A comparative, open-label, randomised study; evaluating efficacy of a hand-held device using a combination of vibration and cold, versus only vibration; in reducing the pain sensation of multiple local anaesthesia injections during hair transplant

INTRODUCTION

Pain is a commonly defined limiting factor from a patient's point of view when it comes to common trichology procedures, including platelet-rich plasma therapy and hair transplants, which involve multiple pricks via needle to the scalp. Physicians always try to reduce the extent of this pain felt by patients, using various pharmacological and non-pharmacological measures. Many pharmacological agents, most commonly topical anesthetics including EMLA™, Elamax™, liposome-encapsulated lidocaine cream, amethocaine, cetacaine, and benzocaine products, are being used to reduce the pain of these procedures.^[1]

Although local anesthesia is sufficient for many dermatologic procedures, it may still be ineffective for pain reduction in quite a few procedures. Also, administration of local anesthetic creams may cause high discomfort in some patients^[2], especially if multiple needle pricks are required for local anesthesia. Much research has been devoted to the development of effective topical anesthetics and to scrutinizing their efficacy in reducing procedure-induced pain.^[1,3]

In spite of that, topical anesthetic application does not provide sufficient pain relief practically, is time-consuming, and may cause a variety of complications, such as allergic reactions and toxicities.^[4,5]

EMLA™, for example, is associated with extensive corneal de-epithelialization,^[6] purpura and petechiae^[7-9], and even methemoglobinemia in a few patients if applied to large areas.^[10-12]

Quite a few non-pharmacological modalities are also being routinely used for pain reduction, including vibration devices, cold application, hand holding, and talking to distract the patient (so-called talkesthesia); they find much favor with the treating physician. Although talkesthesia for painful procedures is helpful, alone, it often is insufficient.^[13]

Patients may opt out of a beneficial treatment just because of the pain element. Hence, any intervention that may reduce pain is always an asset. With this in mind, we decided to evaluate the effectiveness of a novel vibrating and cooling device, Leniwand (manufacturer), versus only vibration in reducing the pain sensation of local anesthesia injections during hair transplant surgery.

The gate control theory by Melzack and Wall helps to understand how non-pharmacological modalities of vibration and cooling may reduce the perception of pain.^[14,15]

The application of vibration has long been used for pain reduction, due to neurophysiological effects as well as placebo effects. According to gate control theory, A-β nerve fibers, which transmit information from vibration receptors (Pacinian corpuscles and Meissner corpuscles) and touch receptors in the skin, stimulate inhibitory interneurons in the spinal cord that in turn act to reduce the amount of pain signal transmitted by A-δ and C fibers from the skin to second-order neurons that cross the midline of the spinal cord and then ascend to the brain.^[16,17]

Regarding the treatment of pain by vibration, a Lancet editorial concludes that the use of vibration is "simple, safe, and highly effective and has the added advantage of being cheap to establish and maintain, even in dermatological procedures.^[18,1]

On the other hand, the use of cold to relieve pain has been employed since Hippocrates in the 4th century BC.^[19] Cooling the tissue also induces vasoconstriction, which may decrease swelling and ecchymosis.^[20]

Prolonged cold application (30–60 s) can stimulate the C nociceptive fibers and block the A-delta pain transmission signal when applied close to the nociception source.^[21]

The stimulation of C fibers by cold application also transmits slow pain and noxious thermal information to the brain in activating a supraspinal modulation, which increases the body’s overall pain threshold and therefore produces a generalized hypoalgesia at the insertion site.^[22,23]

MATERIAL AND METHODS

The Leniwand vibratory cooling device used in this study has an outer body shell made with surgical-grade stainless steel. The two principal parts of the device are: the hand-held vibrator and the cuboid stainless steel cooling cube. The cooling cube is filled with a coolant solution. These two separate parts can easily be detached and attached with a simple screw mechanism.

The coolant-filled stainless steel cube is pre-cooled inside the freezer compartment of the refrigerator (-18°C approximately) for a minimum of 2 hours. During the procedure, the cooling device is removed from the freezer and attached to the vibratory part. This assembled device can easily be held in one hand, as seen in [Figure 1]

Close

Figure 1:

Leniwand hand-held single device, which uses both cold and vibration together and helps in pain reduction of injectables. It has a front globular part, which is filled with coolant and is removable, and a back vibrating part. The device is made of stainless steel and is easily cleanable.

Export to PPT

A total of 30 male patients aged 27 to 51 years undergoing 1% lignocaine local anesthesia injections for frontal to mid-scalp hair implantation surgery were included in the study. Allergies to lignocaine or other components of local anesthesia, local site infection, systemic illness, and patients with chronic pain conditions or taking painkiller medications were excluded.

