What is prognosis of trochlear nerve palsy (fourth nerve palsy)?

Updated: Oct 08, 2019
  • Author: Zafar A Sheik, MD, MD; Chief Editor: Andrew G Lee, MD  more...
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Prognosis of trochlear nerve palsy varies depending on etiology. Best information regarding outcome comes from cases collected at the Mayo Clinic over the past 40 years, as follows:

  • Rates of complete and spontaneous resolution of microvascular fourth nerve paresis is excellent, with 89% of patients achieving resolution within 10 months. [39]
  • Idiopathic cases also have greater than 50% likelihood of spontaneous recovery.
  • Most cases resolve within weeks to months, with the vast majority completely recovering by 6 months.
  • Some cases may resolve slowly over the course of a year.
  • Patients with head trauma were less likely to recover, yet, 44% of these patients experienced gradual and spontaneous recovery. [40]
  • Cases due to aneurysm or neoplasm were least likely to have functional recovery.

Because patients have good fusional abilities, surgery generally produces excellent results. Wang et al reported an “excellent” surgical outcome in 74% of patients and a “good” surgical outcome in 23% when evaluating degree and pattern of vertical deviation and degree of oblique muscle dysfunction. [33] Plager reported a nearly 90% success rate with his surgical algorithm. [32] Mitchell and Parks also reported excellent results in correcting excyclotorsion using modified Harada-Ito procedure. [35]

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