Bilateral Posterior Fracture-Dislocation Of The Shoulder As A Presentation Of An Intracranial Tumor

摘要

Bilateral posterior-fracture dislocations of the shoulder are pathognomonic for seizure induced injuries. Patients that have not been diagnosed with a seizure disorder will often present with nocturnal injuries and no history of trauma. The allusive nature of this injury is compounded by mild presenting signs and symptoms and possible autoreduction with subsequent seizures. Therefore, a high degree of suspicion must be maintained for a seizure disorder as the cause for nocturnal injuries or posterior dislocations at the glenohumeral joint. Among the various causes of seizure disorders, we present a case in which a bilateral posterior-fracture dislocation served as a presenting sign of an intracranial tumor. Introduction Bilateral posterior fracture-dislocations of the shoulder are uncommon orthopedic injuries virtually pathognomonic for convulsion related trauma. The mechanism of trauma can be attributed to an adducted and internally rotated state. Convulsions due to seizures or electrocutions exploit the inherent muscular imbalance between the strong internal rotators (teres major, subscapularis, and pectoralis muscles) and the relatively weaker external rotators (infraspinatus and teres minor muscles).A few cases have been reported in which a nocturnal fracture has been the presenting feature of unrecognized epileptic seizures. One such case, by Aboukasm et al, illustrates a patient who awoke with severe midback pain. The work-up revealed an undiagnosed epilepsy as the cause of the fracture.1 Similarly, another case by Rupprech et al, depicted a patient with a double throracic, humerus, and scapula fracture with an unrecognized cerebral astrocytoma which caused a tonic-clonic seizure.2 Therefore, it is imperative to assess the possibility of an epileptic seizure as the cause of trauma in nocturnal idiopathic injuries. Patients who present with a nocturnal occurrence of posterior fracture-dislocation will not recall any recent trauma and the mild physical findings can make this diagnosis allusive. The importance of an axillary view or a scapular Y view is stressed to assess the glenohumeral joint when a seizure-induced injury is suspected and when there is marked limitation in external rotation and forward flexion at the glenohumeral joint. As suggested, a high degree of suspicion must be present when dealing with an injury related to a nocturnal convulsive episode. Case Report A 62-year-old right-handed man presented to his primary care physician with complaints of right shoulder pain after awaking with no known injuries. He denied any recent falls, traumas, and lifting injuries. Initial exam demonstrated a displacement of the biceps muscle and ecchymosis in the axillary fold. Initially, he had noticed quite a bit of pain and swelling which progressed to weakness, limited ROM, and ecchymosis overlying the anterior and axillary region of his right upper extremity.On examination, there was a considerable loss of passive ROM and pain in forward flexion and abduction past 30° at the right glenohumeral joint. His right elbow flexion/extension arc was also limited and painful. He complained of pain with passive pronation and restricted supination. Grossly, pulses were 2+ and there were no neurologic deficits noted. Radiographs of the right shoulder, AP (Figure 1) and axillary (Figure 2), revealed a fracture-dislocation through the anatomical neck of the proximal humerus as well as comminution around the proximal metaphyseal region. Due to the non-traumatic nature of this injury, an MRI was scheduled to determine the possibility of a tumor and to assess the biceps muscle. The MRI displayed the biceps tendon to be medially subluxated and the marrow pattern did not appear to be consistent with necrosis or tumor.