Research

The following is a list of presentations and selected abstracts presented by the Cerebral Palsy and Neurologic Upper Extremity Service.

Abstracts

Extensor Pollicis Longus Rerouting in the Treatment of Thumb in Palm Deformity in Cerebral Palsy 
Michelle Gerwin Carlson, M.D.; Catherine Brooks OTR, CHT

Objective: To evaluate the results of treatment of thumb in palm deformity by two methods: adductor release alone, and adductor release augmented with rerouting of the extensor pollicis longus (EPL) tendon.

Design: Twenty three cerebral palsy patients were treated for thumb in palm deformity with release of the adductor tendon through a z-plasty in the first webspace. Thirteen of these twenty three patients also had a rerouting procedure performed on the EPL tendon, differently than previously described by Manske et al, in that the tendon was not transected, but rather rerouted in tact. First, it was removed from the third dorsal compartment, allowing it migrate radially, and then a radial pulley was created from a slip of the abductor tendon sewn to the first dorsal compartment to maintain its radial position. In this way traction on the proximal EPL intra-operatively produced abduction of the thumb ray instead of adduction and extension. If hyperextension of the MP joint was noted, a capsulodesis of the MP joint was concurrently performed.

Measurements and Results: Pre- and post-operative measurements of the active and passive first web space were taken.

All EPL tendons could be palpated firing post-operatively.

Conclusion: Rerouting of the EPL in addition to adductor release improves not only the passive but also the active first web angle, with a key component of improvement being radial abduction instead of palmar abduction. This new method of rerouting has three benefits: it is does not necessitate transection of the tendon, fewer adhesions are formed as the extensor hood over the MP joint is not interrupted, and it is more facile than other methods as suturing of the tendon is not necessary.

Acknowledgements: This project was generously supported in part by the Tow Foundation.

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Fractional Lengthening of the Biceps and Brachialis in the treatment of Spastic Elbow Flexion Deformity in Cerebral Palsy 
Michelle Gerwin Carlson, M.D.; Catherine Brooks OTR, CHT

Objective: Elbow spasticity in hemiplegic cerebral palsy is a functional problem affecting the position of rest of the extremity and the active range of motion of the elbow. Often the passive range of motion is full or near full. A complete release at the elbow (Z-lengthening of the biceps, myotomy of the brachialis, release of the brachioradialis, and capsular release) is usually not necessary in these patients, and will leave them unneccesarily weak. The purpose of this study was to evaluate the results of a less radical treatment of fractional lengthening of the biceps and brachialis in the treatment of elbow spasticity in hemiplegic Cerebral Palsy patients.

Design: Ten patients with hemiplegic cerebral palsy and spastic flexion deformities with flexion contractures less than 40 degrees were treated with fractional lengthening of the biceps and brachialis. The average age of the patient at the time of surgery was 12 years. Through a transverse anterior incision, the lacertus fibrosis was transected, then fractional lengthening was performed of the biceps and brachialis with two transverse cuts. Preoperative and postoperative measurements were taken of active and passive elbow flexion and extension as well as the position of rest of the elbow during ambulation. Average follow up was 24 months.

Measurements & Results: Pre-operatively, the patients lacked 21 degrees (range 0 - 45) of passive elbow extension, and 31 degrees (range 20-45) of active elbow extension. The position of the arm during ambulation averaged 91 degrees of flexion (range 70 - 135). Post-operatively the patients lacked 10 degrees (range 0 - 20) of passive elbow extension and 7 degrees (range 0-20) of active elbow extension. The position of the arm during ambulation averaged 49 degrees of flexion. All patients were satisfied with the procedure and felt that the position of the arm was improved. No patient perceived that their elbow was weaker postoperatively.

Conclusion: A population of cerebral palsy hemiplegic patients exist with mild elbow deformities (flexion contractures less than 30 degrees) but with spastic positioning of the elbow during activity of 90 degrees. These patients will benefit from fractional lengthening of the biceps and brachialis to improve the position of rest of the arm during ambulation and other activities without decreasing the strength of flexion.

Acknowledgements: This project was generously supported in part by the Tow Foundation.

Dynamic Elbow Electromyography in Patients with Cerebral Palsy Michelle Gerwin Carlson, M.D.; Catherine Brooks OTR, CHT

Objective: This project used dynamic electromyography to examine the firing characteristics of peri-articular elbow muscles in patients with cerebral palsy.

Design: 20 patients with hemiplegic CP with increased elbow flexion were evaluated with dynamic EMGs at the biceps, brachialis, brachioradialis and triceps. The results were compared to normal elbow EMGs for phasic firing patterns, muscle gradation and associated reactions. Trials included a reference maximum voluntary isometric contraction (MVIC), flexion and extension "on command" and during function (eating), and activity during contralateral arm motion to demonstrate associated reactions.

Measurements & Results: Phasic Firing: Of the 80 muscles, none presented with the described "out of phase" pattern of "off" during expected action and "on" during antagonist action. Muscles were, therefore, described as pathologic if they demonstrated a sustained on signal, a decreased signal or a poorly alternating pattern between flexion and extension. During the functional trial, of the twenty patients tested, the biceps was pathological in thirteen patients, brachialis in fourteen, brachioradialis in eleven and triceps in seven. Gradation: Gradation is the ability to recruit a different amount of activity for the same motion under different contexts. Gradation was assessed by comparing the % of the MVIC used in the “on command” trial to the % of the MVIC used in the functional trial. Patients presented significantly different gradation patterns than normal (p<0.001). Patients recruited overall more activity, especially during function. The bicep most often had decreased grading (18/20 pts).

Associated Reactions: 18 of 20 patients presented associated reactions. No subject in the normative sample demonstrated associated reactions.

Conclusions: Dynamic EMGs can be used in pre-surgical assessment to identify which elbow muscles have pathological characteristics including abnormal phasic firing, decreased gradation and associated reactions. Dynamic EMGs have traditionally been used in the upper extremity only to identify phasic patterns. Evaluating criteria such as muscle grading ability and associated reactions can enable the surgeon to identify additional pathologic characteristics along with phasic patterns in order to more appropriately address increased flexion at the elbow in patients with cerebral palsy.

Acknowledgements: This project was completed with the valuable assistance of the motion analysis laboratory and financially supported by the Tow Foundation.