The effects of locally injected triamcinolone on entrapment neuropathy in a rat chronic constriction injury model

Progression From Steroid Injection to Surgery in Carpal Tunnel Syndrome Patients With Concurrent Ulnar Nerve Compression: A Retrospective Analysis

BACKGROUND

Steroid injections are a common treatment option in the management of carpal tunnel syndrome (CTS). This study assesses various prognostic factors for progression to carpal tunnel release (CTR) after a first-time steroid injection for CTS with specific focus on concomitant ulnar nerve compression (UNC).

METHODS

This is a retrospective study of 426 hands with CTS treated with a first-time steroid injection in the Long Island region of New York. The main predictor variable was UNC measured in two analytical models of positive UNC and location of UNC (wrist or elbow). Multivariate logistic regression analyses adjusted for demographic, medical, and CTS-related variables for 2 study outcomes occurring within 1 year: (1) CTR; and (2) steroid reinjection.

RESULTS

Overall progression to CTR within 1 year of steroid injection was 23.0%. Ulnar nerve compression was present in 16.7% of patients and was significantly associated with increased odds for CTR but not with steroid reinjection. These results were further localized to be specific for UNC at the elbow. A moderate or severe result on electrodiagnostic studies was associated with increased odds for CTR. Increased age was associated with slightly increased odds of steroid reinjection while a history of distal radius fracture was associated with decreased odds of steroid reinjection.

CONCLUSIONS

Carpal tunnel syndrome patients with UNC may benefit from earlier definitive treatment with CTR rather than attempting steroid injections, as they are more likely to seek reintervention within 1 year of their initial injection.

Antinociceptive effects of oleuropein in experimental models of neuropathic pain in male rats

Background

The present investigation explored the therapeutic actions of oleuropein along with the possible signaling pathway involved in attenuating neuropathic pain in chronic constriction injury (CCI) and vincristine-induced neuropathic pain in male rats.

Methods

Four loose ligatures were placed around the sciatic nerve to induce CCI, and vincristine (50 μg/kg) was injected for 10 days to develop neuropathic pain. The development of cold allodynia, mechanical allodynia, and mechanical hyperalgesia was assessed using different pain-related behavioral tests. The levels of H₂S, cystathionine-γ-lyase (CSE), cystathionine-β-synthase (CBS), orexin, and nuclear factor erythroid-2-related factor 2 (Nrf2) were measured in the sciatic nerve.

Results

Treatment with oleuropein for 14 days led to significant amelioration of behavioral manifestations of neuropathic pain in two pain models. Moreover, oleuropein restored both CCI and vincristine-induced decreases in H₂S, CSE, CBS, orexin, and Nrf2 levels. Co-administration of suvorexant, an orexin receptor antagonist, significantly counteracted the pain-attenuating actions of oleuropein and Nrf2 levels without modulating H₂S, CSE and CBS.

Conclusions

Oleuropein has therapeutic potential to attenuate the pain manifestations in CCI and vincristine-induced neuropathic pain, possibly by restoring the CSE, CBS, and H₂S, which may subsequently increase the expression of orexin and Nrf2 to ameliorate behavioral manifestations of pain.

The search for translational pain outcomes to refine analgesic development: Where did we come from and where are we going?

Pain measures traditionally used in rodents record mere reflexes evoked by sensory stimuli; the results thus may not fully reflect the human pain phenotype. Alterations in physical and emotional functioning, pain-depressed behaviors and facial pain expressions were recently proposed as additional pain outcomes to provide a more accurate measure of clinical pain in rodents, and hence to potentially enhance analgesic drug development. We aimed to review how preclinical pain assessment has evolved since the development of the tail flick test in 1941, with a particular focus on a critical analysis of some nonstandard pain outcomes, and a consideration of how sex differences may affect the performance of these pain surrogates. We tracked original research articles in Medline for the following periods: 1973-1977, 1983-1987, 1993-1997, 2003-2007, and 2014-2018. We identified 606 research articles about alternative surrogate pain measures, 473 of which were published between 2014 and 2018. This indicates that preclinical pain assessment is moving toward the use of these measures, which may soon become standard procedures in preclinical pain laboratories.

Prevention of Nerve Root Thermal Injury Caused by Bipolar Cauterization Near the Nerve Roots

STUDY DESIGN

This was a controlled, interventional animal study.

OBJECTIVE

This study aimed to investigate the thermal injury of nerve root by cauterization near the nerve root and to identify the prevention or rescue procedure of nerve root injury.

SUMMARY OF BACKGROUND DATA

In spine surgery, bipolar cauterization of epidural venous plexus near the nerve root is an essential procedure to control bleeding. Although a potential risk of neurological thermal damage exists, the underlying mechanism and prevention have not been elucidated.

METHODS

Temperature measurement and histological evaluation after bipolar cauterization near the posterior branch of the nerve root were performed using a rabbit model. Subsequently, the effect of saline irrigation or changing the direction of bipolar forceps to reduce thermal elevation during bipolar cauterization was evaluated. Finally, the effectiveness of locally injected corticosteroid after bipolar cauterization was evaluated.

RESULTS

After bipolar cauterization, temperature of the surrounding site reached 60.9 °C, and 47.8% of the nerves were histologically injured. Using saline irrigation, thermal elevation was significantly suppressed up to 42.7 °C (P < 0.01), and no nerve was histologically injured. When bipolar cauterization was performed in the perpendicular direction, temperature of the surrounding site reached only 40.4 °C (P < 0.01). Locally injected corticosteroid reduced the incidence of nerve injury to 25.0%. However, a significant increase in nerve damage remained compared with the sham group (P < 0.01).

CONCLUSION

Bipolar cauterization near the nerve roots can increase the temperature of nerve roots and cause thermal nerve root injury, despite no accidental direct nerve root injury. Using saline irrigation, or setting bipolar forceps perpendicular to nerve roots, thermal elevation could be suppressed and nerve injury could be prevented. Therefore, it is recommended that surgeons set bipolar forceps perpendicular to nerve roots or use saline irrigation for the prevention of nerve root injury.

LEVEL OF EVIDENCE

N/A.