While periodic limb movements in sleep (PLMS) and restless leg syndrome (RLS) are well-known in Parkinson disease, similar movements during wakefulness are not as well described.
A recent case report described, for the first time, episodes of “periodic limb movements while awake” in patients with Parkinson disease (PD).
While periodic limb movements in sleep (PLMS) and restless leg syndrome (RLS) are well-known in PD, similar movements during wakefulness are not as well described, and this creates a challenge for diagnosis.
Writing in the journal Movement Disorders, the authors said periodic limb movements while awake, or PLMA, is a wearing-off phenomenon in PD and could be categorized as a low-dose dyskinesia, as the 4 patients described in the report responded to dopaminergic treatment.
The involuntary movements of PLMA share similar characteristics with movements observed during sleep, although they most often occur in the transition phase of falling asleep during the night or while resting during the day.
Criteria set by the International Restless Leg Syndrome Study Group (IRLSSG) include the presence of PLMA as a motor sign that supports the diagnosis of RLS.
Most individuals with PLMA have brief leg and foot movements lasting from between 1.5 and 2.5 seconds, typically marked by great toe extension or triple flexion at the ankle, knee, and hip.
For the patients described in the report, movements included:
The researchers said they considered other explanations before arriving at PLMA.
“All four individuals had a good response to dopaminergic medications, which suggested a possible wearing-off manifestation,” they wrote. The patients were not moving voluntarily to ease the discomfort that comes from RLS or akathisia in the off state.
They also ruled out levodopa-induced dyskinesia. The patients did not show sustained, painful postures nor wider, repetitive leg kicking movements.
Idiopathic RLS has been proposed to stem from reduced striatal D2 receptor levels, lower iron levels in the central nervous system, or peripheral factors, such as abnormal vascular flow in the affected limbs; the authors noted that 3 of the 4 patients had an associated axonal neuropathy, which has been previously described in association with RLS.
All 4 patients had a history of PLMS, with similar nighttime movements.
The study had a few limitations. The diagnosis of PLMS was confirmed objectively in 1 patient through the use of polysomnography. The authors also did not conduct an immobilization test, which has been proposed as a potential standard for classifying and grading the severity of PLMA. The diagnosis of PLMA was based on clinical observations and history, the authors said.
AlshimemerI S, DiLuca DG, Olszewska DA, et al. Periodic limb movements whileawake (PLMA) as a manifestation of wearing-off in Parkinson’s disease: a case series and review of the literature. Mov Disord. Published online May 12, 2022. doi:10.1002/mdc3.13487