A case of open skull fracture, subdural hematoma, and brain contusion complicated by traumatic brain injury-associated coagulopathy caused by a lawn trimmer; A case report

Abstract

Penetrating head injury is less common than blunt head injury in Japan but causes devastating complications and requires prompt surgical intervention. However, not all penetrating head injuries are apparent on arrival.

We herein present a case of a 74-year-old male who lost his balance on a steep hillside and fell on an active lawn trimmer with rotating circular blades, which hit his face. On arrival, the patient was alert and conscious, but was unable to recall the accident. His vital signs were stable and motor functions were normal. The patient had a large laceration ranging from the right lower eyelid to the back of the right auricle. The wound appeared to be superficial with no apparent bone fragments or exposure of the cerebrum. However, trauma CT pan-scan revealed a right temporal bone fracture with multiple skull fragments scattered inside the cranium, and a right temporal lobe contusion. The patient became agitated in the CT suite, followed by a decreased level of consciousness. By the time the patient was rushed back to the emergency room, he was unconscious with minimal respiratory effort, decreased blood pressure, and anisocoria. Blood tests showed evidence of traumatic brain injury-associated coagulopathy. The present case demonstrates how penetrating head injury caused by lawn trimmers may appear subtle in physical examination. The present case also serves as a stark reminder that patients with a high-risk injury or amnesia should undergo trauma CT pan-scan as soon as possible and under-triage of these patients may have devastating consequences.

Highlights

• •This case demonstrates that lawn trimmers can cause penetrating head trauma and that the wound may appear subtle in physical examination.
• •Penetrating head trauma caused by lawn trimmer can be complicated by traumatic brain injury associated coagulopathy.
• •This case is a reminder that patients with a high risk injury or amnesia should undergo trauma CT pan-scan.

Introduction

Traumatic brain injuries are common worldwide, affecting approximately 69 million individuals annually, and their severity ranges from mild to severe [1]. In Japan, the majority of brain injuries in the elderly are caused by blunt injuries, while penetrating brain injuries are rare [2]. Penetrating head injuries may have dire consequences for patients, such as traumatic cerebrovascular injuries, intracranial infections, and cerebral fluid leaks [3]. Prompt surgical intervention is essential for a better outcome. However, not all penetrating brain injuries are obvious during the primary examination, which may result in a delayed diagnosis and, thus, increased mortality and morbidity.

Case

A 74-year-old male was transported to our emergency department 1 h after receiving a blow to the right side of his face with a grass trimmer. The exact injury mechanism was initially unknown because the patient was unable to recall the accident and the person who witnessed the accident was too distressed to describe it. On arrival, the patient was alert, conscious, and co-operative with normal motor functions. His vital signs were within normal limits with no obvious sign of shock. His pupils were equal and reactive. A physical examination showed a large contusion that ranged from below the lower eyelid to the temporal side of the head (Fig. 1). Active bleeding was present, which made wound exploration difficult; however, the contusion appeared to be superficial and there were no apparent signs of open fracture or cerebral prolapse. The patient was transported to the CT suite and trauma CT pan-scan revealed a right temporal bone fracture with multiple skull fragments scattered inside the cranium, a right temporal lobe contusion, bilateral sub-arachnoid hemorrhage, and a right subdural hematoma (Fig. 2a, b, c, d). These findings indicated that the blade of the lawn trimmer actually penetrated the skull. While in the CT suite, the patient became agitated and confused, and this was followed by a decreased level of consciousness. The patient was rushed back to the emergency room for stabilization. By the time the patient had arrived at the emergency room, he was unresponsive to painful stimuli with minimal respiratory effort, decreased blood pressure, and anisocoria. The patient was intubated and vasopressors were initiated along with blood transfusion and the administration of tranexamic acids. The patient underwent urgent craniotomy after stabilization.

Fig. 1.

Laceration of the right face. Legends: A physical examination revealed a large laceration on the right temple ranging from the right lower eyelid to the back of the right auricle.

Fig. 2.

CT images of the head. Legends 2a: Transverse image of head CT revealed a right temporal bone fracture with multiple skull fragments scattered inside the cranium, a right temporal lobe contusion, bilateral sub-arachnoid hemorrhage, and a right subdural hematoma. Legends 2b: 3D reconstruction image of head CT revealing the point of penetration in the temporal bone.

Initial blood tests were as follows: white blood cell count 11,140/μl, red blood cell count 495 × 10⁴/μL, hemoglobin 16.6 g/dl, platelet count 17.6 × 10⁴/μL, PT(sec) 12.1 s, PT-INR 1.08, fibrinogen 261 mg/dl, FDP 76.4 μg/dl, D-dimer 35.7 μg/ml, and AT3 activation 69 %. Increased D-dimer and FDP levels, the decreased fibrinogen level, and AT3 activation indicated disseminated intravascular coagulation (DIC). The DIC score according to the Japanese Association for Acute Medicine (JAAM) diagnostic criteria was 6. Follow-up coagulation blood tests 1 h after arrival were as follows: platelet count 14.2 × 10⁴/μL, PT(sec) 13.4 s, PT-INR 1.2, fibrinogen 188 mg/dl, FDP 117.5 μg/ml, D-dimer 64.7 μg/ml, and AT3 activation 62 %, indicating deteriorating acute trauma coagulopathy.

Intraoperative findings revealed a dural laceration, brain prolapse, a subdural hematoma, massive contusion of the right temporal lobe, and an intracranial hematoma (Fig. 3a and b). The massive cerebral contusion required internal decompression.

Fig. 3.

