Atlas hypoplasia and ossification of the transverse atlantal ligament: a rare cause of cervical myelopathy

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.

Ossification of the posterior longitudinal ligament at the craniocervical junction presenting with Brown-Séquard syndrome: A case report

Background:

Several case reports about spinal cord compression due to hyperostosis at the craniocervical junction are available. However, compression at C1-C2 solely due to ossification of the posterior longitudinal ligament (OPLL) is rare.

Case Description:

A 50-year-old Asian male, with a history of lumbar spinal canal stenosis, presented with a progressive quadriparesis within 3 months. Imaging showed central OPLL at the C1-C2 level contributing to severe spinal cord compression. The patient improved neurologically after a C1-C2 laminectomy.

Conclusion:

A patient presented with a progressive Brown-Séquard syndrome due to OPLL at the craniocervical junction (C1-C2 level) and improved following a decompressive laminectomy.

Symptomatic Atlas Hypoplasia in a Latin-American Patient: Case Report and Literature Review

Background:

Atlas hypoplasia is an infrequent cause of upper cervical stenosis. Only 24 cases in nonsyndromic adult population have been published. We are not aware of previous reports describing isolated fully formed atlas hypoplasia in a Latin-American patient. The purpose of this work was to report a case of an 80-year-old Argentinian woman with cervical myelopathy because of atlas hypoplasia and a literature review about this subject.

Methods:

A clinical case and an extended review of the literature are presented. We assessed from each case: age, sex, posterior atlanto-dens interval, surgical treatment, outcomes, and follow-up period.

Results:

Neurologic symptoms markedly improved after posterior decompression from severe to moderate in the Japanese Orthopaedic Association Scoring System and from four to three on the Nurick scale. Twenty-five patients were analyzed (mean 58.4 years, 32% female). The mean posterior atlanto-dens interval was 8.8 mm. Twenty-three patients underwent decompression alone, and two needed posterior fusion. All patients reported clinical improvement at an average follow-up of 13 months.

Conclusion:

Cervical myelopathy caused by fully formed atlas hypoplasia is not an exclusive pathology of far east population, and it may present in nonsyndromic patients. Surgical treatment by C1 laminectomy improved neurologic impairment.

Study Design:

Case report and literature review.

C1 Stenosis - An Easily Missed Cause for Cervical Myelopathy

C1 stenosis is often an easily missed cause for cervical myelopathy. The vast majority of cervical myelopathy occurs in the subaxial cervical spine. The cervical canal is generally largest at C1/2, explaining the relatively rare incidence of neurological deficits in patients with odontoid fractures. However, some subjects have anatomical anomalies of the atlas, which may cause stenosis and result in clinical symptoms similar to subaxial cord compression. Isolated pure atlas hypoplasia leading to stenosis is quite rare and may be associated with other anomalies, such as atlas clefts or transverse ligament calcification. It may also be more commonly associated with syndromic conditions such as Down or Turner syndrome. Although the diagnosis can be easily made with a cervical magnetic resonance imaging, the C3/2 spinolaminar test using a lateral cervical plain radiograph is a useful and sensitive tool for screening. Surgical treatment with a C1 laminectomy is generally necessary and any atlantoaxial or occipito-atlanto instability must be treated with spinal stabilization and fusion.

Ossification of the Cruciform Ligament of Atlas; a Rare Cause of Cervical Myelopathy: Case Report and Review of Literature

We present a case of cervical myelopathy secondary to ossification of the cruciform ligament (also known as cruciate ligament). This is a rare phenomenon that, to the best of our knowledge, has only been reported 16 times previously in literature. We have added a review of literature after our case presentation. We hope that by doing so, we may aid clinicians reach early diagnosis so as to be able to better manage this rare disease.

Ossification of the posterior atlantoaxial membrane associated with atlas hypoplasia: A case report

RATIONALE

Hypoplasia with an intact posterior arch of the atlas and ossification of the posterior atlantoaxial membrane (PAAM) are individually rare.

