Atypical Symptoms Following Concussion: A Comprehensive Review of Functional Deficits.

Objective: While most concussions present with common symptoms, some patients experience atypical manifestations that challenge diagnosis and management. This review synthesizes studies reporting atypical post-concussive symptoms with individual patient-level data, focusing on functional neurologic disorders.

Methods: A systematic review was conducted across PubMed, EMBASE, and Cochrane Library databases (01/2000-08/2023). Inclusion criteria were: (1) study participants with concussion or mild traumatic brain injury, (2) trauma and/or sport-related injury, and (3) atypical symptoms without observable imaging findings. Atypical symptoms were defined as neurological symptoms not fully explained by traditional neuroanatomical or neuropathological correlates. Four independent reviewers screened titles, abstracts, and full texts. Data extraction included patient demographics, symptom characteristics, diagnostic methods, treatments, and outcomes.

Results: Of the 4725 screened studies, 15 met inclusion criteria (2000-2022). Studies originated from five countries, with 8 (53.3%) from the United States. All studies were case reports (n = 12, 80.0%) or case series (n = 3, 20.0%). The review identified atypical symptoms across five domains: speech disorders (n = 6 studies, primarily new-onset stuttering), psychiatric alterations (n = 4 studies, including dissociative symptoms, Ganser syndrome, and psychotic features), visual changes (n = 1 study), hearing/vestibular disturbances (n = 2 studies), and gait abnormalities (n = 2 studies). Recovery patterns varied widely, ranging from complete resolution within weeks to persistent symptoms over several years.

Conclusion: While most patients eventually improved with targeted interventions like speech therapy, psychiatric care, or physical therapy, recovery trajectories varied significantly. Larger prospective studies are needed to determine true incidence rates and establish evidence-based treatment protocols.