Effectiveness of femoral nerve selective block in patients with spasticity: Preliminary results

Objectives: To determine if the vastus intermedius nerve can be blocked by using surface coordinates and to measure the effects of selective nerve block on quadriceps spasticity and immediate gait. Design: Case series. Setting: Physical medicine and rehabilitation department of a university hospital. Participants: Twelve patients with hemiplegia disabled by quadriceps overactivity. Intervention: Anesthesic block of the vastus intermedius by using surface coordinates, femoral nerve stimulation before and after block, and surface electrodes recording of the amplitude of the maximum direct motor response of each head of the quadriceps. Main Outcome Measures: Assessment of spasticity, voluntary knee extension velocity, speed of gait, and knee flexion when walking. Results: To be effective, the puncture point (.29 of thigh length and 2cm lateral) had to be slightly modified to 1cm laterally from a point situated at 0.2 of the thigh length. A selective block of the vastus intermedius could not be achieved, but a block of the vastus lateralis was always achieved, twice associated with a block of the vastus intermedius. resulting in decreased quadriceps spasticity, no changes in gait parameters, no decrease in voluntary knee extension velocity, and subjective improvement in gait for 3 patients. Conclusion: Selective block of the vastus lateralis with or without the vastus intermedius can be achieved by using surface coordinates without any dramatic effect on knee extension velocity, and it could be useful for phenol or alcohol block or surgical neurotomy. (C) 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.