The Hoffmann parallax: a prospective study to determine the benefit of Hoffmann's sign.

Abstract

Degenerative cervical myelopathy (DCM) is the most common cause of age-related spinal cord dysfunction worldwide. Despite the widespread use of provocative physical exam maneuvers in the workup of DCM, the clinical significance of Hoffmann's sign is controversial. The purpose of this study was to prospectively assess the diagnostic performance of Hoffmann's sign for DCM in a cohort of patients treated by a single spine surgeon. Patients were divided into two groups based on the presence of a Hoffmann sign on physical examination. Advanced imaging studies were independently reviewed by four raters for confirmation of a diagnosis of cervical cord compression. Prevalence, sensitivity, specificity, likelihood, and relative risk ratios for the Hoffmann sign were calculated, with subsequent Chi-square and receiver operator characteristic (ROC) analysis to further characterize correlative findings. Fifty-two patients were included - of whom, thirty-four (58.6%) patients presented with a Hoffmann sign, and eleven (21.1%) patients demonstrated cord compression on imaging. The Hoffmann sign demonstrated a sensitivity of 20% and a specificity of 35.7% (LR = 0.32; 0.16-1.16). Chi-square analysis revealed that imaging findings positive for cord compression were proportionally greater for patients lacking a Hoffmann sign than those with a confirmed Hoffmann sign (p =0.032) ROC analysis demonstrated that a negative Hoffmann sign performed moderately well in predicting cord compression (AUC.721; p =0.031). The Hoffmann sign is an unreliable marker for cervical cord compression, and the lack of a Hoffmann sign may be more predictive of cervical cord compression.