(Kiosk 6) Congenital Absence of the Posterior Arch of C1 in Pediatric Traumatic SCI: A Case Report

Case Diagnosis: A 14-year-old male presents to hospital with a GCS of 11, intubated with no motor function as result of left vertebral artery dissection and spinal ischemic stroke. Patient had an incidental finding on admission MRI of a congenital absence of the right posterior arch of C1.

Case Description or Program Description: Patient is a 14-year-old male with no significant past medical history who presented to level 1 trauma center as GCS 11 with loss of respiratory capacity, motor, and vasomotor tone. Patient had a mild head-on collision with another student while playing basketball, but no physical or mental sequelae were noted. Patient displayed delayed upper and lower extremity paresthesia, weakness, and mental status decline 1 hour post the incident while in class. Patient had a GCS of 6 upon arrival of EMS, intubated for airway protection on scene and subsequently transferred to a level 1 trauma center. Admission MRI demonstrated infarction within the cervical anterior spinal artery vascular territory along with left vertebral artery dissection. An incidental finding on MRI is the congenital absence of the posterior arch of the C1 on the right side. Patient was discharged from hospital to inpatient rehabilitation as C1 ASIA B Sensory Incomplete SCI.

Setting: Pediatric Inpatient Physiatry Consult

Assessment/Results: MRI on admission with coincidental finding of congenital absence of posterior arch of the right C1 vertebrae.

Discussion (relevance): Congenital absence of the posterior arch of C1 can present asymptomatically or contribute to neurologic deficits due to instability. As a result, it may be a potentially significant risk factor for spinal cord ischemic events. This structural abnormality is most often found incidentally and screening would be impractical, however, awareness is crucial given the rarity and potential to contribute to severe functional impairment as demonstrated by this case.

Conclusions: Congenital absence of the posterior arch of C1 can present asymptomatically and is most often found incidentally. Awareness of this congenital condition may prevent development of similar spinal cord ischemic events culminating in severe functional impairment.