Penetrating thoracic spinal cord injury with ice pick extending into the aorta. A technical note and review of the literature.

BACKGROUND: Penetrating spinal cord injuries pose a great challenge to both patients and the treating physicians. Although the overall incidence of penetrating spinal cord injury is the highest in the military, the ubiquity of guns in our society continues to make penetrating spinal cord injury prevalent in the civilian population. These types of injuries are particularly complicated because, beyond the trauma to the neural elements and supporting structures, other organs can be affected and a team approach is required for successful treatment. CASE DESCRIPTION: In this report, the authors present a unique case of an ice pick penetrating posteriorly through the spinal canal into the aorta. The described surgical management involved careful consideration and planning to prevent worsening vascular and neurological compromise. Among the challenges faced are neurological compromise, vascular injury, spinal instability, and cerebrospinal fluid leak.
CONCLUSION: To the author's knowledge, this challenging case represents the first description of a successful removal of a penetrating thoracic spinal foreign body that terminated within the lumen of the thoracic aorta.

INTRODUCTION

Penetrating spinal cord injuries pose a great challenge to both patients and the treating physicians. Although the overall incidence of penetrating spinal cord injury is the highest in the military, the ubiquity of guns in our society continues to make penetrating spinal cord injury prevalent in the civilian population. These types of injuries are particularly complicated because, beyond the trauma to the neural elements and supporting structures, other organs can be affected and a team approach is required for successful treatment. Among the challenges faced are neurological compromise, vascular injury, spinal instability and cerebrospinal fluid (CSF) leak; the latter has been shown to be as high as 36% in patients status after removal of the penetrating foreign bodies.[18] In this report, the authors present a unique case of an ice pick penetrating posteriorly through the spinal canal into the aorta. The described surgical management involved careful consideration and planning to prevent worsening vascular and neurological compromise. To the author’s knowledge, this challenging case represents the first description of a successful removal from this location.

CASE PRESENTATION

A 34-year-old male presented as a trauma after he was assaulted with an ice pick. On presentation, he was an American Spinal Injury Association (ASIA) score C; the motor exam of the lower extremities demonstrated full strength in the right leg and weakness in the left leg; based on the MRC scale, the patient was 2/5 in the proximal and 3/5 in the distal muscle groups. His bowel and bladder function and sensation to light touch and pinprick remained intact. There was a small skin puncture site slightly asymmetric to the right in the lower thoracic spine that was identified as the entry point. A computed tomography (CT) scan demonstrated an 8 cm hyperdense foreign body, consistent with an ice pick fragment, entering the right T10 lamina with an upward and medial trajectory [Figure 1]. The foreign body then traversed the spinal canal and thoracic spinal cord, penetrated the T9 thoracic vertebral, entered the left chest cavity, and perforated the descending thoracic aorta [Figure 2].

Figure 1

Sagittal computed tomography with contrast of the thorax demonstrating an 8 cm linear foreign body extending through the spinal canal and terminating in the lumen of the descending thoracic aorta

Figure 2

Axial computed tomography angiogram of the thorax demonstrating an 8 cm linear foreign body extending through the spinal canal and terminating in the lumen of the descending thoracic aorta. Also note a left hemothorax

Given the patient’s neurologic status and concern for worsening vascular injury, a decision was made to take the patient to the operating room to repair the breach in the aorta and remove the retained ice pick. A multidisciplinary team consisting of neurosurgery, vascular surgery, and cardiothoracic surgery was formed, and the treatment plan consisted of endovascular repair of the aortic injury and removal of the ice pick from the aorta. The patient was positioned in a “lazy” left lateral decubitus position to allow access to the groins and the back. Although the foreign body was eccentric to the right, placing the position on the left would allow the cardiothoracic surgeons access to the aorta, in the event an endovascular solution was unsuccessful. Vascular surgery first gained bilateral access to the common femoral arteries under ultrasound guidance. A thoracic pigtail catheter was placed from the right side to image the descending thoracic aorta. A 12-French sheath was placed in the left common femoral artery in preparation for occlusion of the thoracic aorta with a Coda balloon if the patient became hemodynamically unstable. The aorta was measured and sized using the previous CT of the chest and a Cook TX2 28 × 80 mm graft was deemed appropriate for the repair of the aorta. First, an aortogram was performed via the pigtail catheter that showed no active extravasation of contrast from the entry site. The endograft was then advanced from the left side and positioned at T9. Once the endograft was in place, neurosurgery began exposing the foreign body. A paramedian incision that incorporated the entry site was made and the tract of the foreign body was followed to the spinous process of T10. A subperiosteal dissection was done and the foreign body was localized at its entry point in to the lamina medial to the spinous process. A circumferential exposure required drilling of the surrounding bone structures to optimize access to the foreign body. The distal end of the ice pick was then removed with a large thoracic sternal needle driver [Figure 3]. As the foreign body was removed, the vascular surgery team deployed the thoracic stent graft. A completion angiogram of the descending thoracic aorta was performed which showed no evidence of extravasation or endoleak.

Figure 3

The 8 cm foreign body identified to be an ice pick

After securing the aortic injury, we examined the entry point of the ice pick. CSF was leaking posteriorly through the lamina with Valsalva maneuvers. A fat graft and fibrin sealant were placed over the defect. Special care was taken to minimize the dead space during the closure of the muscle and fascial layers. A lumbar drain was placed at the L4/L5 interspace with caution not to engage the level of the spinal cord injury with the catheter. A chest tube was placed by CT surgery to address the hemothorax; however, the chest tube was purposefully left closed for a few hours before the drainage was started to avoid creating an anterior CSF fistula. The patient was extubated on postoperative day 1, with improvement of his neurological examination (4/5 in all muscle groups of the left lower extremity). The lumbar drain was clamped 48 hours postoperatively and was removed after verifying that there was no leak from the incision site posteriorly. The patient had an uncomplicated hospital stay and was discharged on postoperative day 6 with a normal motor exam except for the left extensor hallucis longus and dorsiflexion at 5-/5.

