Wearable Mixed-Reality Holographic Navigation Guiding the Management of Penetrating Intracranial Injury Caused by a Nail

Abstract

Penetrating brain injury caused by a nail is an extremely rare neurosurgical emergency that poses a challenge for neurosurgeons. Nail entering the brain from the orbit and lodging within the cranial cavity is even more unusual. A 53-year-old male was found unconscious at a construction site, and brain CT revealed not only the presence of a nail beneath the inner table of the parietal bone, but also traumatic intracerebral hematoma. Consequently, accurate localization of the nail and hematoma was mandatory for surgical plan. During surgical planning, computational model reconstruction and trajectory calculation were completed using preoperative CT in 3D Slicer. Under the guidance of a head-mounted mixed-reality holographic computer, the neurosurgeon was able to visualize and interact with the hologram of the surgical plan, and intraoperative findings demonstrated that our low-cost portable wearable mixed-reality holographic navigation assisted precise localization of the nail and intracerebral hematoma, assuring less injury to the already compromised brain. After the surgery, the patient could obey commands, and postoperative imaging ruled out the possibility of brain abscess during follow-up. To the best of our knowledge, this is the first report on using a low-cost wearable mixed-reality holographic navigation to guide the management of penetrating intracranial injury caused by a nail.

Background

Penetrating brain injury caused by a nail gun is an extremely rare neurosurgical emergency that poses a challenge for neurosurgeons because of its rarity and complexity [1, 2]. Injuries caused by penetrating foreign bodies can include intracranial hemorrhage, cerebral contusion, infection, seizures, and cerebrospinal fluid fistula [2]. Most of the cases reported in the literature were nails penetrating from the convexity of the skull and leaving obvious part of their bodies outside the scalp, which can be easily located during operation. A nail that enters the brain from the orbit and completely lodges within the cranial cavity is very unusual, and accurate localization is the key point for the surgical removal of the nail. Our low-cost portable wearable mixed-reality holographic navigation assists the nail and intracerebral hematoma localization, ensuring less injury to the already compromised brain. To the best of our knowledge, this is the first report of using wearable mixed-reality holographic navigation to guide the management of penetrating intracranial injury caused by a nail.

Methods

Patient Information

A 53-year-old male patient was found unconscious with bleeding from his left orbit and a nail-gun lying by his side at a construction site. A seizure during the transfer to our emergency department was described by his family. The Glasgow coma scale was 4, and physical examination revealed a complete damage of the left eyeball. In addition, clear and non-mucoid running fluid from nose was presented with mixed bleeding. No wound of exit was observed on the scalp. Brain CT revealed not only the presence of a metallic density object in the left parietal lobe with its long axis (about 3.5 cm) tangent to the parietal bone and approximately 2 cm from midline (Fig. 1a), but also traumatic intracerebral hematoma which had burst into the ventricle (Fig. 1b). CT also showed comminuted fracture of nasal and ethmoid bones on the left (Fig. 1c) as well as tentorial herniation of brain.

Fig. 1.

a Brain CT indicated the nail in the left parietal lobe with its long axis tangent to the parietal bone. b Nail induced traumatic intracerebral hematoma burst into the ventricle. c CT also showed comminuted fracture of nasal and ethmoid bones

Data Processing and Holographic Visualization

We obtained the consent of the family members of the patient. CT data was acquired using a 128-slice CT scanner (uCT760, United Imaging Healthcare Corp., Shanghai, China) before and within 24 h after surgery. Imaging parameters were as follows: isotropic voxel size 0.625 × 0.625 × 0.625 mm, matrix size 512 × 512. Preoperative DICOM data were imported into 3D Slicer software [3] (version 4.10, nightly build, Surgical Planning Laboratory, Harvard Medical School). The surgical planning procedures were conducted as follows. Virtual segmentation and modeling were performed for the nail, hematoma, skull, and the patient’s head (Fig. 2a, b). All of the reconstructed models were uploaded into our in-house holographic surgical planning viewer for visualization of the holograms after colorization and “transparentization” using its personal computer client. This process allowed wireless access of the data by a head-mounted device, the Microsoft HoloLens (developer’s edition, Microsoft Inc.). In addition, our in-house software, holographic surgical planning (HSP) viewer, advanced the registration accuracy of such wearable mixed-reality holographic computer [4]. The whole data processing time only took 35 min that caused no delay of the surgery, since such data processing was being performed during surgical preparation such as patient transportation, anesthesia, and central venous catheterization.

