Parkinson's disease (PD) is a degenerative neurological disease presenting with motor and non-motor signs and symptoms. Approximately 30-50% of the patients experience pain. There is no consensus regarding the mechanisms and classification of pain in PD. This paper reviews current data on the possible mechanisms, classifications, evaluation and potential risk factors for pain in PD. Literature searches were performed to identify clinical trials and reviews covering patho-physiology, classification, type, evaluation and risk factors associated with pain in PD. Pain in PD could be related to pathologic changes in the anatomic structures involved in nociceptive mechanisms. Studies on pain mechanisms have been mostly conducted in animals. The mechanism of pain is complicated and influenced by different factors. There are several methodological differences between the studies trying to classify pain and to characterize its subtypes. Potential risk factors for pain in PD include: age, gender, and duration of the disease. Although pain is one of the non-motor symptoms most frequency experienced by patients, it is often under recognized and inadequately treated in contrast to motor symptoms Multicenter studies are needed that include a large cohort of subjects evaluated in multiple dimensions including pain in order to obtain more data and to allow improved management of pain in patients with PD.

Controversy exists as to whether muscle weakness is present in Parkinson's disease (PD). Computerized literature searches identified clinical trials and reviews about muscular strength assessment in patients with Parkinson's disease, using the following databases: PubMed, Ovid MEDLINE, Ovid EMBASE, the Cochrane Database of Systematic Reviews, Cumulative Index to Nursing and Allied Health Literature, and Physiotherapy Evidence Database. Seventeen articles fulfilled all criteria for selection. These studies suggested that isokinetic muscle strength was decreased in patients with Parkinson's disease and that muscle weakness was not specifically related to tremor or rigidity. Bilateral asymmetrical muscle weakness was present in Parkinson's disease when presenting with clinical unilateral hemiparkinsonism. Recent studies using sensitive mechanical devices have provided evidence that muscle strength is reduced in patients with Parkinson's disease compared with age-matched controls. The specific cause of this weakness is not known. Questions under debate were whether this weakness was of central or peripheral origin and whether it was intrinsic to the disease or a secondary phenomenon.

This study indicates that MS-related fatigue shows an impact on physical, cognitive and emotional aspects in this population.

The results from this study suggest that the axial motor impairments impact on QoL and functional status in patients with PD. Further studies are needed with quantitative devices for axial rigidity assessment to determine the relationship between trunk rigidity in PD patients with higher disease severity and HRQoL scales.

Overweight MS patients evidenced higher depression levels, lower functional capacity, and worse self-rated health status in comparison to normal-weight MS patients. These results suggest that weight control programs should be incorporated into the management of patients with MS.