A 24-year-old patient diagnosed with a T8 schwannoma was scheduled to undergo laminectomy
and excision of the tumor. He had no known comorbidities but had a past history of
anterior dislocation of the right shoulder 3 months earlier for which he had undergone
closed reduction without anesthesia. He had no pain or restriction of movements in
the right shoulder, and consent for high risk of repeat shoulder dislocation on prone
positioning was obtained. After placing the standard American Society of Anesthesiologists
monitors and intravenous access, general anesthesia was administered with intravenous
fentanyl (2 µg/kg), propofol (2 mg/kg), and vecuronium (0.1 mg/kg), and the left radial
artery was cannulated. Anesthesia was maintained with sevoflurane (minimum alveolar
concentration [MAC]: 0.8–1.0) with an oxygen-to-air mixture ratio of 1:1. All the
lines were secured; fraction of inspired oxygen (FiO2) was increased to 1.0; equipment like, gel bolsters, arm boards, and foam rests were
kept ready; and all monitors (except invasive blood pressure monitoring) and airway
circuit were disconnected. The patient was turned prone like a log of wood, with special
attention to the right shoulder. After turning the patient prone on the surgical table
with gel-based bolsters placed under the chest and iliac crest, the shoulders were
abducted and carefully rotated with the elbows flexed and arms placed on arm boards.
However, after doing so, there was a limitation of motion of the right shoulder and
asymmetry between the right and left shoulders. An ultrasound (Sonosite Edge ultrasound
system, Japan) examination of the right shoulder was conducted by the anesthetist
and the orthopaedic surgeon, with a curvilinear probe (2- to 5-MHz frequency), at
the right scapular region. It aided the immediate diagnosis of shoulder dislocation
and the dynamic reduction and treatment of the shoulder dislocation in the intraoperative
period. In addition to the ultrasound, a fluoroscopic examination was also done and
both arms were brought to the side of the torso after the right-sided shoulder reduction.
The surgery proceeded in this position and the patient was carefully turned supine
and extubated without any complications.
Patient positioning is crucial during neurosurgical procedures and always requires
good teamwork. Shoulder dislocation is an unusual complication following prone positioning
that is sparsely reported in the literature.[1] Anterior shoulder dislocation can be precipitated in prone position due to the anterior
distribution of the pressure.[1] Anesthesia can further increase the incidence due to the relaxation of the rotator
cuff muscles. Failure to recognize shoulder dislocation can result in limb compartment
syndrome, ischemia, rhabdomyolysis, and myoglobinuria.[2] The patient's arms were positioned on arm boards with the shoulders abducted and
externally rotated, the elbows flexed, and the forearms pronated. Our neurosurgeons
prefer this position for lower thoracic and lumbar spine procedures because the arms
do not get in the way during the fluoroscopic examination of the spine. However, it
can predispose the patient to shoulder dislocation, followed by brachial plexus injury
and arterial impingement.[3] Hence, for patients with a risk factor of shoulder dislocation, both arms can be
positioned by the patient's side with adducted shoulders, extended elbows, and supinated
forearms.[2] It is suggested that a patient who is planned to be positioned with arms extended
overhead should be able to comfortably demonstrate this “surrender position” preoperatively.[4] If a patient is unable to do so due to paresthesia, numbness, or restricted mobility,
the possibility of tucking the adducted arms should be considered. The diagnosis of
anterior dislocation can be made by skillful examination of the shoulder and can be
confirmed with radiological imaging intraoperatively. Interestingly, point-of-care
ultrasound (POCUS) is highly sensitive for confirming the diagnosis and assessing
the success of reduction in real time.[5] The ultrasound examination can be done by standing behind the patient's affected
shoulder in prone position, with the humerus in an adducted position and the elbow
supported inferiorly. A curvilinear probe or a high-frequency linear array probe,
depending on the patient's habitus, is placed in a transverse position parallel and
just inferior to the scapular spine with the probe marker to the patient's left.[5] The probe is then moved laterally till the glenoid and humeral head are visualized.
Anterior and posterior dislocations can be easily distinguished by the relation of
the humeral head to the glenoid fossa on ultrasound on POCUS.[5] Stimson's method and a stepped approach can help reduce dislocated humeral head
in the prone position with continuous gravity-assisted traction and scapular manipulation
without turning the patient supine.[6] In our case, a high degree of suspicion aided with POCUS led to the timely diagnosis
and management of the pathology, thereby averting potentially disastrous clinical
and medicolegal consequences.
