Scapulothoracic dissociation: An emerging high-energy trauma in medical literature.

Scapulothoracic dissociation (STD) is a devastating consequence of high-energy trauma sustained by the shoulder girdle that can easily result in rapid mortality. Since described by Oreck et al. in 1984, STD has been reported in a handful of journals and individual case series, though is still considered a rare occurrence in the context of shoulder injuries. In this report, we examine the case of a 25-year-old female involved in a high-speed rollover auto accident. Unique to this case was the discovery of a completely transected axillary artery and vein with intracorporeal bleeding and complete avulsion of the ipsilateral brachial plexus requiring immediate ligation of the vessels followed by interval above-elbow-amputation and later glenohumeral disarticulation.

INTRODUCTION

Scapulothoracic dissociation (STD) is a rare injury with potentially debilitating consequences.[1] Credited by many for first detailing the lesion in a 1984 case series, Oreck described STD as a complete disruption of the scapulothoracic articulation with lateral scapular displacement and intact skin.[234] STD is characteristically associated with a wide range of musculoskeletal and neurovascular injuries.[1] Patients often present with soft-tissue swelling of the shoulder, lateral displacement of the scapula, injury to bone (an acromioclavicular separation, a displaced clavicular fracture, or a sternoclavicular disruption) and neurovascular injury.[3] Although exceedingly rare, bilateral STD has been reported.[5]

At least 50% of reported STD cases are a result of motorcycle accidents.[2] When thrown from a motorcycle, a rider may reflexively hold onto the handle bar, leading to a distraction/sheer force strong enough to dislocate the acromioclavicular joint or tear the shoulder girdle musculature.[36]

Patients with an STD injury often have poor outcomes, mostly stemming from other associated injuries resulting from the causative high-energy trauma. Flail extremity has been reported in 52% of patients and early amputation required in 21%.[5] Approximately 10% of patients with STD die from their concomitant traumatic injuries rather then STD itself.[5]

The following case describes a 25-year-old female who suffered an STD injury associated with a debilitating head injury; a complete axillary artery, axillary vein, and brachial plexus avulsion with significant blood loss.

CASE REPORT

The presented patient is an intoxicated 25-year-old female who was brought to our trauma bay after an auto collision in which the patient was a restrained driver. On arrival, her Glasgow Coma Scale was four and she required immediate intubation. She was hemodynamically unstable with initial BP of 77/30 and HR 127. She was transfused two units of packed red blood cells. Due to persistent hypotension and multiple injuries, bilateral chest tubes were placed. Initial chest and pelvis radiography revealed left clavicle, left scapula, left humerus fractures along with a left pelvic fracture [Figures 1 and 2]. FAST scan was negative. She had an expanding hematoma over her left shoulder. Her left upper extremity was cold and pulseless with no Doppler signals. She was taken emergently to the operating room.

Figure 1

Initial chest radiograph. Note proximal 1/3 left clavicular fracture in 100% displacement with posteroinferior angulation

Figure 2

Left midshaft humerus fracture

The patient was otherwise healthy prior to the accident with no history of medical problems. She has a history of a Cesarean section 3 years prior and bilateral tubal ligation. She was a nonsmoker who drank occasionally and denies drug use.

Initial laboratory values on admission include the following: white blood cell count 6.3 × 103/mm3, hemoglobin 5.8 g/dL, hematocrit 19.9%, platelets 274 × 103μl, sodium 140 mEq/L, potassium 3.5 mEq/L, chloride 108 mEq/L, carbon dioxide 15 mEq/L, urea nitrogen 10 mg/dL, creatinine 0.9 mg/dL, glucose 255 mg/ dL and blood alcohol level 0.23. She was acidotic, with a pH of 6.98 and carbon dioxide tension 42 mmHg, oxygen tension 258 mmHg, bicarbonate 10 mEq/L and base deficit -20 mEq/L with lactate of 6.8 mmol/L.

The patient was taken to the operating room emergently for surgical exploration. Intraoperative evaluation revealed a left shoulder that was completely dissociated from the musculoskeletal structures and held in place only by overlying skin. Given the continuously expanding left shoulder hematoma; surgical control of the proximal subclavian artery was obtained via a left thoracotomy. Brief examination of the pleural space showed no sign of hemothorax. Once vascular control was obtained the subpectoral space was explored and contained a large hematoma, which was initially packed and later re-explored. The proximal subclavian arterial stump was visualized and avulsed from the axillary portions. The proximal and distal arterial stumps were identified and found to be recoiled in the proximal arm and controlled. The axillary vein was identified and also found to be completely avulsed. Both proximal and distal stumps were clamped. Further dissection and irrigation revealed that the left brachial plexus was completely avulsed, and that only dozens of frayed, stretched filaments remained. Once hemostasis was obtained, a left chest tube was placed and the skin closed.

An exploratory laparotomy was also performed which was grossly negative. In anticipation of a large volume resuscitation requirement, the patient's abdominal fascia was left open, and the abdominal contents contained within a Bogota bag allowing for a future second look.

The patient was then taken to the surgical intensive care unit (SICU) for observation and continued resuscitation.

Once stabilized the patient was taken to the CT scanner to complete the trauma evaluation. She was found to have bilateral parieto-occipital and cerebellar low-density changes consistent with ischemia. A ventriculostomy was placed by neurosurgery; however, due to increasing intracranial pressures, the patient required emergent craniectomy.

On postoperative day number one, the patient was taken back to the operating room for re-exploration of the left shoulder incision. The axillary vessels were hemostatic and no necrotic tissue found. The wound was closed in layers.

