Ophthalmology · Orbital Trauma
The facts most likely to be tested
Blowout fractures most commonly involve the inferior orbital wall (maxillary sinus floor) due to the thinness of the bone.
Patients typically present with diplopia caused by entrapment of the inferior rectus muscle.
Physical examination reveals infraorbital nerve paresthesia (numbness of the cheek, upper lip, and gingiva) due to nerve compression.
Enophthalmos is a classic late finding resulting from increased orbital volume and herniation of orbital contents.
Non-contrast CT scan of the orbits is the gold standard diagnostic imaging modality to confirm the fracture.
Initial management includes nasal decongestants, avoiding the Valsalva maneuver, and prescribing prophylactic antibiotics to cover sinus pathogens.
Surgical repair is indicated for patients with persistent diplopia, significant enophthalmos, or large fractures involving more than 50% of the orbital floor.
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A 24-year-old male presents to the emergency department after being struck in the right eye with a baseball. He complains of double vision when looking upward. Physical examination reveals restricted upward gaze in the right eye and numbness over the right cheek and upper lip. A non-contrast CT of the orbits demonstrates a fracture of the orbital floor with herniation of orbital fat into the maxillary sinus.
Which muscle is most likely entrapped in this patient's injury?
Inferior rectus muscle
The patient's presentation of diplopia on upward gaze and infraorbital nerve paresthesia is classic for an orbital floor blowout fracture, which frequently causes entrapment of the inferior rectus muscle.
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Etiology / Epidemiology
Caused by blunt force trauma to the orbit, typically from a ball or fist. Most common in young males.
Clinical Manifestations
Presents with diplopia on upward gaze and infraorbital nerve anesthesia. Look for enophthalmos.
Diagnosis
CT scan of the orbits (non-contrast) is the gold standard. Look for the teardrop sign.
Treatment
Initial management includes nasal decongestants and oral antibiotics. Avoid Valsalva maneuvers.
Prognosis
Surgical repair indicated for persistent diplopia or large fractures (>50% of floor).
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Epidemiology & Etiology
Commonly occurs in young adults following high-velocity blunt trauma to the globe. The orbital floor is the most frequent site of fracture due to its thin structure. Often associated with sports injuries or interpersonal violence.
Pertinent Anatomy
The orbital floor is formed by the maxillary bone, which is the weakest point. The infraorbital nerve runs through this floor, explaining sensory deficits. The inferior rectus muscle can become entrapped within the fracture site.
Pathophysiology
Sudden increase in intraorbital pressure causes a 'blowout' of the thin orbital floor into the maxillary sinus. This leads to the entrapment of the inferior rectus muscle or orbital fat. Mechanical restriction of the muscle prevents normal ocular motility, specifically upward gaze.
Clinical Manifestations
Patients present with diplopia (double vision) and infraorbital nerve anesthesia (numbness of the cheek/upper lip). Physical exam reveals enophthalmos (sunken eye) and restricted extraocular movements. Red flags include retrobulbar hematoma causing vision loss, which is a surgical emergency.
Diagnosis
The CT scan of the orbits (coronal views) is the gold standard for diagnosis. Radiographic findings include the teardrop sign, representing herniated orbital fat into the maxillary sinus. Always perform a complete ophthalmologic exam to rule out globe rupture.
Treatment
Initial treatment involves nasal decongestants to prevent sinus pressure and prophylactic antibiotics (e.g., amoxicillin-clavulanate) to cover sinus flora. Contraindications include blowing the nose, which can force air into the orbit. Surgical repair is indicated for persistent diplopia or large floor defects.
Prognosis
Most patients recover well with conservative management if the fracture is small. Key complications include permanent diplopia, chronic enophthalmos, and infraorbital nerve paresthesia. Follow-up with an ophthalmologist is required within 1 week.
Differential Diagnosis
Orbital floor blowout: restricted upward gaze
Orbital wall fracture: medial wall involvement
Globe rupture: positive Seidel test
Retrobulbar hematoma: emergency vision loss
Orbital cellulitis: fever and elevated WBC