Frequency of Grisel's Syndrome
Grisel's syndrome is an extremely rare condition with no established population-based incidence data available in the medical literature.
What We Know About Its Rarity
The available evidence consistently describes Grisel's syndrome as a rare or uncommon entity, but provides no specific incidence rates:
No population-based incidence studies exist for Grisel's syndrome, unlike conditions such as Guillain-Barré syndrome where incidence rates of 0.16-3.0 cases per 100,000 persons/year have been documented across different populations 1.
The condition is described as "rare" 2, "uncommon" 3, and "extremely rare" in adults 4 throughout the published literature.
One case series identified only 5 cases over 5 years at a single otolaryngology center 2, suggesting the condition is encountered infrequently even at specialized referral centers.
A systematic review of pediatric cases identified only 171 pediatric patients reported in the entire published literature through 2020 5, highlighting how rarely this condition is documented globally.
Age Distribution Pattern
Grisel's syndrome predominantly affects children, though adult cases do occur:
The condition "usually affects children" 2, 3 and is described as "primarily in children" 4.
Of 171 cases identified in systematic review, the pediatric population represented the vast majority, with adult-onset cases being "extremely rare" 4.
The pediatric predominance likely relates to anatomical factors including greater ligamentous laxity and increased vascularity of the atlantoaxial region in children 3.
Clinical Context for Recognition
The condition occurs following specific triggers that help define its clinical context:
Among reported pediatric cases, 59.7% presented after head and neck infection and 35.7% occurred after head and neck surgery 5.
Common precipitating infections include otitis media, pharyngitis, and upper respiratory tract infections 3.
Common surgical triggers include adenoidectomy and other ENT procedures 5.
Mean delay in diagnosis is 33 days 5, suggesting the condition is frequently missed initially due to its rarity and unfamiliarity among clinicians.
Important Clinical Caveat
The true frequency may be underestimated because:
The condition "may remain undiagnosed at initial presentation if not suspected" 2.
Many cases may resolve spontaneously or be misdiagnosed as simple torticollis without imaging confirmation.
Publication bias likely favors reporting of complicated or unusual cases rather than straightforward presentations.