Itraoperative wake-up test during surgery for severe ossification of ligamentum flavum

Abstract

Objective To assess the efficacy and safety of intraoperative wake-up test during surgery for ossification of the ligamentum flavum(OLF). Methods Between June 2004 and June 2010,35 patients(23 males and 12 females,at age range of 32-71 years,mean 50.5 years) with OLF underwent posterior decompressive laminectomy and excision of OLF.The operation wag performed on the cervical vertebrae in four patients,on the thoracic vertebrae in 24 and on the lumbar spine in seven,with monosegmental OLF in 14 patients and multisegmental OLF in 21.The outcomes were evaluated using Japanese Orthopaedic Association (JOA) scale. Results The operation lasted for mean 190 minutes (120-260 minutes),with the blood loss for mean 350 ml (220-520 ml)and the mean 2.4(1-5) lamin receiving decompression.The follow-up period ranged from 6 to 72 months (mean 29.5 months).The JOA score was improved from 4.302±1.023 preoperatively to 8.327±1.032 at the final follow-up (P<0.01).The neurological symptoms was aggravated during operation in three patients,for whom the muscles force recovered gradually in two patients but one showed no change after special measures.No serious complication was found in the other patients postoperatively. Conclusions The wake-up test can serve as an effective monitoring during the procedure ofthe decompressive laninectomy in the patients with severe OLF and decrease the occurrence of neurologic deficit complications. Key words: Ossification; Ligmentum flavum; Imninectomy; Wake-up test