Os odontoideum

Abstract

Os odontoideum (OO) is a rare craniocervical anomaly that is characterized by a round ossicle separated from the C2 vertebral body. With a controversial etiology and unknown prevalence in the population, OO may be asymptomatic or present in patients with myelopathic and neurological symptoms. In this literature review, we aimed to investigate epidemiology, embryology, pathophysiology, clinical presentation, and the role of diagnostic radiography in OO. By providing an overview of different management strategies, surgical complications, and postoperative considerations for OO, our findings may guide neurosurgeons in providing proper diagnosis and treatment for OO patients. A literature review was conducted using the PubMed, EMBASE, and Scopus databases. A search using the query “os odontoideum” yielded 4319 results, of which 112 articles were chosen and analyzed for insights on factors such as etiology, clinical presentation, and management of OO. The presentation of OO varies widely from asymptomatic cases to severe neurological deficits. Asymptomatic patients can be managed either conservatively or surgically, while symptomatic patients should undergo operative stabilization. Although multiple studies show different techniques for surgical management involving posterior fusion, the diversity of such cases illustrates how treatment must be tailored to the individual patient to prevent complications. Conflicting studies and the paucity of current literature on OO highlight poor comprehension of the condition. Further understanding of the natural history of OO is critical to form evidence-based guidelines for the management of OO patients. More large-center studies are thus needed to promote accurate management of OO patients with optimal outcomes.

Os odontoideum with progressive symptoms: case report

“…Late neurologic deterioration occurs in only 4% of patients. 2 In our patient, neurologic examination findings were normal except for a gradually increasing number of symptoms over the last few years. These symptoms included difficulty in performing fine manual skills such as buttoning buttons and pulling zippers, numbness in the hands, and the occasional sensation of stepping on a gap when walking.…”

“…3 The congenital hypothesis argued incomplete fusion of the dens and axis vertebral bodies (segmental defects) due to developmental failure of the synchondrosis during embryonic development, non-traumatic osteonecrosis, congenital malformations (neurofibromatosis, skeletal dysplasias), autosomal dominant inheritance. 2 In the traumatic theory, it is argued that contraction of the alar ligament following an unrecognized odontoid fracture may lead to avascular necrosis and osseous remodeling contributing to ossicle formation. At the same time, deficiencies in arterial blood supply and trabecular bone at the base of the dens may predispose the dens to stress fractures caused by repeated microtrauma.…”

“…Conservative treatment is recommended for asymptomatic patients, while surgical treatment is recommended for symptomatic patients. 2 In this case report, a patient with os odontoideum is discussed.…”