Craniocervical instability after inadvertent neck hyperextension in Ehlers-Danlos syndrome: a retrospective case series and literature review.

BACKGROUND: Patients with hypermobile Ehlers-Danlos Syndrome (hEDS) are at risk of developing craniocervical instability (CCI). Iatrogenic causes of CCI in hEDS are underreported. We describe a case series of hEDS patients who developed CCI from routine neck hyperextension during common procedures (e.g., intubation for anesthesia, dental work). METHODS: We conducted a retrospective case series of 8 adults (≥ 18 years old) with hEDS (2017 diagnostic criteria) who had no preoperative CCI symptoms but developed new CCI symptoms after a surgical procedure that persisted for at least 5 years. Cases were identified from patients seen at a single tertiary center between January 1, 2024, and July 31, 2025. Data collected included symptom onset, symptom types, procedure details (including neck positioning), imaging findings, and clinical outcomes. A structured literature review was performed using PubMed, Scopus, and Web of Science (through November 2025) for reports of CCI in EDS, including terms “Ehlers-Danlos syndrome,” “craniocervical instability,” “atlantoaxial instability,” “occipitocervical fusion,” “upper cervical instability,” “neck hyperextension,” and “ligamentous laxity.” RESULTS: All 8 patients were female (mean age 26.3 ± 6.0 years). Three patients underwent dental extractions, two had laparoscopic appendectomy, one had laparoscopic cholecystectomy, one had turbinate reduction, and one had upper endoscopy. Four cases involved prolonged neck hyperextension without intubation, whereas the remaining four involved neck hyperextension with intubation. Common presenting CCI symptoms included occipital headache, dizziness, tinnitus, neck instability (with crepitus/clunking), “brain fog” (cognitive dysfunction), and dysautonomia. Symptom onset ranged from the day of surgery (postoperative day 0) to 4 weeks postoperatively, with 5 patients (62.5%) developing symptoms in the first post-operative week. All patients were evaluated by neurosurgeons. CCI was confirmed by imaging (MRI in 7 cases, CT in 1 case). Literature review revealed no previous literature documenting CCI triggered by intubation or dental positioning in this population. CONCLUSIONS: This case series provides the first evidence that hEDS patients without preexisting CCI can develop CCI due to routine perioperative neck hyperextension. Even minor neck hyperextension during common procedures (such as intubation or dental work) may precipitate symptomatic CCI in this population. Heightened perioperative caution, including gentle airway management and neutral neck positioning (with adjuncts like cervical collars when appropriate), is warranted to prevent long-term neurologic sequelae.