Ponticulus Posticus: Espy before Apocalypse in Craniovertebral Junction Surgery
Year: 2025
Type: article
Study design: Case Report
Abstract: A 45-year female, known case of hypertension, hypothyroidism and rheumatoid arthritis presented with neck pain, spastic quadriparesis, tingling paresthesia’s in all limbs with bladder and bowel involvement for past 3 years. The patient had MAS grade I spasticity, 4/5 power in all limbs with exaggerated deep tendon reflexes and bilateral extensor plantar response. MRI cervical spine showed Atlanto-Axial dislocation (AAD) with compressive myelopathy [Figure 1a and b]. CT was suggestive of fixed AAD with arcuate foramen Atlantis [Figure 1c and d]. CT vertebral angiogram revealed incidentally detected bilateral arcuate foramen Atlantis [Figure 2a] with bilateral vertebral artery entering into the foramen [Figure 2b-d]. Patient was managed with bilateral infra-isthmic C1 lateral mass and C2 pars screws fixation achieving complete reduction of ADI [Figure 2e].Figure 1: (a and b) MRI showing abnormal bony craniovertebral junction and narrowing of the foramen magnum with compression at cervico-medullary junction. (c and d) CT cervical spine showing Atlanto-Axial dislocation (AAD) with arcuate foramen AtlantisFigure 2: (a) CT cervical spine showing incidentally detected complete bilateral arcuate foramen Atlantis. (b-d) CT vertebral angiogram showing complete bilateral arcuate foramen in which the vertebral artery is seen running through a bony canal from transverse foramen to arcuate foramen. (e) Post-op CT cervical spine showing completely reduced ADI with restored spinal canal diameterPonticulus posticus is a normal anatomical variant of atlas vertebrae (C1) and resides in the posterior arch of atlas in relation to vertebral artery. It is an incidental finding visualized in lateral cervical spine x-ray or CT. Ponticulus posticus in Latin means “little posterior bridge.”[1] Other synonyms for ponticulus are arcuate foramen, Kimerle’s anomaly, retroarticular foramen and retocondylar foramen with incidence reported to be 16.7%. Literature reveals a higher incidence in females, unaffected by age.[2] This additional bone is formed by the calcification of posterior-atlantooccipital membrane. Three variations are seen radiographically: complete, partial, and calcified forms.[3] The complete form is where the bony ring is fully formed, thus, resembling a foramen. The incomplete form has deficiencies in the bony segment; thus, it does not completely develop into a ring shape. Lastly, the calcified type is merely a linear or amorphous calcification. It can be either unilateral or bilateral. This entity is known to contribute to stress related to headaches of chronic type, migraine disorder, dizziness, double vision, stroke, shoulder pain, neck pain. During intervention of cervical vertebrae, insertion of surgical screws can cause injury to vertebral artery and suboccipital nerve if the surgeon is not aware of the so-called bony anomaly.[4] This in turn can cause massive hemorrhage, reduced blood circulation, lateral medullary syndrome, quadriparesis, headache in future and even mortality in some case. Expert surgeons in such cases have recommended to use a modified screw trajectory to avoid piercing the vertebral artery and closely related structures. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Source: Neurology India
Language: English
Subfield: Surgery
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
OpenAlex ID: W4411435361