Could the Hanging Drop Technique Be an Alternative Method to Loss of Resistance in Cervical Epidural Injections?

Background: Cervical interlaminar epidural injections are usually performed with the loss-of-resistance (LOR) technique. Therefore, no studies have evaluated or compared the hanging drop (HD) technique with the LOR technique in the administration of cervical interlaminar epidural injections (ILESIs).

Objectives: This study aimed to evaluate the success of the HD technique when used with the LOR technique in cervical ILESIs.

Study design: A prospective, randomized trial.

Setting: Department of Pain Medicine, Ege Hospital, Baku, Azerbaijan.

Methods: After obtaining ethical committee approval and initiating a randomization process, we allocated patients diagnosed with cervical herniated nucleus pulposus (CHNP) into LOR- and HD-method groups. The LOR group comprised 38 patients, and the HD group comprised 41 patients. All patients underwent interlaminar epidural steroid injections under C-arm fluoroscopy in contralateral oblique (CLO) safety view with an initial start angle of approximately 60 degrees. For the LOR group, the procedure was considered successful if there was a loss of pressure after slightly crossing the ventral spinolaminar line (VSLL) and the administered contrast material was in the epidural space. The procedure was considered successful if the saline in the needle's hub fell with negative pressure after slightly passing the VSLL and if the contrast administered was seen in the epidural space with fluoroscopy. In the HD group, there was no sensation of a drop in 3 patients, and the procedure was completed with LOR, so these patients were excluded from the study. Complications and pain scores on the VAS (visual analog scale) were questioned at the time of the procedure and at one hour and 3 weeks after the procedure, and successful injection ratios were recorded.

Results: The LOR and HD groups were similar in age, gender, body mass index (BMI), and side of ILESI. The successful injection ratio was higher in the right- and left-sided ILESI group than in the median ILESI group (P < 0.01). Therefore, no differences were found between the right and left ILESI groups. Binary logistic regression analysis found that age, gender, and BMI were not associated with successful injection in the HD group, while medial injection was associated with decreased successful injection risk (OR: 0.068, P = 0.034). The successful injection ratio was higher in the LOR group than in the HD group (P < 0.001).

Limitations: The study's limitations include the relatively small number of patients with CHNP  and the lack of mention of the level of CHNP.

Conclusions: The LOR technique was superior to the HD for cervical ILESIs. More studies with larger sample sizes may provide more precise and detailed information.