Spinolaminar Line Test as a Screening Tool for C1 Stenosis

Atlantoaxial stenosis after muscle-preserving selective laminectomy

There are few reports of degenerative atlantoaxial stenosis and new stenosis after cervical decompression. We experienced four cases of atlantoaxial stenosis after muscle-preserving selective laminectomy. We compared these four cases with no stenosis cases after long-term follow-up of selective laminectomy, as well as healthy subjects. A total of 1205 patients who underwent muscle-preserving selective laminectomy due to cervical disorders were included in this study. Postoperative atlantoaxial stenosis, which needed decompression, appeared in 4 cases, and 30 patients did not have radiological stenosis for more than 10 years after surgery. Twenty healthy volunteers were also used as controls. The radiographic parameters measured were C2-C7 angle, C2-C7 sagittal vertical axis (SVA), C2 slope, C7 slope, C2-C5 angle, C5-C7 angle, C1-C2 angle, and atlantodental interval (ADI). We measured the anterior-posterior (AP) diameters of the spinal cord (SC) and dural tube (Dura) at C1/C2 with sagittal MRI. In the cases of atlantoaxial stenosis, the AP of SC and Dura at C1/C2 were smaller preoperatively, and the residual space for SC (SAC) was also smaller. The preoperative ADI was significantly higher in patients with atlantoaxial stenosis, suggesting preoperative instability at C1/C2. Analysis of the ROC curve showed that patients with a preoperative SAC of less than 3.6 mm and an ADI of more than 1.35 mm were more likely to develop postoperative atlantoaxial stenosis. When we perform a muscle-preserving selective laminectomy, decompression of C1/C2 is suggested when the SAC at C1/C2 is less than 3.6 mm and the ADI is more than 1.35 mm.

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.

A surgical case of C1 arch stenosis: A case report and review of literature

Background:

Isolated symptomatic cervical stenosis of the atlas is quite rare; there have been 11 cases reported in literature.

Case Description:

A 76-year-old male presented with myelopathy attributed to C1 arch stenosis. Neuroimaging studies revealed posterior atlas compression of the spinal cord. Following a cervical laminectomy involving excision of the arch of the atlas, and the patient’s symptoms resolved.

Conclusion:

C1 stenosis resulting in cervical myelopathy due to posterior compression from the arch of the atlas is easily missed. Notably, C1 arch laminectomy may be very effective in resolving this entity.

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.

Variation of C1 spinolaminar line and prevalence of C1 stenosis in normal population

BACKGROUND

The variation of C1 spinolaminar line in normal population is not fully understood. The relative position of C1 lamina to C3-C2 spinolaminar line is reported as good screening tool for determination of C1 canal stenosis.

OBJECTIVE

To determine the variation of C1 spinolaminar line and find the prevalence of C1 canal stenosis in normal population using C3-C2 spinolaminar test.

MATERIALS AND METHODS

Three hundred and fifteen lateral cervical radiographs from 315 volunteers without neurological symptoms were analyzed. The relative position of C1 spinolaminar line was determined by C3-C2 spinolaminar and considered positive if C1 lamina lay ventral to C3-C2 line. C1 space available for cord (SAC) was measured from posterior border of dens to the C1 lamina to determine the sagittal diameter.

RESULTS

The mean sagittal spinal canal diameter of C1 was 22.2 mm (13-26 mm). Of 315, 14 (4.4%) had positive, 184 (58.4%) had neutral, and 117 (37.1%) had negative C1 spinolaminar line in relation to C3-C2 line. The mean SAC among positive group was 14.9 mm compared to neutral and negative groups which were 22.2 and 23.3 mm, respectively. 21.4% of positive group had SAC of less than 12 mm. The 92.8% of positive C1 spinolaminar line was found in age ≥ 60 years.

CONCLUSION

In a normal population, 4.4% has positive C1 spinolaminar line. The C1 stenosis is more prevalent in positive C1 spinolaminar line group.