He Didn't See It Coming: An Unusual Concussion Complication - Page #4

Working Diagnosis:
He was treated for a concussion with cranial nerve IV (trochlear) palsy and left homonymous hemianopia due to an occipital lobe injury.

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He was advised to rest from all physical and cognitive activity, including school. He was advised to wear an eye patch. He underwent visual training with occupational therapy and his headaches were treated with pain medication.

His visual field deficits and trochlear nerve palsy spontaneously resolved two months following his injury. He continues to have post-concussive symptoms eight months later including cognitive dysfunction with difficulty forming short term memories. He suffers from anxiety and depression, mild headaches and fatigue. He has been able to return to school.

Author's Comments:
The trochlear nerve is susceptible to injury due to its location. It is the only cranial nerve to exit the brain stem dorsally and it has the longest intracranial length as it courses around the brainstem to enter the cavernous sinus and orbit where it innervates the superior oblique muscle. It is injured most commonly due to head trauma or infarct. The contrecoup forces of head trauma compress it against the rigid tentorium. It is usually associated with a loss of consciousness although not in this particular case.
The visual disturbances are due to superior oblique muscle paralysis. Nearly all cases resolve within weeks up to six months. If they do not resolve, there is a surgery than can be performed to resect the inferior oblique muscle to realign the eyes.

Stiller-Ostrowski, JL. Fourth cranial nerve palsy in a collegiate lacrosse player: a case report. Journal of Athletic Training 2010;45(4):407-10
Brazis, PW. Isolated palsies of cranial nerves III, IV, and VI. Seminars in Neurology 2009;29(1):14-28
Enzenauer, RW, Hoehn, ME, and Del Monte, MA. Strabismus. Rudolph's Pediatrics, Chapter 586. McGraw-Hill Publishing; 2009.

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