DISCUSSION

The overall mortality of penetrating spinal cord injury in the military has been on the decline; during World War I, the mortality rate was 71.8% whereas by the end of the Vietnam War the rate had decreased to 2.3%.[69] However, the high incidence of non-military use of fire arms in the United States, make these types of injuries common place in emergency rooms across the United States. Eighty four percent of the victims were men and the National Spinal Cord Injury Database had a mean age of 29.7 years for victims of penetrating spinal cord injury.[1416] The management of these injuries can vary. In a series performed by the US Military, laminectomy was advocated for patients with an incomplete spinal cord injury.[8] Conservative management of penetrating spinal cord injuries was described by Lipschitz and Block among 130 patients with penetrating injuries.[10] In their series, 27% of patients were discharged with complete recovery and returned to their prior occupations without having had any surgical intervention.[10] Moreover, 53% of patients who underwent conservative management after spinal cord injury had a partial recovery and were able to obtain employment.[10] According to Harrington et al., approximately one-third of the patients who suffered from penetrating trauma to the spine remained paraplegic.[3]

In our case, the foreign body was an ice pick which was 3.8 cm deep from the skin, adjacent to the T10 spinous process. Although the patient had an incomplete spinal cord injury, a laminectomy was not performed. The authors believed that the foreign body could be accessed and retrieved without removing the lamina. Furthermore, care was taken to minimize the tissue dissection to minimize the dead space for potential CSF collections. The need to surgically explore the trauma site of a penetrating injury remains controversial. While the basis to intervene largely depends on the patient’s hemodynamic status and neurological function, there are other factors that may compel surgeons to surgically explore. Gulamhuseinwala et al. described such factors as CSF leak and extrinsic cord compression to help guide management.[5] If an intervention is indicated, the timing of the intervention may have clinical consequences. Manzone et al. retrospectively reported that early extraction of a foreign body in penetrating spinal injury may reduce incidences of myelopathy, infection, and delayed neurological deficits.[11]

Imaging studies are necessary to appropriately assess and manage instances of penetrating spinal cord injury. Careful consideration must be made using X-ray/CT or CT myelogram. Any unidentified ferromagnetic fragments may pose additional risk to the patient, and the risk of an MRI needs to be assessed.[13] Furthermore, foreign bodies may be occult on X-ray/CT and MRI. Gul et al. described a case of a wooden foreign body penetrating the spine that had characteristics which probably made identification difficult.[4]

In penetrating spinal injuries with associated CSF leaks, it is advisable to promptly start broad spectrum antibiotics to prevent meningitis.[18] In the present case, broad spectrum antibiotics were administered for 72 hours, until the lumbar drain was removed and there was no concern for CSF leak. Thakur et al. retrospectively described a meningitis rate of 18% in non-missile penetrating spinal cord injury.[18] If the CSF leak is persistent or a CSF fistula has formed, surgical exploration may be warranted.[8]

The use of steroids (methylprednisolone) in patients with penetrating spinal cord injury have been shown to have an adverse outcome in the National Acute Spinal Cord Injury II trial,[15] and were not used in this case.

An injury to the thoracic aorta by any etiology can be fatal due to the immediate massive hemorrhage in the mediastinal and intrathoracic cavity.[1] We debated whether to proceed with an open or an endovascular approach to repair the defect in the aorta. However, balloon occlusion of the proximal aorta prior to the removal of the penetrating ice pick substantially decreased the risk for massive hemorrhage.[1] Furthermore, according to Xenos et al., endovascular repair of the thoracic aorta appears to have lower mortality compared to an open approach. Specifically, spinal cord ischemia is less likely with a minimally invasive endovascular approach.[19] The primary comparison between open and endovascular therapy involved in the analysis was repair of a descending thoracic aortic aneurysms.[19] In concert with endovascular techniques decreasing spinal cord morbidity, lumbar drainage has also been shown to reduce the potential for cord ischemia.[2] Of concern during thoracolumbar injury is the artery of Adamkiewicz. This important branch of the aorta supplies the lower two-thirds of the spinal cord through the anterior spinal artery.[17] The artery of Adamkiewicz is found 73% of the time between T8 and T10.[12] In the present case, the penetrating injury occurred at T9-T10, which was statistically in proximity to the artery of Adamkiewicz. Prior to the endovascular deployment of the endograft, an angiogram was performed to help visualize and avoid occlusion of the artery of Adamkiewicz, as described by Kamada et al.[7] With this is mind, the endograft was safely deployed with no changes in neurological monitoring. After the foreign body was removed, neurophysiological monitoring was also helpful in surveying a possible compression from an intraspinal, subdural, or epidural hematoma. Upon successful extubation, the patient was followed clinically very closely. The patient was admitted to the intensive care unit for hourly neurological checks to assess a possible neurological decline secondary to a compressive hematoma.

CONCLUSION

The mortality and morbidity from penetrating spinal cord injury remains a challenging and difficult to treat condition in trauma patients. This case illustrates how advancement in endovascular treatment minimizes the surgical trauma to the patient and allows for a safe and successful removal of an otherwise potentially fatal problem. The optimal treatment strategy is often assessed on a case-by-case basis and most often requires a multidisciplinary team approach.

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Conflicts of interest

There are no conflicts of interest.