After accurate isolation, 126 peripheral nerves were blocked with 2% or 3% phenol solutions in distilled water in 68 patients with severe spasticity of various causes. Seven nerve blocks were repeated. The period of effectiveness ranged from 2 to 743 days, with an average of 308 days. Paresthesia occurred following ten nerve blocks. Gain and loss of voluntary movement following the blocks were observed. Ease, simplicity, safety, therapeutic benefits, and economic advantages of peripheral nerve block with phenol warrant its more widespread use.The ideal means of management of spasticity is a quantitative and long-lasting alleviation of spas¬ ticity in a selected group of muscle fibers, without impairment of sensation and voluntary movement or local or systemic side-effects. Various physical techniques and agents1 are used in the manage¬ ment of spasticity with temporary relief. Local hypothermia of the spinal cord has given prolonged relief.2 Specific pharmacological agents have been widely used with variable results.3 Among various operative techniques, cordectomy, frontal myelotomy, anterior rhizotomy, nerve resection, tendon resection, and tendon transplan¬ tation may be indicated in selected and well-evalu¬ ated cases. Other techniques, eg, posterior rhizoto¬ my and anterior and posterior cordotomy have been found to be of questionable value in the manage¬ ment of spasticity. Chemosurgery has been performed by injecting absolute alcohol intrathecally and at the peripheral nerves. Tardieu and Hariga have used dilute alco¬ hol at the motor points.' Nathan5 and Kelly and Gautier-Smith6 have used phenol solutions intra¬ thecally. Khalili et al7 have used aqueous phenol for peripheral nerve blocks, and Halpern and Meel-huysen8 have used aqueous phenol at motor points in the management of spasticity.Increased gamma motor activity is considered the main cause of spasticity.910 The differential block¬ ing effect of a high dilution of procaine hydro¬ chloride and cocaine on alpha and gamma fibers has been demonstrated.11 In certain patients, volun¬ tary movement has emerged following peripheral nerve blocks with phenol, with no clinical evidence of sensory involvement.7,9 This could be interpreted as being the result of the selective effect of dilute See also page 1152. aqueous phenol on gamma fibers. In other patients, loss of voluntary movement and sensory impair¬ ment have been noticed, which are evidence of the widespread effect.It is the purpose of this paper to review the tech¬ nique of peripheral nerve blocks with phenol solu¬ tions and to summarize our experience to date. The emphasis will be on the complications and side-ef¬ fects of the technique, while its beneficial effects will be briefly reviewed.Technique A direct-current stimulator and a 22-gauge, 2or 3-inch insulated spinal needle are used to locate ac¬ curately the nerve fibers. Collodion, resin, and Tef¬ lon coatings have been used for insulation. The lat¬ ter has been found to be the most satisfactory. The entire shaft of the needle is coated, excep...