The treatment of a shoulder dislocation sustained during an epileptic seizure can be a challenge to the orthopaedic surgeon. Severe drug-resistant epilepsy with multiple seizures may cause repeated dislocations of the shoulder, resulting in damage to the joint capsule and the glenoid. Any attempt at reconstructive surgery of the shoulder requires complete control of the seizures and prevention of dislocations for at least three months following the surgical procedure.
We report our experience with one patient who had recurrent dislocations of the right shoulder due to uncontrollable seizures; we treated this patient with botulinum neurotoxin type A to prevent the dislocations. The patient was informed that data concerning her case would be submitted for publication, and she provided consent. The case report was approved by our institutional review board.
Shoulder dislocations are well-known complications associated with epilepsy. The literature comprises mainly single case reports on this complication, and most of the reported dislocations have been posterior1,2. Some cases of recurrent anterior dislocations following seizures have been reported3,4. These dislocations usually result from trauma or uncontrolled muscle spasms5, but some occur while patients are restrained, particularly if the patient is in the lateral decubitus position6,7. Many patients who sustain shoulder dislocations due to seizures have a large Hill-Sachs lesion or a glenoid rim fracture3.
The treatment of recurrent shoulder dislocations associated with seizures is complicated. Because of the glenoid injury, soft-tissue repairs have a high failure rate, and bone buttress procedures are recommended5. Stabilization and immobilization of the shoulder is necessary until the bone block is fully united. Hutchinson et al.5 reported on a series of fourteen epileptic patients who had recurrent shoulder dislocations. They delayed surgery until the epilepsy was under control and used an anterior bone block to stabilize the glenohumeral joint. None of the thirteen patients who had been followed had a dislocation after this procedure.
Because our patient had uncontrollable seizures and anterior glenohumeral dislocations two or three times a week, she was a poor candidate for surgery. Since neither medications nor vagal stimulation had controlled the epilepsy, we used chemical denervation of the internal rotator muscles with botulinum neurotoxin type A. This is a potent neurotoxin that prevents the release of acetylcholine from the axon to the muscle nerve junction, thus preventing muscle contraction8. It has been used for the treatment of spasticity for more than twenty years, in both pediatric and adult age groups, and has been shown to be safe for patients9.
In the presence of a substantial defect in the anterior part of the glenoid, an uncontrolled contraction of the internal rotator muscles of the shoulder is the main cause of anterior dislocations; therefore, we elected to denervate these muscles before attempting surgery. From clinical observation of patients with voluntary anterior shoulder dislocations, it appears to us that the mechanism of an anterior dislocation during convulsion is a contracture of the external rotator muscles first; while these muscles are still contracted, the subscapularis muscle contracts and pulls the humeral head medially into a dislocated position.
With our patient, we used ultrasound-guided injections, and, although her seizures continued, the shoulder dislocations ceased. During the shoulder reconstructive surgery, we performed a capsular shift and a bone block placement, and injected botulinum neurotoxin type A into the internal rotator muscles under direct vision. The patient continued to have uncontrollable seizures, but the reconstructed shoulder remained located.
In our patient, botulinum neurotoxin type-A injections into the internal rotator muscles of the shoulder were instrumental in preventing dislocations of the shoulder due to seizures; these injections can be used as an adjuvant to immobilization when shoulder capsular reconstruction procedures are performed in patients with epilepsy.