INFERIOR
Inferior dislocation of the shoulder is the rarest type, accounting for only 0.5% of all cases of shoulder dislocation. The mechanism of injury is forceful hyperabduction and extension of the shoulder during a fall.
Patients present with the affected arm hyperadducted, flexed at the elbow, with the hand positioned above or behind the head in fixed abduction: a “hands up” position of the affected arm (see illustration). These dislocations are best identified via the transcapular “Y” radiographs. Inferior dislocations are often associated with neurovascular compromise, and there are often related tears of the infraspinatus, supraspinatus, and teres minor muscles.9
ASSOCIATION WITH SEIZURES
Any patient who has had a seizure is subject to a variety of injuries, including lacerations, contusions, long bone and skull fractures, and dislocations. Seizures with a fall are associated with a 20% chance of injury.10
Shaw et al were the first to note that, during an active convulsion, the patient’s shoulder is in adduction, internal rotation, and flexion. This positioning predisposes to injury: With sustained contraction of the surrounding shoulder girdle muscles, the humeral head is forced superiorly and posteriorly against the acromion andmedially against the glenoid fossa. The glenoid fossa is shallow; therefore, the humeral head is forced posteriorly and dislocates.11
Researchers at the Mayo Clinic followed 247 patients who were diagnosed with seizures over nine years; 16% of the cohort experienced seizure-related injuries. Of the seizures recorded, 82% were tonic-clonic seizures. The singular predictive factor for injury was seizure frequency: Patients who had more seizures were more susceptible to injury.12
In an evaluation of outpatients with epilepsy, 25% of recorded seizures involved a fall. Among those who sustained an orthopedic injury, one injury occurred for every 178.6 generalized tonic-clonic seizures (0.6%)—a number that doubled for generalized tonic-clonic seizure associated with a fall (1.2%).10
The collective evidence from these and other studies suggests that patients who have poorly controlled tonic-clonic seizures have a higher incidence of seizures and, therefore, falls and injuries.10,12 In the absence of known trauma, a posterior shoulder dislocation is almost pathognomonic of a seizure. In high-risk populations (ie, individuals who have poorly controlled diabetes or who are experiencing alcohol or drug withdrawal), suspicion for posterior shoulder dislocation should be elevated.8
After evaluation in the ED, the patient immediately underwent a nonsurgical closed reduction of the shoulder and suturing of the laceration. He was admitted overnight for further evaluation and was started on an anticonvulsant (levetiracetam). An orthopedic consult was obtained; the dislocation/fracture was managed conservatively with a sling for immobilization. No surgical intervention was recommended, since the patient had a manageable fracture without neurovascular compromise. He was discharged home within 36 hours and scheduled for follow-up appointments with both the neurologist and orthopedic surgeon.
CONCLUSION
This patient had a seizure with an associated fall; both the laceration and the anterior shoulder dislocation with a humeral fracture were associated with the fall and not with tonic-clonic activity from the seizure. Because injuries vary widely from soft tissue to joint dislocations, with possible axillary nerve and/or artery damage, clinicians must do a comprehensive examination of patients entering the ED who have had seizures. Each injury must be addressed individually.