Evaluation of neurological symptoms related to hip fracture in a 29-year longitudinal study of subacute myelo-optic-neuropathy (SMON)

Aim: Hip fracture in elderly people is a major risk factor in the deterioration of activities of daily living (ADL). The aim of this study was to investigate the incidence of hip fractures and the neurological symptoms contributing to hip fracture in patients with subacute myelo-optic-neuropathy (SMON), a drug-induced neurological disease manifesting various symptoms.<br> Methods: We investigated the incidence of hip fracture in 3,269 SMON patients with 24,187 medical check-ups from 1979 through 2007 by the SMON Research Committee in Japan. Neurological symptoms were evaluated in 80 patients who had undergone clinical examinations within 2 years before the fracture (hip-fracture group: age at examination = 75.7±8.8 years (mean±SD)), and the control group (160 SMON patients without a history of hip fracture; 76.5±10.4) were matched for age, gender, and duration of illness. Incidence of hip fracture in SMON as well as severity of visual acuity, motor and sensory symptoms, and ADL were investigated.<br> Results: A total 230 hip fractures occurred in 208 patients (6.4%) with a men-to-women ratio of 21 : 187. In comparison with the Japanese general population, SMON patients showed a statistically high incidence of hip fracture in the 50s and 60s age groups in women (p < 0.002 in both), and in those under 40 (p < 0.02) and in their 50s (p < 0.002) in men. In those with neurological symptoms related to gait, the percentage of subjects who could walk with crutches was significantly higher in the hip-fracture group (43.8%) than in the control group (28.1%) (p < 0.05). Analysis of the vibratory sensation revealed that the hip-fracture group showed a significantly higher percentage of severe impairment (51.9%) than the control group (32.0%) (p < 0.025). There were no significant differences in variance between the two groups in other clinical symptoms or ADL.<br> Conclusions: Impairment of vibration sense, a deep sensation, is more likely to be associated with falling and hip fracture than visual acuity or other neurological symptoms in SMON patients. Those persons with vibration sense disturbance, such as elderly or patients with neurological diseases, should be particularly cautious of falling.<br>