Arthritis in Children with Psychiatric Deterioration: What This Case Series Shows
Please Note the following about Lyme and Bartonella, not discussed in the paper:
- Lyme arthritis typically shows objective joint swelling and fluid in the joint — i.e., “wet” arthritis that is detectable on exam and imaging. Source
- Bartonella-related joint symptoms (based on available research) are more often described as pain, arthralgia, or progressive arthropathy and may not always have large effusions, aligning with what is sometimes referred to in practice as “dry” arthritis — though the exact mechanisms are still under study. Source
Why authors examined arthritis in this population
Psychiatric symptoms and musculoskeletal disease are rarely considered together in pediatrics. This case series addresses that gap by describing children with severe psychiatric deterioration who later developed chronic inflammatory arthritis. In many cases, joint disease was subtle, relied on imaging for detection, and was often overlooked.
Pediatric Acute-Onset Neuropsychiatric Syndrome (PANS) is defined by the sudden onset of severe obsessive-compulsive symptoms and/or eating restriction, accompanied by additional abrupt neuropsychiatric changes. These symptoms can cause profound distress, disability, and caregiver burden. A related condition, PANDAS, is thought to share overlapping pathophysiology with Sydenham chorea and is likewise considered post-infectious in origin.
Previous research found high rates of inflammatory back pain, enthesitis, and arthritis in patients with psychiatric deterioration. This paper describes these cases in detail, highlighting the overlap between psychiatric symptoms and inflammatory joint disease, which may result from a shared systemic inflammatory response after infection.
How common was arthritis in this cohort?
Among 193 consecutive patients meeting strict PANS criteria, 55 patients (28%) developed chronic arthritis after PANS onset. In a comparison group of 121 patients with severe psychiatric deterioration that did not meet PANS criteria, 25 patients (21%) also developed chronic arthritis.
The paper provides detailed descriptions of seven patients and one sibling to illustrate clinical patterns seen in the broader cohort.
Atypical arthritis: often “dry” and easy to miss
A central finding is that arthritis in this population often differs from classic childhood inflammatory arthritis on physical examination.
Many patients had:
- No obvious joint swelling on exam
- Minimal or inconsistent pain reporting
- Significant sensory dysregulation, making examination unreliable
Instead, arthritis was often identified through imaging, which revealed:
- Subtle joint effusions
- Synovitis and enthesitis
- Features of spondyloarthritis
- Joint capsule thickening, a finding reported in adults with psoriatic arthritis but not previously in children
Severe psychiatric symptoms, including OCD, anxiety, depression, and psychosis, often overshadow joint complaints, causing musculoskeletal disease to go unrecognized for years. The authors note that arthritis often developed long after psychiatric symptoms began.
Why imaging mattered so much
The authors emphasize that imaging was essential for accurate diagnosis in this population. Physical exams were often limited by psychiatric severity, sensory dysregulation, and limited patient cooperation.
Imaging was particularly important when families reported:
- Reduced physical activity
- Avoidance of previously enjoyed movement
- Morning stiffness
- Altered gait after rest or prolonged sitting
Ultrasound often showed synovial and capsular thickening, supporting the diagnosis of inflammatory arthritis even when physical exams were inconclusive.
Treatment approaches and observed patterns
Initial treatment for arthritis typically begins with nonsteroidal anti-inflammatory drugs (NSAIDs), which the authors note have also been shown to reduce PANS flare duration and symptoms.
If imaging showed significant capsular or synovial thickening and symptoms persisted, treatment was escalated to disease-modifying antirheumatic drugs (DMARDs) and, in some cases, biologic or immunomodulatory therapies.
For patients with refractory psychiatric symptoms and arthritis, the authors describe escalation to treatments used in other conditions with overlapping psychiatric and inflammatory disease, including:
- Azathioprine
- Mycophenolate mofetil
- Rituximab
In these cases, improvement in psychiatric symptoms was observed alongside arthritis treatment.
The authors also note treatment challenges unique to this population. Many patients had sensory dysregulation, chemosensitivity, and poor tolerance to standard escalation protocols, requiring slower, more individualized approaches.
A possible psoriatic arthritis connection
The presence of capsular thickening on imaging led the authors to consider a psoriatic arthritis subtype, given known links between group A streptococcal infection and psoriasis. While this pattern has been described in adults, it has not been previously reported in children.
The authors note that IL-17 inhibitors were used in refractory psoriatic arthritis cases, while TNF inhibitors were generally avoided as first-line therapy because of concerns about demyelinating disease and lupus-like features in this population.
What the authors think may be happening
The discussion explores two non-mutually exclusive possibilities:
- Infection-triggered systemic inflammation that affects both the brain and joints
- Underlying immunogenetic susceptibility that predisposes patients to multiple inflammatory conditions over time
The delayed onset of arthritis, often years after psychiatric symptoms, suggests that additional triggers or immune maturation may be needed for musculoskeletal disease to become clinically apparent.
Why this matters
This case series highlights a population that does not fit neatly into traditional psychiatric or rheumatologic frameworks. These children often present first with overwhelming psychiatric symptoms, while inflammatory joint disease develops quietly and later.
The authors argue that patients with overlapping psychiatric deterioration and arthritis present unique diagnostic and treatment challenges and benefit from multidisciplinary care. Imaging plays a key role in identifying treatable inflammatory diseases.
Conclusion
This study reports seven children with severe psychiatric deterioration and objective evidence of inflammatory arthritis, often “dry,” imaging-dependent, and delayed in onset. The authors suggest that psychiatric and musculoskeletal symptoms in these patients may reflect a shared systemic inflammatory response, similar to what is seen in post-infectious and post-COVID autoimmune conditions.
When selecting immunomodulatory treatment for arthritis in this population, the authors emphasize the importance of considering potential effects on psychiatric symptoms, recognizing that both may result from the same underlying inflammatory process.
Gabriella True
