cord compression with intramedullary signal changes, bullet shaped vertebrae. Three children had combined bifid anterior and posterior arches of atlas. One child had, in addition, abnormal cervicothoracic kyphosis and thoracolumbar kyphosis without cord compression at these levels where as the other two children did not have this radiological feature. Results: Three of the five children underwent stabilization of the craniovertebral junction. Other two children did not undergo surgery as they did not exhibit features of myelopathy and hence are under close clinical and radiological observation. One of the three children underwent surgery with intraoperative neuromonitoring whereas the other two did not undergo intraoperative monitoring. One child underwent a classical Goel-Harm’s fusion, one underwent C1-C2 transarticular screw fixation and the third child underwent occipitocervical fusion. The surgical option was individualized for each patient depending upon the intraoperative and preoperative findings and anatomical peculiarities of the individual case which will be discussed in the presentation. All the three children improved neurologically including the child who was bedridden preoperatively. This child could walk without support six months postoperatively. Postoperative CT scans of the spine revealed good screw positions and reduction of the atlantoaxial stabilization with adequate decompression of the cervicomedullary junction. Follow up ranged from 12 to 36 months. During last follow up, the remaining two children treated conservatively were stable without neurological deterioration. Conclusions: Craniocervical instability is common in children with Morquio’s – Brailsford disease. Every child with Morquio’s disease should be radiologically evaluated for the presence of craniocervical instability as sudden deaths have been reported in children with this condition. Surgical options should be individualized depending upon the age, anatomical variations including the presence of bifid anterior and posterior arches of atlas. Anatomical variations peculiar to this condition can complicate surgery as follows: difficult intubation, the presence of pectus carinatum can make postioning difficult and may increase the intrathoracic pressure leading to congestion of the suboccipital venous plexus. The exaggerated thoracic kyphosis can complicate transarticular C1-C2 fixation. Though rare, surgeons operating in this regions should be familiar with the management of this entity. Surgical nuances and precautions while operating on these children will be discussed.