Functional tremor

Functional movement disorders represent a multifaceted and debilitating condition characterized by diverse clinical symptoms that do not align with the neuroanatomy and neurophysiology of typical neurological diseases. The terminology has evolved over time, with "functional" replacing terms like "psychogenic," "conversion," and others, aiming to eliminate etiological implications lacking bedside support. Functional movement disorders comprise approximately 1.5% of patients. Among adults and children, functional tremor emerges as the predominant phenotype, followed by functional dystonia. Diagnosis relies heavily on positive phenomenologic features rather than exclusionary criteria, emphasizing the need for a phenotype-based approach supported by expert neurological examination. The diagnostic process is complex, with sensitivity and specificity influenced by various factors, including the lack of gold standards for comparison and unblinded assessments. Functional tremor diagnosis necessitates specialized expertise due to its incongruence with typical neurological patterns and reliance on nuanced examination findings.
While the exact pathophysiology remains elusive, excessive attentional focus, abnormal beliefs, and impaired sense of agency play pivotal roles. Neurobiological models highlight the interplay between self-focused attention and abnormal predictions related to movement, leading to involuntary actions devoid of normal voluntary control. Amygdala hyperactivation and functional connectivity alterations are implicated as potential biological markers, underscoring the complexity of functional movement disorders. Management prioritizes comprehensive assessment, patient education, and fostering a trusting patient-doctor relationship to coordinate long-term care effectively. Recent years have witnessed a surge in controlled treatment trials, emphasizing the need for standardized outcome measures. Multidisciplinary treatment approaches, tailored to individual symptoms and comorbidities, are preferred in clinical practice, with outpatient or inpatient settings chosen based on disability severity.