A block injection is the term given to anesthetizing a nerve that serves a large area of the jaw usually the lower jaw; that may numb teeth tongue and half of the jaw in that area. Generally it is an injection of a local anesthetic or a neurolytic agent into or near a peripheral nerve a sympathetic nerve plexus or a local pain-sensitive trigger point.

Nerve blocks relieve pain by interrupting pain sensory pathways and preventing them from reaching the brain. A local anesthetic is used to temporarily block the transmission of pain along these pathways. There are two types of sensory pathways; sympathetic nerve plexus and somatosensory nerve. Nerve blocks can be performed as a single injection continuous infusion or nerve destruction.

Besides local anesthetics various other drugs and methods are available including:

· Corticosteroids (triamcinolone depomedrol) are used in conjunction with local anesthetics in nerve blocks when there is an area of inflammation as in acute herniated disc syndrome nerve entrapment syndrome or trigger point pain.

· Opioids (morphine) are infused continuously into the area surrounding the spinal cord (called the epidural space) to control pain in a certain area of your body.

Alcohol or phenol destroys nervous tissues selectively. These agents are used in neurolytic procedures. Cryoanalgesia (freezing) and radiofrequency (heat) are other methods used in nerve destruction.

Side effects of nerve blocking injections are however there are people who have allergic reactions to local anesthetics. In these patients local anesthetics should not be injected. Steroids that are frequently used in nerve blocks can sometimes cause fluid retention increased appetite blood pressure and blood sugar fluctuations and mood swings. The use of morphine or morphine derivatives can cause constipation urinary retention pruritis (itching) nausea and vomiting.