Intraoperative image. Legends 3a: Intraoperative findings revealed a dural laceration, brain prolapse, a subdural hematoma, a massive contusion of the right temporal lobe, and an intracranial hematoma. Legends 3b: The black arrow indicates the right temporal bone. The trajectory of the lawn trimmer lies next to the temporal bone fragment. The green arrows indicates the severed right temporalis muscle. The yellow arrow indicates the point of entry of the lawn trimmer. The orange arrow indicates the cephalic direction of the patient. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

It was later revealed that the patient had lost his balance while on a steep cliff, fell on the lawn trimmer operated by his colleague, and the rotating circular blades of the trimer hit his head. The patient was discharged to a nursing facility on postoperative day 30 with right face palsy and cognitive dysfunction.

Discussion

The present case demonstrates that severe penetrating brain injury caused by a lawn trimmer may appear to be subtle in a physical examination with the patient having a normal level of consciousness.

The majority of penetrating brain injuries are caused by high velocity missiles, with bullets being the most common. Penetration of the brain by a low velocity object depends on its energy, shape, angle of approach, and the tissue it penetrates [4]. Land trimmers are lower powered than land mowers, and are only capable of causing minor fractures, lacerations, and sprains [5]. Between the year 2000 and 2009 an estimated 81,907 injuries were attributed to land trimmers in the United States. The most common area of injury was the eye which consisted 35.6 % of all injuries while the head and neck (eye excluded) consisted 6.9 % of all injuries. Fracture of the head and neck region was rare, consisting 0.3 % of all the head and neck injuries [5].

However, penetration through the temporal bone may be achieved with minimal force through the squamous part [6]. Our patient fell on a rotating land mower from the right side of his face and head CT revealed that the point of penetration was the temporal bone (Fig. 2a, b, c, d). Based on these findings, the lawn trimmer penetrated the brain despite its low power because it came into contact with the weak point of the temporal bone. The thin nature of the lawn trimmer blade caused minimal damage to the surrounding tissues, thereby giving the appearance of a superficial laceration.

Head trauma in the present case was complicated by traumatic brain injury associated coagulopathy. Patients with penetrating brain injury have a higher incidence of coagulopathy potentially due to more severe damage to cerebral tissue and disruption of the blood-brain barrier [7]. Traumatic brain injury-associated coagulopathy induces both hypercoagulable and hyperfibrinolytic states and manifests as disseminated intracranial hemorrhage, a delayed intracranial or intracerebral hematoma, and systemic bleeding [8]. Traumatic brain injury leads to a coagulopathic state partially because cerebral tissue is rich in potent platelet-activating and procoagulant sources [7].

A systematic review of the literature on hemostatic disruption following traumatic brain injury by Fletcher-Sandersjöö et al. [9] showed that traumatic brain injury was followed by temporary increases in PTT, APTT, and PT, which were the 3 most pronounced changes in the first hour of injury. Increases in PTT and PT indicate a dysfunction in the coagulation cascade. Increases in D-dimer levels have also been reported following traumatic brain injury, with a peak being observed in the first 6 h after injury. These increases show that traumatic brain injury is followed by hyperfibrinolysis, which also contributes to hemorrhage expansion [9]. On arrival to our department, the patient's PT(sec) was 12.1 s, FDP was 76.4 μg/dl, and D-dimer was 35.7 μg/ml. These results indicate that the patient was in a state of both hyperfibrinolysis and coagulation dysfunction within 1 h after the incident.

In the present case, a massive contusion to the right temporal lobe was found during surgery, which required internal decompression. We considered extensive damage to the cerebral tissues caused by the lawn trimmer induced traumatic brain injury-associated coagulopathy and exacerbated intracranial hemorrhage.

To the best of our knowledge, this is the first case report of open skull fracture and massive cerebral contusion complicated by traumatic brain injury-associated coagulopathy caused by a lawn trimmer.

The subtle nature of the laceration together with the patient's normal conscious level and unknown mechanism of injury due to amnesia led to under-triage and a delay in the diagnosis of this patient. This case is a stark reminder that patients with a high risk injury mechanism of head injury or amnesia need to undergo CT even if a physical examination reveals normal neurological and motor functions because these patients are at an increased risk of significant brain injury requiring neurological intervention [10].

Conclusion

A land trimmer caused an unexpected severe penetrating brain injury accompanied by acute trauma coagulopathy while appearing to be subtle in a physical examination. Patients with a high risk injury mechanism or amnesia need to undergo CT as soon as possible because they are at an increased risk of significant brain injury.

CRediT authorship contribution statement

Mitsutoshi Okuda: Writing – original draft, Investigation, Data curation, Conceptualization. Atsushi Morizane: Writing – review & editing. Sunao Asaba: Supervision. Saika Tsurui: Supervision. Ryutaro Tsuno: Supervision. Daichi Yamasaki: Writing – review & editing. Mariko Hatakenaka: Supervision. Tomoko Sugimura: Validation. Yuichi Saisaka: Writing – review & editing, Supervision.

Declaration of competing interest

We have read and understood the journal's “Guide for Authors”, and we believe that the manuscript is in compliance with all policies and does not violate any of these. All of the authors have read and agreed to the submitted version of the paper, and bear responsibility for it. All authors have also agreed to be include in the paper. This manuscript is original and has not been published or presented elsewhere in part or in entirety and is not under consideration by another journal. We agree that should the manuscript be accepted, the manuscript will not be published elsewhere in the same or similar form, in English or in any other language, without written consent of the copyright holder. We have received no funding and we have no conflict of interest. We declare that we have not used generative AI for the writing of this manuscript.