Case Report

Penetrating Neck trauma causing tracheal rupture, spinal cord injury, and massive pneumocephalus

Abstract

We describe a case in which tracheal, esophageal, and spinal cord injuries associated with massive pneumocephalus were caused by a flying chainsaw segment. To our knowledge, this is the first such case reported in the medical literature. The management challenges inherent in this exceedingly rare combination of injuries are discussed, and a novel theory explaining the possible pathophysiological mechanism that led to pneumocephalus in our patient is put forth.

Penetrating neck wounds typically occur from either Stab injuries or penetrating projectiles. Traumatic aerodigestive injuries requiring operative repair are rare. In one series of 12 789 consecutive trauma patients over an 8-year period, only 12 (0.09%) patients had aerodigestive injuries [1]. In this case report, we describe tracheal, esophageal, and spinal cord injury associated with massive pneumocephalus caused by a flying chainsaw segment. To the best of the authors’ knowledge, this is the first such case reported in the medical literature.

A 43-year old man sustained a lumber accident in which he was hit by a chainsaw segment that became dislodged because of breakage of the chain and shot through the window pane of the harvester the man was sitting on. The chainsaw segment penetrated the worker’s neck, causing tracheal rupture and fracture of the first and second thoracic vertebrae, and entered the Spinal canal. A physician-staffed helicopter was dispatched to the scene. The emergency physician found a dyspneic, cyanotic patient in hemorrhagic shock. The initial Glasgow Coma Score was 13. After a difficult extrication involving rope rescue due to difficult terrain, the patient was intubated using succinylcholine, and fluid resuscitation was started. On arrival at the emergency department of our facility, the neck wound was examined and the ruptured second and third tracheal ring could be palpated. The patient was stabilized, bilateral Chest tubes were inserted due to hemopneumothorax, and plain x-ray and computed tomography (CT) scans according to our polytrauma protocol were performed. The cranial CT scans revealed massive internal and external pneumocephalus. Beam hardening

artifacts caused the border between gray and white matter to look blurred, which initially led to misinterpretation as massive edema. Minimal bilateral parietooccipital and temporal subarachnoid hematoma and cortical contusions were also described. Computed tomography scan of the spine showed small pockets of trapped air in the cervical part of the spinal canal, a fracture of the first and second thoracic vertebrae, and a metallic foreign body and bone fragments in the spinal canal at level T1. Computed tomography images further demonstrated considerable cervical soft-tissue emphysema, especially pronounced in the pretracheal and prevertebral regions, as well as air in the carotid canal without any signs of vessel lesion. Thoracal CT showed moderate bilateral pulmonary contusions, pronounced atelectasis of the left lower and middle lobes, a modest amount of pneumo- mediastinum, and mediastinal shift to the left. The patient underwent emergency surgery in which the chainsaw segment was removed from the epidural space, the tracheal defect was repaired, and an intracranial pressure monitor probe was inserted. There was some bleeding from the thyroid lobe but no major vessels were injured. Owing to the patient’s critical respiratory state caused by massive aspira- tion of blood from the tracheal and thyroid injury, the removal of the bone fragment displacing the myelon to the left at level T1 was not attempted. The pneumocephalus was largely resorbed after 2 days. Under kinetic therapy, oxygenation gradually improved, but weaning was very difficult. At 11 days posttrauma, tracheotomy was performed. Unfortunately, the patient showed incomplete spinal cord injury below C5. On posttrauma day 19, the Neurological examination revealed preserved motor function below C7/8 and preserved sensory function below T1. Intracranial pressure was always in the upper range of normal values. Because of the improvement in neurological function and both the high risk and the difficulty of the procedure, it was decided not to undertake removal of the bone fragment in the spinal canal. The patient was transferred to a secondary care hospital on posttrauma day 20 but was readmitted to our facility a week later because of an esophageal-tracheal fistula, which was directly repaired using a pectoral muscle flap.

The combination of tracheobronchial, esophageal, and spinal cord injury is extremely rare and coupled with its inherent management challenges.

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254.e2 Case Report

Airway management is of paramount importance in penetrating neck injuries. Bleeding within the tight compart- mentalized spaces of the neck may appear quiescent externally but can cause progressive airway compromise and eventual complete obstruction [2]. The airway must be secured before neck swelling is so advanced that endo- tracheal intubation may be impossible. It has been demon- strated that rapid sequence intubation, when performed by physicians with airway expertise, is safe and effective in managing patients with penetrating neck injury who require airway control [3,4].

Delay in diagnosis has been cited as the most important contributor for increased esophageal-related morbidity [5], but early detection of penetrating esophageal injuries remains difficult. Barium swallow, flexible endoscopy, and rigid endoscopy all have sensitivities approaching 90% [6]. In one study, the combination of rigid endoscope and barium swallow found 100% of esophageal injuries [7]. surgical exploration is considered the gold standard for diagnosis of cervical esophageal injuries. In our patient, the fact that parts of the esophagus could not be distinguished on the CT scan was the only indirect sign of a possible rupture. However, no esophageal injury was found on surgical exploration.

There are no reports of unstable Cervical spine injuries in penetrating neck trauma by Stab wounds, and any projectile would need to fracture the cervical vertebrae in 2 columns to create an unstable fracture. Nevertheless, penetrating trauma to the cervical spine can cause severe irreversible injuries [2]. To date, no studies have evaluated the use of steroids in penetrating neck injuries that result in cervical spine injury. Levy et al [8] demonstrated that the administration of methylprednisolone did not significantly improve functional outcomes in patients with gunshot wound injuries to the spine. In one study, methylprednisolone was even associated with impaired improvement in patients with penetrating spine injury [9].

Pneumocephalus is defined as the presence of air within the cranial cavity. It has been reported in traumatic as well as nontraumatic settings. Air within the cranium implies a connection between the central nervous system and the atmosphere, directly or via air-containing structures. Several theories have been put forth to explain the pathophysiolo- gical mechanisms that lead to the development of pneumo- cephalus: air embolism; any dural defect including craniodural, subarachnoid pleural, and subarachnoid med- iastinal fistula; presence of hyperpneumatization or a “weak spot” in the cranial structure in combination with a pressure differential as caused by continuous positive pressure/bag mask ventilation or forceful Valsalva maneuvers [10]. Our patient did not have any major vessel injury; the central venous line was put in after the CT scan showed the massive pneumocephalus; he did not have any previous fractures, tumors, or operations involving the skull base; and there was no dural defect present on surgical exploration. The existence of a patent foramen ovale predisposing to paradox air embolism in combination with positive pressure ventilation

was ruled out by transesophageal echocardiography. We hypothesize that Air travelled along the prevertebral and pretracheal fascial planes and the carotid sheath, passed through the carotid canal, and entered the cavernous sinus. This proposed mechanism is consistent with the CT findings. The fact that the patient remained in a sitting position for a considerable amount of time before he could be extricated from the harvester, in combination with hypotension, likely facilitated air entry into the cavernous sinus. Although it has been reported that the dissection of air along fascial planes following tracheotomy produces pneumomediastinum in an animal model [11], this is the first report of a comparable mechanism leading to pneumocephalus.

Sylvia Archan MD

Department of Anesthesiology and Critical Care

Medical University of Graz 8036 Graz, Austria

E-mail address: [email protected]

Rainer Gumpert MD Department of Trauma Surgery Medical University of Graz 8036 Graz, Austria

doi:10.1016/j.ajem.2009.05.004

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