Alcohol injection

In patients with chronic and severe pruritus of the vulva not amenable to steroid cream therapy, denervation of the vulva is often needed to break the vicious cycle of itching, scratching, excoriation, micolacerations, and irritation of cutaneous nerves. Alcohol injection of the vulva gives the patient a temporary period of denervation. Surgical denervation should be reserved for those patients in whom medical therapy and alcohol injection have failed.

Denervation by alcohol injection requires an understanding of the innervation of the vulva.

To prevent microulcerations and infection, care must be taken to inject the 95% alcohol into the subcutaneous space and not the intradermal space.

The purpose of this operation is to temporarily denervate the vulva by injecting alcohol in a systematic fashion that will denervate each of the cutaneous branches of the ilioinguinal, genitofemoral, posterior femoral, and pudendal nerves. This denervation generally lasts 4-6 months.

Physiologic Changes. Denervation of the perineum blocks the awareness of itching, thereby eliminating the need for scratching. Scratching produces microlacerations that become infected, producing more itching and thus, the vicious cycle. By stopping the itching and eliminating the scratching, this procedure allows the perineum to heal during the 4-6 months of denervation.

Points of Caution. The alcohol must be injected subcutaneously, not subcuticularly, or sloughing of the epidermis will occur.

Technique

Innervation of the vulva is shown. To inject each of the cutaneous branches of these nerves, it is necessary to have a system that will allow controlled injection.

The procedure is carried out under general anesthesia. The patient is placed in the dorsal lithotomy position and draped. A 2-0 silk suture that has been dipped in a medicine glass of brilliant green is used to mark off a grid on the vulva. Using the silk suture, vertical lines extending from the mons pubis to the anus are made 1 cm apart across the entire vulva. To complete the grid, the same technique is used to make horizontal lines 1 cm apart.

A tuberculin syringe and several 25-gauge needles are needed to inject systematically 0.1 mL of 95% alcohol at each point of intersection of the grid. It is important to use several needles so that one needle can be left in the last row to identify the last point of injection as one moves to a new row. Without a marker, it is possible to get confused and skip one or more rows, leaving an area of the vulva innervated.

Cessation of itching is immediate. It is not unusual for the patient to develop cellulitis in the perineal area following the procedure; this can be treated with antibiotics.