A two-year-old boy presented with a right upper eyelid laceration, two hours after a fall from a table. The child was playing with color pencils with his brother during which he sustained the injury.

Ophthalmic examination revealed a laceration measuring 1.5 cm x 0.5 cm involving the central part of the right eyelid with minimal edema [Fig. 1A]. The rest of the ocular examination was normal, except that on testing the extraocular movements of the right eye, the child was uncooperative for elevation due to pain. Neurological examination revealed no abnormality. The patient was taken under general anesthesia for a detailed examination and lid laceration repair. However, on the operation table minimal clear fluid coming out through the wound margins was observed. Analysis of fluid revealed a beta-tracer protein value of 33.5 mg/l, suggestive of cerebrospinal fluid (CSF). The patient underwent an urgent computed tomography (CT) scan of the orbit and brain which revealed a linear hyperdense shadow with surrounding hypodensity measuring 4.2 cm x 0.8 cm, suggestive of a broken pencil [Fig. 1B–D]. Three-dimensional (3D) reconstruction documented that the pencil had penetrated the right frontal lobe through the orbital roof ending just anterior to the anterior horn of the lateral ventricle [Fig. 2A–D]. A multidisciplinary approach consisting of an orbital surgeon and a neurosurgeon was used to manage this patient. After neurosurgical clearance, the orbital surgeon explored the upper eyelid wound and the pencil was removed from the foreign body tract followed by laceration repair [Fig. 3A]. A craniotomy was then performed by the neurosurgeon which revealed laceration at the base of the right frontal lobe. The defect in the dura was closed with a pericranial graft from the right frontal bone. The patient was started on intravenous third-generation cephalosporin (Ceftriaxone Rocephine^®) for seven days and had an uneventful recovery.

Postoperatively there was minimal ptosis of the right upper lid which resolved in a month [Fig. 3B]. Three months following surgery patient underwent a complete neurological examination which was normal. Magnetic resonance imaging of brain showed a cortical and subcortical fibrotic lesion measuring 1 mm at the base of the right frontal lobe corresponding to the laceration. At the last follow-up, two years after surgery the patient had no ocular or neurological abnormality.

Orbito-cranial injuries by foreign bodies are occult if the presenting injury is deemed minimal and the ophthalmological and neurological evaluation are otherwise within normal limits.[¹] The roof of the orbit provides one of the easiest entry routes for a foreign body into the brain as it is relatively thin in this location.

Trivial-appearing eyelid lacerations may camouflage occult deep penetrations and are frequently sutured without further investigation.[⁶–⁸] CSF leakage is associated with a 20% risk of life-threatening meningitis hence its detection and management is essential to prevent possible life-threatening infections of the central nervous system.[⁹] In a review of the literature on occult orbito-cranial injuries complications like frontal lobe abscess,[²] meningitis,[²] encephalomeningocele[³] and retained foreign body[⁴] have been reported.

Beta-TP is a highly specific marker for CSF, produced mainly in the epithelial cells of the choroid plexus. It has a sensitivity of 93–100% and a specificity of 100% for detecting CSF leaks.[¹⁰] The technique involves centrifuging the fluid sample at 2000 g for 10 min. The BN II nephelometer and the N Latex βTP^® test (Dade Behring, Marburg Germany) are used. Samples (5 μl) are diluted to a total volume of 500 μl with diluens buffer (Dade Behring, Marburg, Germany) and measured on the nephelometer. The concentration in normal CSF is 5.4-23.8 mg/l and for serum it is 0.2-0.7 mg/l.[¹⁰] The detection of beta-TP from the fluid around the wound margins in our patient was suggestive of CSF leak from an occult penetrating orbito-cranial injury.

The reason we took the patient under general anesthesia before a definitive radiological procedure is that firstly it gave us a chance to examine the wound thoroughly as the initial ophthalmic examination did not reveal any suspicion of an intraorbital foreign body and secondly a positive beta-TP intra-operatively gave us a very strong indication for ordering a definitive radiological investigation following which a three-dimensional CT scan and further management were performed in the same sitting.

A coordinated team approach between an ophthalmologist and neurosurgeon is essential for managing these injuries.[⁵] We removed the foreign body through the laceration, as this approach gives a faster, less invasive way to extract the foreign body than a craniotomy, and the recovery time is reduced.

The detection of beta-TP is currently been used in the field of neurosurgery and otolaryngology to diagnose CSF leaks following head injuries, skull base or paranasal sinus surgeries.[⁹] An online PubMed search was carried out which revealed that the application of beta-TP has never been reported in ophthalmic literature. The detection of beta-TP is simple, rapid (within 15 min) and relatively inexpensive, hence we recommend it to be used as a screening procedure before definitive radiological procedures are planned in cases where CSF leaks are suspected.