Following orthopedic consultation, the left arm was deemed unsalvageable. On postoperative day number two, the left upper extremity was subsequently amputated to the level of the humeral fracture near the deltoid insertion and the abdomen closed. After 5 days of observation in the SICU, the patient was brought back into the OR for amputation revision and glenohumeral disarticulation, in which the distal end of the fractured clavicle and free-floating segment of the left acromion were resected. The remaining brachial plexus components were transected and allowed to retract into their medial stumps, and the left pectoralis major was brought up to the distal end of the medial clavicle to control the bone. Full-thickness skin flaps were raised anteriorly and posteriorly to the level of the glenohumeral joint facilitating a tension free closure.

On hospital day number seven, the patient was considered stable for transfer and taken to her HMO-approved hospital. At the time of this writing she is currently at a skilled nursing facility and requires full care.

DISCUSSION

The above case describes the tragic injuries of a 25-year-old female involved in a rollover motor vehicle accident. This patient presented with the classic findings commonly associated with STD injuries, involving a violent lateral rotational displacement of the shoulder girdle, likely caused by the vehicular rollover. The patient's presentation included massive swelling, palpable hematoma, gross shoulder subluxation, weakness and tenderness highly suggestive of STD.[5]

The diagnosis of STD is based primarily on history, physical exam and radiographic findings.[7] A high index of suspicion for STD must be maintained so that this dangerous injury is not overlooked. Obtaining details of the inciting trauma are of utmost importance. The frequently associated distracting injuries in severely injured patients make this a frequently "missed injury".[2] These patients often present with decreased mental status or require intubation on arrival, which can limit the amount of information obtained from the patient, and further delay the diagnosis.[7] Also, initial chest radiographs are often not properly aligned in a true anteroposterior position, making it difficult to identify the lateral deviation of the scapula, one of the hallmark signs of this condition.[7]

On primary survey, massive soft tissue swelling caused by hematoma and edema may be the only visible signs.[8] Additionally, the patient may present with shoulder instability, tenderness to palpation, pulselessness, weakness and numbness of the upper extremity. A common mistake is to attribute pulselessness to a more distal injury, when in fact a more proximal injury may exist.[5] Frequently, patients will maintain distal pulses due to the extensive collateral network around the shoulder girdle and its protection against limb ischemia.[2]

Diagnosis of STD can be made with an anterior posterior chest radiograph.[456] Lateral displacement of the scapula on a chest radiograph is pathognomonic for STD.[2] The degree of lateralization can be quantified using the scapula-index.[2] The scapula-index is calculated by measuring the distance from vertebral spinous processes to the medial border of the scapula bilaterally and dividing the value of the injured side by the value on the non-injured side.[2] The average scapula index is 1.07 +/- 0.04.[27] When STD is suspected, emergent subclavian, axillary and brachial arteriography is essential to evaluate the vascular structures, especially if the patient has a pulseless upper extremity or is unstable.[268]

In 1977, Damschen described a classification system for STD based on clinical presentation. Type I STD is classified as musculoskeletal injury alone; IIA musculoskeletal injury with vascular disruption; IIB musculoskeletal injury with neurological impairment; and III musculoskeletal injury with neurologic and vascular injury.[245] Zelle et al. studied the functional outcomes of patients with STD. They found in their case series that the presence of a complete brachial plexus avulsion is predictive of a poor functional outcome. Therefore, a fourth type was added to the Damschen classification of STD; those patients with complete brachial plexus avulsion.[27]

Initial management of traumatized patients should focus on cardiopulmonary resuscitation and stabilization of the patient.[17] Given the high likelihood of associated life-threatening injuries with STD, these injuries must first be evaluated. Care must be taken not to overlook a potential STD injury, and in the acute setting, the control of vascular injuries and ischemic complications should be a priority in patients with STD.[7]

Ebraheim et al. proposed a treatment protocol based on three phases of patient management. The acute phase is focused on diagnosis and resuscitation.[5] Vascular injury should prompt immediate surgical intervention with repair performed within 4-6 hours of injury. Autologous saphenous vein graft is the preferred graft; however, PTFE is acceptable if there is a significant size mismatch or prolonged ischemia is present making repair technically difficult.[5] Venous injuries can be ligated in most cases with little consequence, though rare reports of upper extremity edema have been reported.[5]

The subacute phase, 24 hours to 2 weeks after the injury, focuses on management of the sequelae of the initial injury and consideration for amputation.[5] If a complete injury to the brachial plexus exists, a patient may benefit from glenohumeral disarticulation or above-elbow amputation.[5] A zone of demarcation of the skin can determine the level of amputation.[5]

The final phase evaluates nerve injury and considers reconstruction options.

Amputation should be considered for patients where functional recovery is unlikely. In patients where complete brachial plexus avulsion has occurred, a primary above-elbow amputation is preferred.[2] Most authors prefer early amputation with immediate prosthetic fitting. Early-amputation is associated with quicker return to employment and better pain relief.[2] Delay in amputation is associated with myloglobinuria, hyperkalemia, vascular thrombosis, and increased risk for pressure ulcers in the flail extremity.[2] Families are also more likely to refuse amputation if it is suggested late.[7]

The Type IV STD injury that we present above was catastrophic for this patient and led to an upper extremity amputation.

CONCLUSION

Above we present a rare case of Type IV STD. This 25-year-old female suffered complete brachial plexus avulsion and complete arterial and venous vascular compromise. Given the complexity of this patient and the lack of specific guidelines in the literature, this patient was treated with ligation of vascular injuries and a two-staged upper extremity amputation. As increasing numbers of STD injuries present, the body of literature will help clarify the most ideal treatment modalities.