Concurrent Ossification of the Posterior Atlantoaxial Interlaminar Membrane and Atlas Hypoplasia: A Case Report

Ossification of posterior atlantoaxial membrane causing spinal stenosis - A case report

Background

Ossification of the posterior atlantoaxial membrane (PAAM) is a rare cause of spinal cord compression.

Case presentation

A 46-year-old woman with rheumatoid arthritis (RA) and a 2-year history of slowly progressive gait disturbance underwent surgery for right knee stiffness and right lower limb mild weakness. A neurologic examination revealed brisk deep tendon reflexes (DTR) and spasticity in her four limbs. A computed tomography (CT) scan revealed spinal stenosis caused by ossification of the PAAM, a rare cause of spinal cord compression. The patient's lower limbs weakness and walking capability were ameliorated post-surgery.

Conclusions

Although the exact mechanism of ossification of PAAM remains unclear, chronic mechanical stress as well as persistent atlantoaxial instability may promote the development of the ossification.

Effect of C1 Single-door Laminoplasty on Symptomatic Atlas Canal Stenosis

OBJECTIVE

To verify the effect of single-door laminoplasty combined with atlantoaxial fusion in the treatment of symptomatic atlas canal stenosis.

METHODS

This is a single-center retrospective analysis. From February 2014 to January 2019, 16 patients (five were females) with an average age of 63.4 years (56-71 years) were enrolled in this study. Patients with compressive cervical myelopathy with CT scan showed an inner sagittal diameter (ISD) of C₁ less than 29 mm or C1 canal space available for cord (SAC) of <12 mm were included, while isolated C1 stenosis without myelopathy or isolated C1 stenosis without atlantoaxial subluxation were excluded in this study. All patients underwent continuous heavy-weight skull traction, atlas single-door laminoplasty and atlantoaxial fusion. The differences in the pre- and post-operative inner sagittal diameter, space available for cord, atlas-dens interval (ADI) and compression of the spinal cord were analyzed by using CT and MRI. Functional evaluation was performed by using the Japanese Orthopaedic Association scoring system and the Neck Disability Index scoring system.

RESULTS

Single-door laminoplasty provided a full decompression for the spinal cord while retaining the whole posterior arch. No complications were encountered except a superficial wound infection in one patient. At final follow-up, The ADI was significantly reduced from 5.2 ± 1.8 mm to 1.7 ± 0.6 mm after surgery on average (P < 0.05). Average inner sagittal diameter of C1 was increased from 26.3 ± 2.6 mm to 34.9 ± 2.9 mm and the space available for cord was increased from 6 ± 1.7 mm to 17.8 ± 3.6 mm (P < 0.05). Meanwhile, the Japanese Orthopaedic Association (JOA) score of the 16 cases was improved from 11.4 ± 1.8 to 14.1 ± 1.4 on average (P < 0.05). The postoperative neck pain VAS score decreased significantly, from 2.6 ± 1.0 preoperatively to 1.3 ± 0.9 postoperatively (P < 0.05). The influence of neck pain on patient's life was improved from 17.8 ± 3.9 to 13.9 ± 3.3 after surgery (P < 0.05). At the last follow-up, the healing of the hinge fracture and the fusion between atlas and axis were observed in all patients.

CONCLUSIONS

Single-door laminoplasty combined with atlantoaxial fusion not only provides enough space for decompression but also offers intact arch for bone grafting, suggesting that it might provide a more feasible method for the correction of symptomatic atlas canal stenosis.

Percutaneous full endoscopic C1 laminectomy for developmental atlantal stenosis with myelopathy: a case report of three cases and review of the literature

Background

Developmental atlantal stenosis with myelopathy (DASM) in adults is a rare disease that only sporadic cases have been reported over the years. C1 laminectomy (C1L) is one of the most common operations for its treatment. However, as an open surgery, it has shortcomings such as large trauma and slow postoperative rehabilitation, and minimally invasive spine surgery (MISS) offers alternative treatment options with advantages. MISS instruments expand the technical capabilities of surgeons, which allows safer and more effective therapeutics for difficult and complicated diseases. This case report presents a new minimally invasive approach; percutaneous full endoscopic C1 laminectomy (PFEC1L), for the treatment of DASM, and to consolidate the current literature on the condition to summarize its etiologies, clinical manifestations, diagnostic criteria, surgical management, and prognoses.

Case Description

The patient in Case 1 presented with neck pain and numbness and weakness in the limbs. The patient in Case 2 presented with numbness in the extremities and the patient in Case 3 presented with bilateral hand numbness and left lower limb weakness. They were all diagnosed with DASM and underwent PFEC1L treatment to maintain the enlargement and decompression of the atlantal canal, which achieved favorable outcomes without complications during the postoperative follow-up visit.

Conclusions

DASM is rare but potentially dangerous. Its diagnosis is made based on clinical manifestations combined with radiological imaging examinations, especially computed tomography (CT) scan and magnetic resonance imaging (MRI). While C1L is the most common surgical method, PFEC1L is a new feasible and safe therapeutic option with comparable good outcomes and the advantage of being minimally-invasive. To our knowledge this is the first report that PFEC1L was applied for DASM treatment.