Amelioration of frozen gait by tandospirone, a serotonin 1A agonist, in a patient with pure akinesia developing resistance to L-threo-3,4-dihydroxyphenylserine.
A 71-year-old woman presented with severe akinesia, frozen gait, and compromised postural reflexes, without rigidity, tremor, or vertical gaze disturbance. With a working diagnosis of pure akinesia, we administered amantadine (150 mg/d) and L-threo-3,4-dihydroxyphenylserine (DOPS) (600 mg/d), which alleviated her symptoms. When frozen gait recurred 2 months later, we increased the dose of L-threo-DOPS to 900 mg/d and added levodopa (300 mg/d) combined with carbidopa, but this failed to improve the patient's symptoms. We then combined administration of tandospirone, a serotonin (5-HT) 1A agonist with L-threo-DOPS (600 mg/d), resulting in marked clinical improvement. Tandospirone is reported to activate noradrenergic neurons via the 5-HT 1A receptor, which could account for such striking improvement in a patient previously responsive to the noradrenergic precursor L-threo-DOPS given alone.