Psychosocial factors and their significance towards pain: a case study comparing monozygotic twins with AIS after spinal surgery
Filingeri, Domenic Joseph
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INTRODUCTION: Adolescent Idiopathic Scoliosis (AIS) is one of the most common spinal abnormalities in children, affecting 2% to 3% of adolescents in the United States. Its cause remains unclear. Many previous studies conclude that AIS may be caused by a combination of genetic and environmental factors, with very few consistencies. Severe scoliosis is usually treated with corrective surgery, and the etiology of post-surgical pain is even more unclear and has the opportunity to affect the patient well into adulthood. STUDY AIMS: By following a monozygotic twin pair with identical DNA, our retrospective case study can control for genetic disposition, and can look toward other possible causes for the pain the patients experienced. This study attempts to shed light on the complexities of AIS and pain with a focus on environmental and psychosocial factors. CASE PRESENTATION: We present a single pair of monozygotic twins treated for AIS with comparable spinal fusion surgeries performed at a large northeast urban children's hospital. Twin A and Twin B were initially treated with a brace for their scoliosis. Despite bracing, their curves progressed and warranted spinal fusion, with Twin A having a Cobb angle of 53°, and Twin B with 50°. The surgery was conducted simultaneously at the age of 13 by two different orthopedic surgeons. At age 7.5, Twin B was treated for Ebstein's anomaly of the tricuspid valve and significant dysrhythmias. METHODS: After the patients were discharged, a comprehensive retrospective chart review of the patients' pre-op, inpatient, and post-op pain and drug regiment was conducted. The patients were also asked to note their pain as they recovered after discharge. The patients and their mother completed self-report measures of multiple psychosocial variables both before and after surgery through REDCap. A Quantitative Sensory Test (QST) was also performed by the patients to assess their sensory sensitivity and pain thresholds. Mechanical, pressure, and thermal scores were obtained with the use of von Frey hairs, a pressure Algometer, and a Thermode. The QST was administered on the patients' palm/ thenar eminence (distant non-surgical site), and on their lower back (surgical site). The QST results were compared to a previous study's median cohort data, to discern if the patients presented hyper- or hyposensitivity for that particular test. RESULTS: Due to the limitations of case studies, the results presented here should be considered strictly preliminary. Twin B experienced more significant pain during both the acute and chronic recovery phases after surgery, and showed lower sensitivities during most pre-op QST trials. Twin B also scored markedly higher on a number of sub-variables in the psychosocial surveys. A notable correlation was the parent protective measure, indicating that the mother may have been more protective of Twin B. CONCLUSIONS: What is unique to this study is that age, gender, Cobb angle, fusion length, and genetic disposition are all controlled for, allowing us to analyze the patients based on other risk factors. Twin B shows consistently higher pain scores while in the hospital as well as while recovering at home. The parent self-report measures support these findings, showing a slight bias in favor of Twin B in regards to protectiveness, which also coincides with large-scale studies. Although preliminary, it is important not to underestimate the role environmental and psychosocial factors play in post-surgical pain.