PATIENT CONCERNS

The patient presented with a 6-month history of progressive weakness and paresthesia of his lower extremities.

DIAGNOSES

Cervical myelopathy resulting from atlas hypoplasia and ossification of the posterior atlantoaxial membrane.

INTERVENTIONS

Laminectomy of the atlas with duroplasty.

OUTCOMES

Preoperative symptoms were alleviated.

LESSONS

In most reported cases, either atlas hypoplasia or ossification of the PAAM is responsible for patients' myelopathy. The case illustrated here, to the best of our knowledge, is the first one with coexistent atlas hypoplasia and ossification of the PAAM. And laminectomy of the atlas with duroplasty provided satisfied outcome.

Complex cervical spondylotic myelopathy: a report of two cases and literature review

STUDY DESIGN

A report of two cases with complex cervical spondylotic myelopathy (CSM) and review of the literature.

OBJECTIVE

To describe two unique patients with complex CSM due to simultaneous anomalies as anteroposterior compressions of the spinal cord in both upper and lower cervical spine, caused by hypertrophic transverse ligament of atlas (TLA), dysplasia of the posterior arch of atlas, disc herniation, hypertrophic ligamentum flavum and osteophytes.

METHODS

We present such two cases with clinical, imageological presentations, and describe the surgical procedure, to which both patients responded favorably.

RESULTS

The neurological functions of both patients gradually improved according to the JOA scores and VAS scores in preoperative clumsiness and gait disturbance during the mean follow-up period lasted for 18 months. The latest plain radiographs and computed tomography (CT) revealed good fusion without instrumental failure and magnetic resonance imaging (MRI) showed good decompression of C1-7 spinal cord of both patients. Both patients are progressively followed-up.

CONCLUSION

Posterior surgical approach as C1-7 laminectomy with fixations or occipital-cervical fusions may obtain better reconstructions of the cervical spine and good neurological recovery for the patients with complex CSM we present. However, the incidence and ethnic predisposition for the patients with complex CSM are still unclear.

Defining hyoplasia of the atlas: a cadaveric study

STUDY DESIGN

Cadaveric study.

OBJECTIVE

To define congenital hypoplasia of the atlas.

SUMMARY OF BACKGROUND DATA

Little has been written about hypoplasia of the atlas and it is usually described in the setting of other skeletal dysplasias or syndromes.

METHODS

A total of 543 cervical spine specimens were randomly selected from the Hamann-Todd collection. Sagittal and coronal diameters of the atlas, axis, and C3 (when available), and the dens diameter were measured using digital calipers. Correction for modern size and radiographical magnification was performed. Hypoplasia of the atlas was defined as the lowest 2.5% of measurements. The correlation between inner sagittal diameters at C1 and C3 was calculated.

RESULTS

The mean C1 inner sagittal diameter was 30.8 ± 2.4 mm (range, 23.5-38.1 mm). We defined C1 hypoplasia as an inner sagittal diameter value representing the smallest 2.5% of subjects. Because the mean was 30.8 mm, hypoplasia was defined as a diameter of ≤26.1 mm or less. Correcting for size and magnification of radiographs, hypoplasia is defined as an inner sagittal diameter of the atlas of 28.9 mm. Approximately 10% of cases had a dens that occupied more than 40% of the spinal canal at C1, thus not following Steel's Rule of Thirds. There was only a moderate correlation between the spinal canal diameter at C1 and at C3 (r = 0.483, N = 345; P < 0.001).

CONCLUSION

With an inner sagittal diameter of 26 mm or less, one may describe the atlas as hypoplastic. Ten percent of the specimens had an odontoid process that occupied more than 40% of the spinal canal at C1. There was little correlation between the inner sagittal diameter at C1 and the diameter at C3.

LEVEL OF EVIDENCE

N/A.