A Practice Pathway for the Initial Diagnostic Evaluation of Isolated Sixth Cranial Nerve Palsies

Purpose: To define a practice pathway for the evaluation of sixth-nerve palsies (SNPs) and to determine its cost—effectiveness and validity in a retrospective chart review. Methods: A Medline search of the English-language literature from 1966 to 1995 was performed to define the available clinical evidence and develop the practice pathway. The authors retrospectively reviewed 407 charts with the diagnosis of SNP seen at three centers. Information obtained included: etiologic diagnosis if known; development of new neurologic or ophthalmologic findings; and results and costs of neuroimaging studies, if performed. Results: Of the 407 patients, 98 underwent computed tomogra phy scans and 212 underwent magnetic resonance imaging of the head. Eighty cases were non-isolated, 317 were isolated SNP, and ten could not be classified from chart information. Of the 317 cases of isolated SNP, 49 were classified as traumatic; 5, congenital; 158, vasculopathic; 63, nonvasculopathic; and 42, progressive or unre solved. Following the recommendations of the practice pathway, the 158 patients clas sified as having vasculopathic SNP would not have undergone neuroimaging studies, realizing a savings of $100,000 in this study population of 407 patients. Conclusion: The recommendations of the practice pathway are supported by review of the literature and the retrospective review of these cases. However, a prospective study with a matched control group is needed to demonstrate regional and specialty-specific van ations in care and to strengthen the clinical certainty of the pathway recommendations. Key words: practice pathway; diagnostic evaluation; sixth cranial nerve palsies; oph thalmology. (Med Decis Making 1999;19:42-48)