Extended Retrolabyrinthine/Retrosigmoid Approach to a Transmastoid, Intracranial Speargun Injury

The temporal bone houses multiple critical structures inclusive of neural, vascular as well as the vestibulocochlear apparatus. Temporal bone injuries are often associated with the multitrauma patient. Such injuries may be overlooked because of a concomitant life-threatening emergency situation. They are thus associated with high morbidity states both due to the complexity and compactness of the at risk structures and the delays in forming an early diagnosis. This is an even greater risk when associated with penetrating high velocity injuries.

We highlight a case of speargun injury that penetrated the temporal bone into the posterior cranial fossa.

A 25-year-old patient was reportedly shot with a speargun. He presented to the emergency room in no cardiopulmonary distress or neuropathy. Computerized tomography (CT) and plain X-rays were done. They suggested a transmastoid route with extension into the posterior cranial fossa but radiological artifacts compromised film quality.

Intraoperatively the spear was severed to an inch from the surface of the skin. An initial cortical mastoidectomy was done. The spear was found embedded in the sigmoid sinus (SS). A retrolabyrinthine and retrosigmoid extension was done skeletonizing the SS and exposing dura on either side from sinodural angle to jugular bulb. A retrosigmoid dural window was made to view the tip of the spear which was noted to pierce the cerebellum's surface. Proximal and distal control of the SS was achieved with surgicel packing beneath the superior and inferior bony shelf of the SS bony canal as well as with vascular ties. The spear was then removed. No active bleeding from the cerebellar surface or SS defect was noted.

• Cerebrospinal fluid (CSF) continence was maintained with the following:Primary closure of retrosigmoid dura, reinforced with temporalis fascia (TF)

• Plugging of sigmoid sinus defect with TF

• Sealing of aditus ad antrum and facial recess air cells with TF and bone wax

• Packing the mastoid with harvested abdominal fat

• Careful overlapping fascial and skin closure

• Lumbar puncture drain

There were no postoperative neurological deficits.

Discussion: Speargun injuries are usually associated with high levels of morbidity and mortality as they are penetrating high-velocity injuries. Preoperative evaluation in injuries such as these where the metallic weapon remains in-situ is often suboptimal because of the unavailability of MRI and suboptimal CT scan due to artifacts. Despite this, a CT scan can still provide invaluable information.

There are limited cases in the literature with speargun injuries and this is the first case to be managed in this manner. This case report strongly reinforces the proposal to only attempt removal under direct vision as this reduces morbidity and mortality. Adequate exposure of at-risk structures inclusive of the entire sigmoid sinus as well the track of the spear is ideal before removal. It also enhances the opportunity to ensure a water tight closure. The type of exposure is dependent on the trajectory of the weapon. Blind removal often results in disastrous consequences especially and risks worsening the morbidity/mortality, for example, hemorrhaging because of vascular damage as in this case.