Where Does It Hurt? The Distribution of Painful and Non-Painful Sensory Disturbances in Carpal Tunnel Syndrome

PURPOSE: Hand diagrams were first studied in 1990 by Katz et. al. as a diagnostic tool, but the use of the hand diagram as an epidemiologic investigational tool has not been thoroughly explored. The compiling and tracking of patient perceived data can also be used to establish clinically relevant normative data. We explore a novel method of patient reported symptom mapping to establish and compare the normative distribution of painful and non-painful symptomatology in patients diagnosed with median neuropathy.

 

METHODS: New patients were given a visual questionnaire consisting of a photo of human hand and wrist and a superimposed numbered grid. Patients were instructed to map their symptoms, painful symptoms noted with an “X” and non-painful sensory disturbance (i.e. numbness or tingling) noted with an “O.” Patients were instructed not to put marks where they lacked any symptoms. Grid cells could contain both an “X” and an “O.” All patients were then evaluated by a single, hand fellowship trained surgeon, who was blinded to questionnaire results, and a visit diagnosis was made. Questionnaires of patients with an isolated clinical diagnosis of carpal tunnel syndrome were compiled for inclusion in the study. Those with any conflicting or confounding diagnoses (e.g. symptomatic osteoarthritis, tendinosis, recent trauma) in the same limb were excluded. The frequency with which patients marked either painful or non-painful sensory disturbance was tallied and recorded for five discrete anatomic areas: the volar forearm (zone 1), carpal tunnel (zone 2), distal palmar (zone 3), radial three digits (zone 4), and ulnar two digits (zone 5). A frequency score was calculated by dividing the total number of marks in that symptom area across all patients by the total number of marks made by all patients. Photo-editing software was then used to create a visual frequency distribution for both painful sensation and non-painful sensory disturbance. Higher frequencies of marks by the study population were depicted by darker shades for each cell.

 

RESULTS: A total of 34 hands in 26 patients were included in the study. Painful symptoms were clearly centered over the carpal tunnel with a frequency score of 46%. Painful symptoms in the digits were reported less frequently with scores of 23% and 0.3% for the radial and ulnar digits, respectively. Non-painful sensory disturbances (e.g. numbness, paresthesias) were found to have a more peripheral distribution, with the radial three digits demonstrating a score of 60%. Non-painful disturbances were seldom localized to the area over the carpal tunnel (score 12%).

 

DISCUSSION AND CONCLUSION: Our study is the first to compile patient-reported data to establish the normative distribution of symptoms in carpal tunnel syndrome. This represents valuable epidemiologic information that will assist surgeons in making a sound clinical diagnosis, as well as serving as a reference point for the comparison of pre-treatment and post-treatment clinical data.