What is the most likely cause of intense pain radiating to the inner ear and loss of balance after a fall with loss of consciousness (LOC) and trauma to the left zygomatic arch?

Most Likely Diagnosis: Temporal Bone Fracture with Inner Ear Injury

The most likely cause is a temporal bone fracture with labyrinthine concussion (inner ear injury), which explains the triad of intense pain radiating to the inner ear, loss of balance, and the mechanism of blunt trauma to the zygomatic arch with loss of consciousness. 1, 2

Critical Initial Assessment

This patient requires immediate CT imaging of the maxillofacial region and temporal bones given the loss of consciousness and mechanism of injury. 1, 3

Key points about the presentation:

• Loss of consciousness with head trauma mandates neuroimaging - patients with isolated transient LOC have an 18.9% rate of requiring emergency operative intervention, including 4% requiring craniotomy 4
• CT maxillofacial is the preferred initial imaging modality for suspected midface injuries, providing high-resolution delineation of osseous and soft-tissue structures 3
• All patients with transient LOC after trauma should undergo CT scanning to prevent deterioration in the emergency department 5

Differential Diagnosis and Clinical Reasoning

Primary Concern: Temporal Bone Fracture with Labyrinthine Injury

The constellation of symptoms strongly suggests temporal bone involvement:

• Intense pain radiating to the inner ear indicates potential temporal bone fracture extending toward the petrous portion 6
• Loss of balance suggests vestibular apparatus damage (labyrinthine concussion) 6
• Mechanism: Blunt force to the zygomatic arch can transmit forces to the temporal bone, particularly given the anatomical proximity 3

Important caveat: Labyrinthine concussion can occur without visible fracture on imaging - isolated cochlear or vestibular damage may present with normal CT findings 6

Secondary Considerations

Zygomatic arch fracture complications to evaluate:

• Zygoma fractures are the second most common isolated facial fracture 3
• Associated orbital floor fractures may cause diplopia, enophthalmos, or oculocardiac reflex 2
• Muscle entrapment with oculocardiac reflex (bradycardia) requires immediate surgical repair 2

Intracranial injury must be ruled out:

• Patients with GCS 14 or less, or GCS 15 with LOC, have 3-13% risk of acute intracranial lesion 1
• Variables predicting intracranial injury include: dangerous mechanism, neurologic deficit, vomiting, severe headache, signs of basilar skull fracture 1

Immediate Management Algorithm

Step 1: Stabilization and Vital Signs

• Monitor for bradycardia or heart block (oculocardiac reflex from potential orbital muscle entrapment) 2
• This is a potentially life-threatening condition requiring urgent intervention 2

Step 2: Neurologic Assessment

• Complete GCS scoring 1
• Detailed sensorimotor examination including extraocular movements, versions, ductions, saccades 2
• Assess for focal neurologic deficits 1

Step 3: Imaging

• CT maxillofacial with attention to temporal bones 3
• Look for:
  • Temporal bone fractures (longitudinal or transverse)
  • Zygomatic arch fractures
  • Orbital floor fractures
  • Intracranial hemorrhage
  • Pneumocephalus or CSF leak

Step 4: Specialized Consultation

• Neurosurgery if intracranial pathology identified 1
• Otolaryngology for temporal bone fracture or persistent vestibular symptoms 6
• Ophthalmology if orbital involvement with diplopia or enophthalmos 2
• Oral-maxillofacial surgery for zygomatic arch fracture management 2

Common Pitfalls to Avoid

Do not assume normal imaging excludes inner ear injury: Labyrinthine concussion can occur without visible fracture, presenting with sensorineural hearing loss and vestibular symptoms 6

Do not discharge without proper instructions: Patients with mild TBI and negative CT still require specific return precautions including repeated vomiting, worsening headache, confusion, focal deficits, increased sleepiness, or seizures 1

Do not miss contralateral injuries: Though rare, inner ear injury can occur contralateral to the side of impact 6

Do not delay surgical intervention if indicated: Muscle entrapment with oculocardiac reflex, globe subluxation, or "white-eyed blow-out fracture" require immediate surgical repair 2

Expected Clinical Course

• Up to 28% of mild TBI patients develop postconcussive symptoms lasting beyond 6 months 1
• Symptoms may include chronic headaches, dizziness, balance problems, and vision problems 1
• Patients should receive written discharge instructions at sixth-grade reading level 1
• Follow-up with TBI specialist if symptoms persist beyond 3 weeks 1