The gasserian ganglion lies inside the skull on each side of the head. From the ganglion, the trigeminal nerve separates into three branches.

The ophthalmic branch supplies the forehead. The maxillary branch supplies the midface or maxilla. The mandibular branch supplies the mandible or lower face.

A gasserian ganglion block is performed if the desire is to make the face numb. By placing local anesthetic (novocaine) around the gasserian ganglion, the patient should feel numbness in the face. This may help determine if the facial pain they are feeling can be reduced.

If a balloon gangliolysis is performed, the desire is to permanently reduce the facial pain by having a balloon compress the ganglion for 1 minute. A needle with a balloon attached to it is introduced to the region of the ganglion, the balloon is inflated for one minute and then collapsed and withdrawn. This will produce some mild numbness in the region of the face.

A gasserian ganglion block is used to treat trigeminal neuralgia, a form of neuropathic face pain. The condition is described as an intermittent, sharp, electric pain, lasting seconds to minutes and triggered by trivial stimuli such as talking, eating, shaving, brushing the teeth, and washing the face. The pain is limited to one or more of the branches of the trigeminal nerve.

A very fine needle is used for the nerve block. Relief from the pain is usually felt rather quickly.