Introduction

Trans-mediastinal gunshot wounds are infrequent but life-threatening injuries. The course of the projectile and the bullet track is often unpredictable.₁ Multiple diagnostic and therapeutic algorithms exist for work up of these injuries, and the therapeutic interventions are diverse and challenging. Intrathoracic and intravascular migratory foreign bodies are a small but distinctive subgroup of missile injuries. Contrary to popular belief, very few bullets wander. We present one such case who presented with trans-mediastinal migration of bullet which subsequently migrated from left hilum to the right hilum.

Case Report

An 18 year, young male was admitted with alleged history of gunshot injury to chest. He complained of chest pain and difficulty in breathing with decreased air entry on right side of chest. His PR was 98/min and BP was 90 mmHg systolic. There was an entry wound of one cm size on anterior chest wall in the fourth intercostal space on right side, just lateral to the edge of sternum. Chest radiograph revealed a radio-opaque foreign body of metallic density on left side of chest at the level of left hilum with right haemothorax (Fig. 1).

Figure 1

Figure 1: Chest X-ray showing (R) haemothorax and bullet near (L) hilum

A chest tube was inserted on right side with drainage of 350 ml of blood. Contrast enhanced computed tomogram (CECT) of thorax was performed next day, which revealed a 1.5×0.9 cm radio-opaque shadow of metallic density in the left chest adjacent to bronchus intermedius (Fig.2).

Figure 2

Figure 2: : CT thorax showing bullet near bronchus intermedius on (L) side

Though patient became stable after inter-costal drainage, the decision of doing thoracotomy was taken for removal of bullet, since it was present near vital structures. Left thoracotomy was done after five days, in left lateral position. Heart, left lung, bronchi and major vessels were found to be normal, but bullet was not found in the left hemithorax despite thorough exploration. An intraoperative radiograph also failed to reveal the bullet, probably because of poor quality. Postoperative radiograph showed the bullet on right side.

Figure 3

Figure 3 : Postoperative chest radiograph showing bullet on (R) side.

Bronchoscopy was done before discharge of the patient, which was normal and failed to locate the bullet. A follow-up radiograph taken after a week and after six months revealed the bullet to be present on right side in exactly the same position (Fig.3).

Discussion

Gunshot wounds and in particular chest gun shot wounds are becoming a growing problem nowadays. The ones that traverse the mediastinum frequently cause serious injury to the cardiac, vascular, pulmonary, and digestive structures. Most patients present with unstable vitals, however patients with stable vital signs are not infrequent. Work-up of these patients may range from surgical exploration to radiographic and endoscopic testing to mere observation. Nagy et al retrospectively reviewed 50 stable patients of thoracic gunshot wounds and found that 16% patients had mediastinal injury.₂ They concluded that patient may appear stable following a mediastinal gunshot wound, even when they have life-threatening injuries. They advocated continued aggressive work up of these patients to avoid missing an injury with disastrous consequences.₂

The standard work-up of these patients include – Good quality X ray chest, CECT thorax, Bronchoscopy, esophagoscopy or esophagography and mediastinoscopy.₃ Hanpeter et al evaluated the role of helical CT scan in such cases and found that there was a change in the management in 50% of cases on the basis of CT scan.₄ Ibirogba evaluated the efficacy of contrast-enhanced CT scanning in evaluating the potential mediastinal injuries in stable patients with trans-mediastinal gunshot wounds.₅

Wandering bullets are a small but a distinctive group of missile injuries. Cases like intrapericardial tumbling bullet, wandering intraspinal bullet, and intraoperative migration of a foreign body from left bronchus to right bronchus have been described in the literature.₆₇ Pathophysiology of migration depends upon, both missile and tissue characteristics. Crushing of tissues by missile can lead to permanent and temporary cavitation. Permanent cavity is caused by actual tissue damage while temporary cavity is caused by radial stretching of pathways.₈ Kikuchi suggested that shape and chemical nature are also important factors, that may increase the possibility of migration.₉

We think that, in our patient the bullet migrated from left to right side along the cavitation caused by the bullet in the posterior mediastinum. The migration was facilitated by postural changes and muscle relaxants used during general anaesthesia. The following conclusions were drawn from the review of literature and personal experience gained after this case

• Asymptomatic migration of bullet in transmediastinal gunshot wounds is rare but possible.

• Stable patients with mediastinal gunshot wounds should be managed conservatively after proper work-up.

Correspondence to

Dr. Satish Dalal 9J/54, Medical Campus, PGIMS, Rohtak-124001 (Haryana) INDIA Tel. No. +91-1262-213459, Mobile : 09315326802 E-mail : drsatishdalal@rediffmail.com