Bedside Neuromodulation of Persistent Pain and Allodynia with Caloric Vestibular Stimulation

Biomedicines, 2024 · DOI: 10.3390/biomedicines12102365 · Published: October 16, 2024

Simple Explanation

Caloric vestibular stimulation (CVS) is a technique involving gentle irrigation of cold water into the ear canal to activate the vestibular nerve and brain structures. This study investigates CVS as a potential method to modulate persistent pain and allodynia. The study compared the effects of CVS to an ice pack control procedure in patients with various persistent pain conditions, assessing short-term pain modulation, duration, and repeatability of the effects. The study found that CVS modulated pain relative to an ice pack control. The research suggests that CVS could be a simple, safe, and inexpensive bedside neuromodulation technique for managing persistent pain, warranting further investigation through randomized controlled trials to confirm its clinical efficacy.

Study Duration

Not specified

Participants

38 PP patients (PLP = 8; SCIP = 12; CRPS = 14; non-specific PP = 4)

Evidence Level

Non-randomised single-blinded placebo-controlled study

Key Findings

1
CVS induced a statistically significant pain reduction compared to an ice pack control procedure. Pain reduced from baseline by an average of 24.8% within 30 min after CVS, compared to 6.4% after the ice pack intervention.
2
CRPS patients appeared most responsive to CVS for pain modulation and also exhibited notable cases of allodynia reduction. The durations of pain and allodynia reductions varied from minutes to weeks, and hours to a month, respectively.
3
The study reported that CVS is a well-tolerated intervention, with most patients willing to repeat the procedure if it improved their pain, despite some experiencing discomfort, pain, nausea, or headache.

Research Summary

This study investigated the effects of caloric vestibular stimulation (CVS) on persistent pain (PP) and allodynia in patients with phantom limb pain (PLP), spinal cord injury pain (SCIP), complex regional pain syndrome (CRPS), and non-specific persistent pain (NPP). The study compared CVS to an ice pack control procedure. The results showed that CVS significantly reduced pain compared to the ice pack control within 30 minutes post-intervention. CRPS patients exhibited the most notable responses to CVS for pain and allodynia modulation. The study also found that CVS is a well-tolerated intervention. The authors conclude that CVS warrants further examination for clinical efficacy in managing PP, particularly for pain conditions commonly associated with allodynia. They propose that if therapeutic efficacy is demonstrated in well-controlled studies, CVS could offer a simple, safe, inexpensive, and accessible bedside neuromodulation technique.

Practical Implications

Pain Management

CVS has the potential to be used as a bedside neuromodulation technique for managing persistent pain, offering a non-invasive and cost-effective alternative to other treatments.

Clinical Trials

The results suggest that future research should focus on well-powered randomized controlled trials to exclude placebo effects and sources of bias, particularly for pain conditions associated with allodynia.

Personalized Treatment

Further research may elucidate which PLP and SCIP patients predictably respond to CVS, leading to more targeted and effective personalized treatment strategies.

Study Limitations

1
The study design was convenience-based and non-randomized, involving variability and non-random allocation of intervention order, and was not double-blinded, creating multiple sources of potential bias.
2
The study protocol had variability and non-random allocation of intervention order.
3
The lack of a pain diary to better track longer CVS responses and a lack of standardised outcome measures such as the Brief Pain Inventory.

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