The device was switched on, kept in contact with the skin surface for 30 seconds prior to injection of local anesthetic, with the needle tip insertion point being as close to the cold vibrating part of the device as possible. The anesthesia on one side, starting centrally at the forehead midpoint on the frontal scalp and moving laterally to the temporal area, was administered along with the precooled Leniwand cold vibrating device. On the contralateral side, the same process was repeated with the same non-cooled Leniwand vibrating at the same rotations per minute, but at room temperature. For standardization, the same operator holds the Leniwand vibratory cooling device in the nondominant hand and injects with the dominant hand in all patients in the study. All local anesthesia injections with 1 % lignocaine using 31 G insulin syringes of the same brand (Benet Dickinson). Only one syringe per side and changed to a fresh syringe when changing sides; again, done for standardization. The side to be injected using the Leniwand vibratory cooling device, and only vibration was randomly selected. Using the same Leniwand vibrating devices with the same material and dimensions (one side cooled vs the other side at room temperature) on either side again helped further reduce variance. An eleven-point numeric rating scale NRS (0-10) was used to determine the pain score on either side. The NRS is an 11-point scale on which “0” indicates no pain and “10” indicates the worst pain imaginable [Figure 2]. It was selected because it is both accurate and easy to use. For general purposes, the numeric rating scale has good sensitivity and generates data that can be statistically analyzed for audit purposes.^[24]

Close

Figure 2:

11-point NRS pain scale from 0-10, where 0 indicates no pain, and 10 indicates the worst pain imaginable. NRS is a widely used, straightforward method to assess the pain levels experienced by patients, clinically, quickly. NRS: numeric rating scale

Export to PPT

As this was a split scalp study, a verbal response scale was designed where the patients were verbally asked as a direct comparison which side felt less painful; with responses being noticeably less pain, slightly less pain, no difference, slightly more pain, and noticeably more pain. The control and study sites were assigned within the same patient to rule out bias from individual variations in pain perception, and the study was open-label since it was not possible to blind the patients due to the nature of the device being tested.

RESULTS

In this split scalp study, the following results were observed. Seventeen patients reported a noticeable reduction in pain sensation on the vibratory cooling device side; a further 7 reported a slight reduction in pain on the vibratory cooling side; 5 reported almost no perceptible difference on either side; and one patient reported more pain on the vibratory cooling side. The results are shown in Figure 3 below:

Close

Figure 3:

Patients where both cooling and vibration was used (blue bars) experienced less pain as compared to patients where only vibration was used (red bars).

Export to PPT

DISCUSSION

Pain is a significant surgical problem; 75% of surgical patients experience pain before, during, or after procedures.^[25]

Cooling and vibration are effective in reducing the pain sensation. A number of studies provide evidence that cooling alone or vibration used standalone is effective in reducing the pain sensation of injection.^[26-29]

In this study, the Leniwand vibratory cooling device was found to reduce the pain sensation significantly more compared to vibration alone for local anesthesia injections in hair transplant surgery.

The Leni wand device with a surgical-grade stainless steel body can be easily and quickly disinfected. Such properties in a device may be of particular benefit for a wider acceptance in healthcare.^[30-34]

Studies indicate that the application of cold before and after injection helps reduce pain, erythema, and swelling.^[35,36] Also, cold application reduces the chances of developing ecchymosis and helps in faster resolution of ecchymosis.^[37]

Cooling the treatment area with a firm pressure application with Leni wand post-injection or at the end of the procedure may help reduce the pain, inflammation, erythema, or swelling that can develop post-procedure (PRP injections, Botulinum Toxin, fillers, and laser or energy therapies) on the face, where such a cooling effect is desired. Leniwand device is versatile, can be used only in cooling mode or vibration only mode, or combination mode as desired.

Maximizing patient comfort is an important consideration for all procedures, especially elective aesthetic procedures. Anticipated injection pain has been shown to be a factor in delaying BTX-A treatments for naïve and repeat patients.^[38] A survey of cosmetic patients revealed that concerns about procedure discomfort rated third in importance to surgical result and physician communication.^[39]

Leniwand vibratory cooling device has been used by authors in regular practice during intra-lesional therapy, PRP injections on the face and scalp. There have been no long-term side effects. Some patients do complain of cold and numbness immediately post-procedure, but this is a temporary phenomenon. Also, a few patients find the vibration feeling and noise annoying or unpleasant, but this may be beneficial as a distraction mechanism for reducing the pain sensation.

Combining vibration and cooling, Leniwand's vibratory cooling device is an easy-to-use, single-handed, inexpensive, and fast-acting solution for reducing procedural pain.

Due to its non-pharmacological action, it has no major side effects. Its quick assembly prior to the procedure doesn't require much time. All this increases acceptance of the device for the treating physician.

It helps reduce the fear of the needle and pain in the patient's mind, which is a major hindrance for patients opting out of cosmetic or office procedures.

LIMITATIONS

All the patients in the study were male; this was a selection bias, as most hair transplant procedures in our practice are performed on males.

CONCLUSION

The Leniwand vibratory cooling device has the potential to provide better pain relief for injections compared to just plain vibratory devices. The limitations of the study were that all participants were male patients, the sample size was small, and it was open-label, so some bias is possible. Larger multi-center trials with blinded assessors can be taken up to validate these findings.

This device provides a non-invasive, fast, reusable, easy-to-use solution for injection pain and has a wide variety of potential clinical and health care indications, including all types of injections, office cosmetic procedures, vaccinations, and self-injectors like those used by people with diabetes for insulin.