What happens if the injector touches a nerve during a platelet-derived growth factor (PDGF) injection under the eye?

Nerve Contact During Under-Eye PDGF Injection

Direct Answer

If the injector touches a nerve during under-eye PDGF injection, the patient will typically experience immediate sharp pain, and there is risk of temporary or permanent sensory disturbance, nerve palsy, or motor dysfunction depending on which nerve is contacted.

Understanding the Periorbital Nerve Anatomy

The under-eye region contains several critical nerves that can be contacted during injection:

• Infraorbital nerve (branch of maxillary division of trigeminal nerve) exits through the infraorbital foramen approximately 1 cm below the orbital rim and provides sensation to the lower eyelid, upper cheek, and lateral nose
• Branches of the facial nerve control the orbicularis oculi muscle and other periorbital muscles
• Direct needle trauma to these structures can cause immediate pain, paresthesias, or motor weakness

Immediate Consequences of Nerve Contact

Sharp, shooting pain is the most common immediate symptom when a needle contacts a nerve, which should prompt immediate cessation of injection and needle withdrawal.

Sensory Nerve Injury

• Temporary paresthesias (numbness, tingling, burning) in the distribution of the affected nerve
• Dysesthesias (abnormal, unpleasant sensations) that may persist for days to months
• Permanent sensory loss is rare but possible with direct nerve transection or severe trauma

Motor Nerve Injury

• Temporary weakness of periorbital muscles if facial nerve branches are injured
• Ptosis or eyelid malposition if nerves controlling eyelid function are affected
• Case reports document cranial nerve palsies following periocular injections, including sixth nerve palsy after intravitreal injection 1

Risk Mitigation Strategies

Proper injection technique is critical to avoid nerve injury:

• Use topical anesthetic before injection to reduce patient discomfort and movement 2
• Inject slowly and superficially in the tear trough region, staying in the subdermal or supraperiosteal plane
• Stop immediately if the patient reports sharp, shooting pain suggesting nerve contact
• Avoid injecting near the infraorbital foramen (typically 1 cm below the mid-pupillary line at the orbital rim)
• Use small gauge needles (30-gauge or smaller) to minimize trauma 2

Management of Nerve Injury

If nerve contact occurs during injection:

• Immediately withdraw the needle without injecting further material
• Document the event including patient symptoms and examination findings
• Assess sensory and motor function in the affected distribution
• Observe for resolution - most minor nerve injuries resolve spontaneously within weeks to months
• Consider neurology referral if symptoms persist beyond 4-6 weeks or worsen
• Avoid re-injection in the same location until complete resolution

Common Pitfalls

• Injecting too deeply increases risk of contacting deeper nerve structures
• Ignoring patient pain reports during injection - sharp pain is a warning sign
• Injecting too close to bony foramina where nerves exit (infraorbital foramen)
• Failing to document nerve injury complications for medicolegal purposes

Important Caveats

While the provided evidence focuses on intravitreal injection techniques 2, the principles of nerve injury apply to any periocular injection procedure. The under-eye region for tear trough augmentation has different anatomical considerations than intravitreal injection, but nerve injury mechanisms remain similar. Serious complications including cranial nerve palsies have been documented with periocular injections 1, emphasizing the need for meticulous technique and immediate recognition of complications.