Ten self-inflicted intracranial penetrating nail gun injuries

Discussion

With the growing use of pneumatic nail guns both in the construction industry and by home consumers, penetrating craniofacial injuries caused by these devices are on the rise. Most of these injuries are primarily work related accident,2-4 but they are also well-reported as intentionally self-inflicted.5 Preoperative evaluation should always include thin cut CT scans allowing for multiplanar reconstruction. In addition, assessment of the cerebral vasculature is prudent especially if the nail appears to traverse a major vessel although the incidence of vascular injury secondary to nail gun injury is low. Trauma to the cerebrovascular system has been associated with a wide variety of pathologic consequences including: arterial dissection, pseudoaneurysm, arteriovenous fistula, arterial or venous rupture or thrombosis,6 vessel perforations, carotid-cavernous fistula, and even fatal epistaxis.2

While catheter angiography has been the primary radiographic modality for diagnosing the extent of cerebrovascular trauma,7 CT angiography is an attractive screening imaging modality owing to the ease and rapidity of obtaining these images in the trauma setting. However, its sensitivity due to scatter artifact from the metallic foreign bodies is unclear.8 Nonetheless plain CT scan as well as CT angiograms are well-reported initial imaging modalities before surgical removal.7,9 Most of these injuries usually have relatively favorable neurological outcomes as long as the major cerebral vasculature and brainstem are not disrupted by the path of the penetrating nail.10

The primary and most commonly described vascular injury is the formation of a traumatic intracranial pseudoaneurysm, which necessitates both preoperative and follow-up cerebral angiography.8 Traumatic intracranial aneurysms are rare and they tend to manifest clinically within 3 weeks after the time of injury, associated with a 50% mortality rate.11 Because of the delayed visualization of traumatic pseudoaneurysms and the high risk of their formation in the setting of a nail gun injury, routine angiography should be performed in all patients between one to 2 weeks post injury.11

Infectious complications of penetrating head trauma are high, and include local wound infection, the formation of cerebral abscess, ventriculitis, and meningitis. However, the use of broad spectrum antibiotic prophylaxis is only recommended in penetrating neurotrauma although without established guidelines.12 In our patient, after discussion with our infectious disease colleagues, the patient received broad spectrum antibiotics for 5 days. Surgical treatment should be performed within 12 hours of the injury to decrease the risk of infectious complications.13 However, the technique to use is still debatable. No statistically significant advantage of one technique over the other has been described in reports of morbidity and mortality rates associated between a craniotomy or craniectomy.14 Whichever technique used, the mainstay of these injuries is the treatment goal of removal of the foreign object whether by removal under local anesthetics with the patient awake or emergent craniotomy under general anesthesia. Many single nail gun injuries were removed under local anesthetics with the patient awake.8 Blind removal is usually uneventful, however there have been complications arising such as subdural hematomas and even intraparenchymal hemorrhage. This has lead to the suggestion that all penetrating foreign bodies must be removed under direct vision.15 While most would proceed with a standard craniotomy around the foreign object, Spennato and colleagues16 describe the use of a double concentric craniotomy allowing for removal under direct visualization, without transmitting any undue forces to the underlying structures. This technique also facilitates hemostasis. In those situations when blind removal without formal craniotomy is judged appropriate, the availability of locking pliers (of the “Vise Grip ®” style) can be extremely helpful as their strong grip even with purchase limited to the edges of the nail head can permit extraction despite the usual firm implantation in the bone. The use of general anesthetic during removal is recommended for patients with more than 2 nails, high risks areas, or those in whom vascular injury is evident on preoperative imaging. Should there be evidence of injuries involving vascular structures, preoperative therapeutic embolisation should be considered. This allows angiographic visualization with endovascular control of the proximal injured vessel if needed, and immediate follow-up angiography post-removal. In addition, this is a feasible sole treatment technique where surgical management promises to be technically difficult or poorly tolerated by the patient, or when poor neurological condition does not warrant craniotomy.

Many patients presenting with intracranial injuries from nail gun misuse have an associated psychiatric disturbance, usually schizophrenia or major depressive disorder.17 As such, not only is it important to involve other surgical specialties for combined intracranial and extracranial injury, successful treatment requires the additional collaborative expertise of colleagues from psychiatry.

In conclusion, while most intracranial penetration from the use of a nail gun is single entry, here we present a case with 10 penetrating nail gun injuries. A careful clinical and radiologic examination is needed followed by extraction of the foreign body. Appropriate imaging includes CT scans with or without angiography and/or therapeutic embolisation. Most patients survive with good neurological outcome despite the dramatic appearance of the radiographic images.