Two Novel Psychomotor Tasks in Idiopathic Normal Pressure Hydrocephalus

Idiopathic normal pressure hydrocephalus (INPH) is a neurological disorder presenting with gait, cognitive, and bladder symptoms in the context of ventricular enlargement. Although gait is the primary indicator for treatment candidacy and outcome, additional monitoring tools are needed. Line Tracing Test (LTT) and Serial Dotting Test (SDT), two psychomotor tasks, have been introduced as potential outcome measures but have not been widely studied. This preliminary study examined whether LTT and SDT are sensitive to motor dysfunction in INPH and determined if accuracy and time are important aspects of performance.

Eighty-four INPH subjects and 36 healthy older adults were administered LTT and SDT. Novel error scoring procedures were developed to make scoring practical and efficient; interclass correlation showed good reliability of scoring procedures for both tasks (0.997; p<.001).

The INPH group demonstrated slower performance on SDT (p<.001) and made a greater number of errors on both tasks (p<.001). Combined Time/Error scores revealed poorer performance in the INPH group for original-LTT (p<.001), modified-LTT (p ≤ .001) and SDT (p<.001).

These findings indicate LTT and SDT may prove useful for monitoring psychomotor skills in INPH. While completion time reflects impaired processing speed, reduced accuracy may suggest planning and self-monitoring difficulties, aspects of executive functioning known to be compromised in INPH. This is the first study to underscore the importance of performance accuracy in INPH and introduce practical/reliable error scoring for these tasks. Future work will establish reliability and validity of these measures and determine their utility as outcome tools.