Diphasic Worsening of Freezing of Gait in Parkinson's Disease

Abstract

Background The relationship between freezing of gait (FOG) and levodopa response is complex. Some patients respond, some have no response and in some patients levodopa causes FOG. We present 2 cases demonstrating a diphasic worsening of FOG after levodopa dosing. Cases Two PD patients with FOG were examined during the practically defined off state, the transition from off to on (15 and 22 minutes postdose), and in the full on state (45 and 60 minutes postdose). FOG was measured using Movement Disorder Society–Unified Parkinson's Disease Rating Scale part III, item 11: freezing of gait. Both patients experienced worsening of FOG during the transition followed by improvement during the on state. Case 1 had serum levodopa levels measured. Videos are provided. Conclusions To our knowledge, this diphasic pattern of worsening of FOG has not been previously reported. The cause of this phenomenon is unknown but may relate to an inhibitory action of subthreshold levels of levodopa.

Stepping up to meet the challenge of freezing of gait in Parkinson’s disease

“…Therefore, retrospective chart review may offer a more pragmatic approach (see below). It would seem unlikely that even such an interventional trial would help our understanding of ON FOG, which is a rare phenomenon where there is a worsening of FOG following L-dopa [ 40 ]. Previously, ON FOG has been addressed by kinematic studies in the ON and OFF states during an appropriately rigorous levodopa challenge, including serum levodopa levels [ 41 ], but longitudinal assessments are now required to determine whether OFF FOG evolves into ON FOG (where freezing is seemingly caused by levodopa), ON–OFF FOG (where FOG persists in the ON state) or if they develop and evolve separately.…”