People with Parkinson’s disease are more likely to develop a disabling postural deformity known as Pisa syndrome if they have more severe axial symptoms — such as difficulty with speech or freezing of gait — and a sleep disorder known as rapid eye movement sleep behavior, a study suggests.
The study, “Predictors of Pisa syndrome in Chinese patients with Parkinson’s disease: A prospective study,” was published in the journal Parkinsonism & Related Disorders.
Pisa syndrome is defined as a lateral bend in the trunk — a tendency to lean far to one side when doing things like standing or walking. Although this syndrome is estimated to affect more than 1 in 10 people with Parkinson’s, it is not clear what clinical features of the disease make an individual with Parkinson’s more likely to develop Pisa syndrome.
Researchers at West China Hospital, Sichuan University, recruited 373 people with Parkinson’s but not Pisa syndrome, and followed them for an average of two and a half years. Over this time, 22 (5.9%) of them developed Pisa syndrome.
They then compared patients’ baseline clinical characteristics (that is, disease factors at the beginning of the study, before the onset of Pisa syndrome) to see what features were more common in those who went on to develop the postural deformity.
They found that patients who developed Pisa syndrome were significantly more likely to have reported more severe axial symptoms at baseline. Axial symptoms are those that tend to occur later in the disease, and to affect the “middle” of the body; these include difficulties with speech and swallowing, balance problems, and frozen gait.
Patients with Pisa syndrome were also significantly more likely to experience rapid eye movement (REM) sleep behavior disorder (RBD). This disorder is characterized by “acting out” dreams during REM or deep sleep; it can include vocalizations and sudden, often violent, limb movement.
Both of these characteristics were further found to be significantly associated with Pisa syndrome in statistical models.
Patients who developed Pisa syndrome were also significantly more likely to report taste- or smell-related non-motor symptoms. But this association did not remain significant in the models.
Other patient characteristics, including cognitive function, also did not significantly associate with Pisa syndrome’s development.
“We found that patients with RBD and more severe axial symptoms are more likely to develop PS [Pisa syndrome],” the researchers concluded.