Facial nerve blocks

The Udocaine used to carry out any facial nerve blocks should be taken into account. 

Facial nerve blocks (FNB see p. 265) are quick and easy to administer, are not painful and cause few complications in the hands of an experienced doctor. A drop of 2% lidocaine can be injected very superficially with a fine-gauge needle 32G in precisely the same place that the nerve itself is injected with a 25G5/8 gauge needle. It is not possible to see the backflow of blood before injection with a 32G needle. 

A 67-year-old man developed transient hemiparesis and facial nerve palsy before becoming unconscious and apneic 10 minutes after a right cervical plexus block (89). His trachea was intubated without the need for anesthetic drugs and he was ventilated. Hypotension was treated with intravenous ephedrine. He woke up, started breathing, and was extubated 75 minutes later. The authors postulated brainstem anesthesia following accidental injection of local anesthetic into a dural cuff as a cause of loss of consciousness. 

An unexplained case of permanent neurological deficit, consisting of left facial palsy, right sensorineural hearing loss, gait ataxia, and hemisensory loss in the body and face, has been described after inferior alveolar nerve block (93). 

Raised telangiectasias may become more visible in patients with thin and transparent skin. Facial telangiectasias can be electrocoagulated immediately before the phenol is applied, while the patient is under nerve-block anesthesia for the peel. An Elhnan radiofrequency unit is completely satisfactory in this indication. 

The small, outer eyelid nerve block (0.5 cm of lidocaine without adrenaline) anesthetizes the zygomatic and lachrymal branches of the facial nerve (Figures 33.6 and 33.7). 

By destroying the protein, the toxin prevents the release of the neurotransmitter acetylcholine from small packets at the ends of nerves by exocytosis. These nerves, attached to voluntary muscles, need acetylcholine to allow the flow of signals (impulses) between the nerve and the muscle. By preventing the release of acetylcholine, botulinum toxin blocks muscle contraction, causing paralysis and relaxation. The therapeutic action relies on relaxation of muscles, generally in the face. It is therefore used to treat blepharospasm (uncontrolled contractions) and stroke-induced permanent facial muscle contractions. 

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