TECHNIQUES FOR LOCALIZING NEURAL STRUCTURES
Several methods of needle localization have been described, including
facial "pops," elicitation of one or more paresthesias, perivascular or transarterial
injection, electrical stimulation, and field infiltration. More recently, direct
imaging using ultrasonography, fluoroscopy, computed tomography (CT), and magnetic
resonance imaging (MRI) have been used. Although there is no definitive study that
identifies the best method for needle placement, generalities are possible. For
example, elicitation of a paresthesia appears to be equivalent to electrical stimulation.
Success rates and onset times of paresthesia and nerve stimulation techniques are
further improved if multiple injections are performed. Transarterial injection is
variably successful; a two-injection transarterial technique is comparable to single-injection
paresthesia or nerve stimulator approaches. The success rate with a facial pop or
click is variable and may be more reliable in pediatric patients than in adults.
[7]
