Nearly three-quarters of adults with cerebral palsy experience pain as a symptom, a meta-analysis suggests.

“Pain in adults with cerebral palsy: a systematic review and meta-analysis of individual participant data,” the analysis was published in the Annals of Physical and Rehabilitation Medicine.

Many adults with cerebral palsy report (CP) pain due to various risk factors, including alterations in sensory and autonomic functioning due to early brain injury or muscle spasticity. As people with CP age, joint dislocations or contractures, osteoarthritis, and neuropathy may also result in painful secondary conditions.

“In addition … there is growing evidence that psychosocial factors, such as depression, may play a role in developing or perpetuating … pain in people with chronic disabilities,” the researchers wrote.

However, little is known about how to identify and manage pain in this population — published studies estimate pain prevalence ranges from 36% to 82%. It’s also not clear which subgroups of people with CP are most at risk of experiencing pain.

Researchers analyzed data from 15 previously published studies, which were selected after screening 4,584 studies. The included publications were conducted in Europe, West Asia, Australia, and North America between 2000 and 2016. All but one was deemed to be of good methodological quality.

Collectively, the studies included data on 1,243 people with CP (mean age, 34.3), though not all of these were included in each analysis, based on constraints like data availability.

The prevalence of pain among adults with CP was found to be 70%. Among those with pain, the most commonly affected areas were the legs (76%), followed by the neck and back (66%), and the arms (38%). A lot of variation among the different studies was seen regarding both pain overall and pain location.

This variation is probably at least partly attributable to different studies using different tools to measure pain. This “emphasizes the importance of using common outcome measures specific to pain internationally,” the researchers wrote.

Statistical analyses were then done to determine whether pain was more common in certain patient groups. They found that pain was significantly more common in women than in men, with women nearly twice as likely to report pain.

Additionally, people classified under the Gross Motor Function Classification System (GMFCS, measures motor function) as level 2 or level 4 were significantly more likely to have pain than those at level 1.

Individuals classified as GMFCS level 2 walk in most settings, climb stairs holding onto a railing, and may need physical assistance or a handheld mobility device and a wheelchair for long distances. Those classified as GMFCS level 4 can walk for short distances, but require physical assistance or powered mobility in most settings.

These results may be reflective of differences in physical function, the researchers said.

“The increased level of pain in adults with GMFCS level II [2] might be related to the often asymmetric involvement and walking disability with increased biomechanical strain,” they wrote. “Individuals with GMFCS level IV [4] have ‘whole body involvement’ … which might explain the increased pain prevalence in this group.”

Adults at level 3, “a relatively mobile group,” were also found to have a “a high prevalence of leg pain,” which the study attributed to the possibility of bone deformities and unusual walking patterns that put excessive strain on joints like the knee.

Nonetheless, this isn’t totally clear-cut. For example, no significant increased pain risk was found for those with GMFCS level 5, even though these people also have “whole body involvement.” The researchers speculated this could be due to these people receiving more care than those at level 4, or due to communication problems in measuring pain. More research is needed to clarify these findings.

The team also noted a significantly increased risk (over two-fold) of leg pain among people at GMFCS level 3 — who walk using a hand-held device in most indoor settings and use wheeled mobility for long distances — even though this group was not at significantly greater risk of pain overall. They speculated that this could be due to walking differences.

Arm pain was significantly associated with age. People older than 65 were twice as likely to report arm pain as younger individuals. “[O]veruse related to reduced walking ability and using walking aids or a wheelchair may explain this,” the researchers wrote.

This study found that the prevalence of pain among adults with CP is high, which highlights a need for better ways of helping people cope with this symptom.

“The high prevalence of pain in adults with CP indicated by this meta-analysis is a plea for strategies to strengthen health services and scientific research for individuals with this lifelong disability,” the researchers wrote. “There is need for routine clinical follow-up, including screening and treatment of pain in adults with CP.”