The value of nerve blocks in the diagnoses and treatment of complex regional pain syndrome type 1: a series of 14 cases

OBJECTIVES

Complex regional pain syndrome type 1 (CRPS-1) can progress to joint stiffness, which may be related to pain and/or capsule-ligament contracture. In this context, it is difficult to distinguish the respective causative roles of pain and contractures. Nerve blocks (NBs) can be used to determine the aetiology of joint stiffness. Subsequent treatment will depend on whether contractures are present or not. The objective of the present study was to evaluate the diagnostic and therapeutic value of the nerve blocks in the management of joint stiffness caused by CRPS-1.

DESIGN OF THE STUDY

A retrospective case series.

METHODS

Implementation of NBs in subjects with joint stiffness caused by CRPS-1. Primary efficacy criterion: an increase in the range of joint movement. Secondary criteria: pain level, treatment decision, duration of therapeutic NBs, return to work.

RESULTS

Fourteen patients with joint stiffness underwent 17 NBs. Ten NBs (59%) were associated with the normalization of the range of joint movement (i.e. the absence of contractures and the presence of an isolated pain component), prompting the implementation of physical therapy during NBs ("therapeutic NBs") in 90% of these cases. Three NBs (18%) were associated with a partial increase in the range of joint movement (i.e. a background of joint stiffness due to a combination of pain and contracture), prompting the implementation of a therapeutic NB in all of these cases. Four NBs (23%) were not associated with any increase in the range of joint movement (i.e. pure contractures), prompting consultation with a surgeon in all of these cases. Forty-three percent of the patients have since returned to work.

CONCLUSIONS

Nerve block is a valuable diagnostic and therapeutic option in the management of joint stiffness caused by CRPS-1.

Influence of preoperative cognitive status on propofol requirement to maintain hypnosis in the elderly

BACKGROUND

The loss of cholinergic neurones in the basal forebrain has been shown to correlate to the extent of cognitive dysfunction during ageing in humans and to the hypnotic potency of propofol in animal models. We examined how the preoperative cognitive status, as assessed by mini-mental state examination (MMSE), may interact with propofol consumption during anaesthesia in the elderly.

METHODS

In a prospective study, we recruited 41 patients (65-99 yr) undergoing surgery for hip fracture. Femoral nerve block was performed for analgesia. Target-controlled infusion of propofol (Schnider's model) was adjusted to the bispectral index within the range 40-60. Multiple linear regression analysis determined whether age, BMI, gender, duration of anaesthesia, and preoperative MMSE score affected the propofol consumption (general linear model, Systat 8.0).

RESULTS

BMI and MMSE score significantly affected the mean value of propofol consumption. A low MMSE score (below 19) was associated with an observed decrease in propofol requirement in patients >65 yr of age. No significant effect of age, gender, and duration of anaesthesia on the propofol consumption was observed.

CONCLUSIONS

Propofol requirement to maintain hypnosis during general anaesthesia appears to decrease with deterioration in the cognitive status in the elderly. We suggest that a cognitive dysfunction linked to a cerebral cholinergic dysfunction may influence the brain sensitivity for propofol in aged patients.

Central cholinergic depletion induced by 192 IgG-saporin alleviates the sedative effects of propofol in rats

We examined the effect of central cholinergic depletion on the sedative potency of propofol in rats. Depletion was produced by intracerebroventricular administration of an immunotoxin specific to cholinergic neurones (192 IgG-Saporin; 2 microg). As a result of this lesion, acetylcholine concentration was reduced by about 40% in the frontoparietal cortex and in the hippocampus but was essentially normal in the striatum and cerebellum. Sedation in rats was assessed as the decrease in locomotor activity. Sedative potency of propofol (30 mg kg(-1) i.p.) was reduced by about 50% in rats who received the injection of 192 IgG-Saporin as compared to controls. These results show that a central cholinergic depletion alleviates the sedative effect of propofol, and indicates that basal forebrain cholinergic neurones might mediate part of the sedative/hypnotic effects of propofol.