Fig. 2.

a, b Lateral and oblique views of the surgical plan. Blue: the penetrating trajectory which is 16 cm long; yellow: the skull; purple: the nail under the inner table of the left parietal bone; red: hematoma along the penetrating trajectory and burst into the ventricle. c Wearing the headset, the neurosurgeon visualized holograms of the surgical plan. d The head-mounted device created a feeling of actual physical presence of the computational objects including the nail, hematoma, skull, and the patient’s head. The “buttons” on the left represented different module functions that could be applied on the holograms in our in-house software. From top to the bottom, the labels meant “rotate”, “zoom”, “display”, “see-through”, “register”, and “lock”, respectively. e, f The neurosurgeon was able to inspect the holograms closer or walk around them from varying viewpoints. White arrow: nail; black arrow: hematoma

Results

Wearing the HoloLens enabled the neurosurgeon to visualize holograms of the surgical plan through high-definition lenses with small computer screens positioned in front of the eyes (Fig. 2c). In addition, gesture control allowed the interaction with the holograms. The head-mounted device succeeded in creating a feeling of actual physical presence of the computational objects including the nail, hematoma, skull, and the patient’s head (Fig. 2d). The neurosurgeon was able to inspect them closer (Fig. 2e) or walk around them from varying viewpoints (Fig. 2f).

After general anesthesia of the patient, the neurosurgeon, wearing the head-mounted device (Fig. 3a), performed the registration between the patient’s head and its computational counterpart (Fig. 3b), and the positions of the nose and ear verified the precision of registration. Thusly, the spatial localization of the nail and hematoma was intuitively determined, and skin incision markers were drawn (Fig. 3c).

Fig. 3.

a The neurosurgeon, wearing the head-mounted device, performed the registration between the patient’s head and its computational counterpart. b First-person perspective of the neurosurgeon while performing registration. The non-English label in Chinese meant “move”, indicating the neurosurgeon was using such module to move the holograms along the X-axis. c After registration, the spatial positions of the nail and hematoma were determined. Purple: the nail; red: hematoma

During the surgery, wearing the head-mounted device and using gesture control (Fig. 4a), the neurosurgeon interacted with the holograms and customized the dura opening under the guidance of the nail hologram (Fig. 4b), consequently revealed the tail of the nail (Fig. 4c) which precisely aligned with its holographic counterpart. The intraoperative screenshot verified the accuracy of our holographic navigation (Fig. 4d) and the nail was carefully withdrawn (Fig. 4e, f). Guided by the same method, hematoma evacuation was also accomplished by penetrating the closest cortex to the hemorrhage.

Fig. 4.

a Wearing the headset and using gesture control, the neurosurgeon interacted with the holograms. b The dura opening was customized under the guidance of the nail hologram (black arrow). c The revealed tail of the nail (white arrow). d, e The intraoperative screenshot verified the accuracy of our holographic navigation and the nail was carefully withdrawn. f The nail was 3.5 cm long

The day after the surgery, the patient could obey commands, and the muscle strength on the right was II, and V on the left. Postoperative brain CT scan demonstrated the removal of the nail and intracerebral hematoma. Osmotherapy was applied based on a continuous intracranial pressure monitor, and tetanus prophylaxis and broad-spectrum antibiotic therapy was started as soon as possible. In addition, anticonvulsant was also applied. Both contrast-enhanced and diffusion-weighted MRI ruled out the possibility of brain abscess during a 6-month follow-up.

Discussion

Penetrating brain injury caused by a nail gun is an extremely rare neurosurgical emergency. Due to its rarity and complexity of nail gun-induced brain injury, it poses a challenge for the neurosurgeons [5, 6]. Several cases have been reported [2, 7]; however, all nails in these cases are penetrating from the convexity of the skull and usually leave part of their bodies outside the scalp, which can be easily located. With regards to our case, the nail enters the cranial cavity from the orbit, breaking through the ethmoid bone and brain, and reaches the inner table of the left parietal bone, which is very hard to be quickly pinpointed. Consequently, accurate nail localization is mandatory since no conspicuous clue of the nail’s position can be observed by the naked eye. To address the above-mentioned problems, a fast and precise patient-tailored navigational approach would be very beneficial. However, since currently available navigational devices are expensive and large enough to take up valuable space, image-guided methods are not routinely applied in every neurosurgical department especially for emergency cases. Our previous study demonstrates the use of a low-cost head-mounted mixed-reality holographic navigation to successfully perform hologram-assisted bedside external ventricular drain insertion. We also provide preliminary confirmation of the feasibility and accuracy of this hologram-guided technique [4]. Using such system, it offers a quick and portable approach to create an impression of the actual physical presence of the nail and hematoma within the patient’s head, but also allows the neurosurgeon to interact with their holograms by gesture and voice, which satisfies the aseptic demands for surgical operation. Real-time taken intraoperative pictures, though difficult to convey the created feeling of actual physical presence of the computational object, verify the feasibility and accuracy of such mixed-reality holographic guidance. In addition, intracerebral hematoma localization is also prompted by the holographic navigation. Under its guidance, a minimized open of the cortex can be ensured for the hematoma evacuation. Such accurate localization method allows less injury to the already compromised brain.

Conclusion

To the best of our knowledge, this is the first report on the feasibility and accuracy of using a low-cost wearable mixed-reality holographic navigation to guide the management of penetrating intracranial injury caused by a nail.

Funding

This work was supported by the National Natural Science Foundation of China (81701796), Capital Health Research and Development of Special (2020-2Z-2019), the China Scholarship Council (CSC No. 201406200059), and Chongqing Science and Health Joint Medical Research Project (2020MSXM078).

Declarations

Ethical Approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.