Paediatric Penetrating Orbitocranial Injury with a Pencil - Report of Two Cases

Amal I Al-Hemidan(1), Selwa AF Al-Hazzaa(1), Imaduddin Kanaan(2)

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normal with good filling of the vascular tree and no fistulae were seen (Fig. 3). The case was managed surgically under general anaesthesia. The foreign body was approached by enlarging the entry wound in the upper eyelid. The main stem of the pencil was grasped with a clamp and pulled out slowly along the route of entry (Fig. 4). The surgical team remained on standby for emergency craniotomy in case of haemorrhage. Fortunately, the post-operative course was smooth.

Figure 4 — Case 1: The foreign body was approached by enlarging the entry wound and was pulled out following the same tract of entry.         Figure 5 — Case 2: Anteroposterior view showing the pencil extending from the left orbit to the anterior parietal area.         Figure 6 — Case 2: The pencil in its entirety.

The globe was found to be intact and fundus was normal on examination. The lid was sutured and an immediate post-operative CT scan was performed which showed a marked reduction in proptosis and no evidence of haematoma or vascular leak along the track of the removed pencil. Additional extracranial broken pencil wood and graphite could be identified in the superior fornix and were successfully removed. Tissue culture from the foreign body was negative. The wound was irrigated thoroughly with bacitracin. The patient was maintained on prophylactic antibiotic treatment with gentamicin and nafcillin for two weeks.Her tetanus immunisation was up to date. She recovered well with no post-operative infection. Follow-up ophthalmological examination one year later revealed a normal eye with visual acuity of 20/20 in both eyes and no neurolgoical deficit. Case 2: A 3-year-old female fell while carrying a pencil causing the pencil to enter the left orbit. The pencil shaft was removed in part by her father. Three days later, after a course of oral antibiotics at a local hospital, she was referred to King Faisal Specialist Hospital and Research Centre with a suspected intraorbital foreign body. On physical examination no neurological deficits could be identified. Ophthalmic evaluation was difficult due to severe chemosis and swelling of the lids. The skull x-rays showed a linear object with surrounding diminished density extending from the medial side of the left orbit to the left fronto-parietal area (Fig. 5). A bone fragment at the superior margin of the orbit was seen and was consistent with fracture of the roof of the orbit. CT scan showed air density extending from the medial side of the left orbit to the left parietal area. There was no evidence of haematoma or mass effect. At surgery the left eye was opened with difficulty. A conjunctival wound in the superior nasal fornix was seen. In the depth of the wound, the remainder of the pencil end was seen. The pencil was engaged with a clamp and removed slowly (Fig. 6). While preparation for craniotomy was on standby, the wound was irrigated. The globe was intact and the intraocular pressure was normal; culture of the wound was negative. Immediate repeat CT scan under general anaesthesia showed minimal intraorbital haematoma around the track of the pencil. No intracranial haematoma was identified. Repair of the conjunctiva and Tenon’s capsule was performed. Subconjunctival injections of gentamicin 20 mg and decadron 2 mg were given. Post-operatively, the patient received a prophylactic course of gentamicin, kefzol and decadron intravenously. There was no post-operative infection. Follow-up examination two years later showed no neurological complications and a final visual acuity of 20/20 in both eyes.

DISCUSSION

Orbitocranial penetration by a wooden object is relatively uncommon. It can cause considerable morbidity and mortality by direct damage to vital cerebral structures, or by circulatory compromise. In the above reported cases, no serious cerebral or ocular injuries were evident in the immediate or late post-trauma examinations. Post-traumatic amaurosis was not seen in either case although it has been reported.(11) Amaurosis can occur secondary to direct optic nerve damage, direct globe laceration or retinal ischaemia. Complications from a retained wooden foreign body are mainly related to infection. Mutlukan, et al. reported an infection rate of 64% despite antibiotic prophylaxis.(14) Brain abscess was found in 48% of these cases. Infection related complications following this type of injury can be due to the porous structure and the organic consistency of wood, which provides a natural reservoir and a good culture medium for microbial agents.(11)

Extensive intracranial damage may result even though the initial penetration is minimal. The superior orbital fissure and optic canal provide direct intracranial access, even when there is no fracture. Children are particularly prone to trans-orbitocranial injury because the orbital bone offers little resistance. The spectrum of intracranial complications as a result of penetrating orbito-cranial injury includes immediate structural injury, which is potentially fatal or can lead to permanent neurological deficit.(8) Vascular complications may include thrombosis, occlusion, pseudoaneurysm, rupture and carotid cavernous sinus fistula. Infective complications are more common in transorbital injury compared with other types of cranial injury due to the proximity of the orbit to the paranasal sinuses. Ocular complications include optic nerve damage with resultant severe loss of vision, extra-ocular muscle paralysis secondary to direct muscle trauma or nerve damage, proptosis and macular oedema.(6,9,11) A thorough ophthalmological examination is necessary even in the presence of an apparently trivial orbital wound and should be complemented by a baseline neurological evaluation. CT scans are essential for the evaluation of the extent of cerebral contusion, pneumocephaly, intraventricular or intracerebral haemorrhage, and cerebral angiography for any vascular lesion in these patients. In this regard, MRI and MRA would have been the preferred methods, had these been available at the time, to guide the physician in planning the appropriate line of treatment.

Wood is virtually undetectable on routine x-ray film since its radiodensity is very similar to that of the soft tissue.(1,12) However, the graphite component of a pencil might have been seen on plain x-ray in our two cases. The detection of an intracranial wooden object by CT scan is also difficult. Wood absorbs water and attains almost the same density as that of the brain tissue. It will be seen as a dark area around the graphite core and it may not be easy to differentiate it from an intracranial air bubble.(7,15) As the plane of the orbital roof and floor are nearly parallel to the scanning beam, only a small portion of these structures is visible on axial cuts. Coronal views are therefore recommended.

An intensive course of antibiotics must be started immediately after a perforating transorbital injury, even in the absence of any systemic or neurological signs of infection. Antibiotics alone may not suffice and a thorough surgical exploration must be carried out for any remaining wooden foreign body so that it can be removed without delay.(3) When intracranial extension is confirmed, it is essential to plan a surgical approach that takes into consideration the potential for emergency neurosurgical intervention.(5) A team approach, with close co-operation between ophthalmologists and neurosurgeons, is important to ensure optimal visual outcome and minimise the risk of devastating neurological complications.

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