Does cognitive functioning predict chronic pain? Results from a prospective surgical cohort.

It is well established that chronic pain impairs cognition, particularly memory, attention and mental flexibility. Overlaps have been found between the brain regions involved in pain modulation and cognition, including in particular the prefrontal cortex and the anterior cingulate cortex, which are involved in executive function, attention and memory. However, whether cognitive function may predict chronic pain has not been investigated. We addressed this question in surgical patients, because such patients can be followed prospectively and may have no pain before surgery. In this prospective longitudinal study, we investigated the links between executive function, visual memory and attention, as assessed by clinical measurements and the development of chronic pain, its severity and neuropathic symptoms (based on the 'Douleur Neuropathique 4' questionnaire), 6 and 12 months after surgery (total knee arthroplasty for osteoarthritis or breast surgery for cancer). Neuropsychological tests included the Trail-Making Test A and B, and the Rey-Osterrieth Complex Figure copy and immediate recall, which assess cognitive flexibility, visuospatial processing and visual memory. Anxiety, depression and coping strategies were also evaluated. In total, we investigated 189 patients before surgery: 96% were re-evaluated at 6 months, and 88% at 12 months. Multivariate logistic regression (stepwise selection) for the total group of patients indicated that the presence of clinical meaningful pain at 6 and 12 months (pain intensity ≥ 3/10) was predicted by poorer cognitive performance in the Trail Making Test B (P = 0.0009 and 0.02 for pain at 6 and 12 months, respectively), Rey-Osterrieth Complex Figure copy (P = 0.015 and 0.006 for pain at 6 and 12 months, respectively) and recall (P = 0.016 for pain at 12 months), independently of affective variables. Linear regression analyses indicated that impaired scores on these tests predicted pain intensity (P < 0.01) and neuropathic symptoms in patients with pain (P < 0.05), although the strength of the association was less robust for neuropathic symptoms. These results were not affected by the type of surgery or presurgical pain, similar findings being obtained specifically for patients who initially had no pain. In conclusion, these findings support, for the first time, the notion that premorbid limited cognitive flexibility and memory capacities may be linked to the mechanisms of pain chronicity and probably also to its neuropathic quality. This may imply that patients with deficits in executive functioning or memory because of cerebral conditions have a greater risk of pain chronicity after a painful event.

Are psychological predictors of chronic postsurgical pain dependent on the surgical model? A comparison of total knee arthroplasty and breast surgery for cancer.

UNLABELLED: Anxiety, depression, and catastrophizing are generally considered to be predictive of chronic postoperative pain, but this may not be the case after all types of surgery, raising the possibility that the results depend on the surgical model. We assessed the predictive value of these factors for chronic postsurgical pain in 2 different surgical models: total knee arthroplasty for osteoarthritis (89 patients, 65% women, age = 69 ± 9 years, baseline pain intensity = 4.7 ± 2.1) and breast surgery for cancer (100 patients, 100% women, age = 55 ± 12 years, no preoperative pain). Data were collected before surgery, then 2 days and 3 months after surgery. Anxiety, depression, and catastrophizing were measured with the Spielberger State-Trait Anxiety Inventory, Beck Depression Inventory, and Pain Catastrophizing Scale, respectively. Pain was assessed with the Brief Pain Inventory. Neuropathic pain was detected with the DN4 questionnaire. Multivariate logistic regression analyses for the total knee arthroplasty and breast surgery models considered together indicated that the presence of clinically meaningful chronic pain at 3 months (pain intensity ≥3/10) was predicted independently by age (P = .04), pain intensity on day 2 (P = .009), and state anxiety (P = .001). Linear regression models also showed that pain magnification, one of the dimensions of catastrophizing, independently predicted chronic pain intensity (P = .04). These results were not affected by the surgical model or by the neuropathic characteristics of the pain. Thus, state anxiety and pain magnification seem to constitute psychological risk factors for chronic postsurgical pain relevant in all surgical models. PERSPECTIVE: This prospective study performed in patients with total knee arthroplasty or breast surgery for cancer shows that state anxiety, amplification of pain, and acute postoperative pain independently predict postsurgical pain at 3 months and that this does not depend on the surgical model.

Two injections of erythropoietin correct moderate anemia in most patients awaiting orthopedic surgery.

BACKGROUND: The primary objective of this study was to assess the number of erythropoietin (EPO) injections required to reach a hematocrit (Ht) of 40% in moderately anemic patients. The secondary objective was to compare this strategy with autologous blood donation (ABD) in elective orthopedic surgery in terms of red blood cell (RBC) production. STUDY DESIGN AND METHODS: 93 patients with a baseline Ht between 30 and 39% were randomized into two groups the day of the preoperative assessment. In the EPO group, patients received 40,000 UI/week sc until they reached a maximal Ht of 40%. In the ABD group, a RBC pack was collected every week as long as the Ht was above 33%. RESULTS: Two EPO injections were necessary to reach a 40% Ht in 63% of the patients. It was possible to collect two RBC packs in 45% of the patients in the ABD group. Volume of RBC production was significantly higher in the EPO group: 268 +/- 142 mL vs 141 +/- 129 (P = 0.0001). In the EPO group, Ht was significantly higher on days one and three after surgery and at discharge. The energy score was better in the EPO group. In the ABD group, 12.6% patients vs 6.5% in the EPO group received allogeneic transfusion (ns). CONCLUSION: Only two EPO injections were sufficient to reach a Ht of 40% in the majority of patients. Therefore, to improve cost/effectiveness, the number of EPO injections should be related to baseline Ht instead of the four injections recommended in the product monograph.

Severe hypernatremia after hypertonic saline irrigation of hydatid cysts.

IMPLICATIONS: Patients with iatrogenic hypernatremia and serum sodium levels >170 mmol/L either die or sustain severe central nervous system damage. We report the first case of an adult patient who survived an extreme iatrogenic acute hypernatremia (200 mmol/L) resulting from a hypertonic saline irrigation of multiple intraabdominal hydatid cysts. It is a unique report of an intraoperatively developed serum sodium increase without subsequent neurological damage.