Abstract:

Objective To investigate the microsurgical techniques of the excision
 of the intradural extramedullary tumors through hemilaminectomy and to illustra
te its clinical effect. Methods The clinical data of 16 patients （7 men，9 women） with intradural extramedullary tumors treated in our hospital from January
2009 to December 2011 was retrospectively analyzed.The average age was 49 years，ranging from 34-72 years.The intradural

extramedullary tumors located at the cervical level in 3 patients,thoracic in 4 patients,thoracico-lumbar in 9 patients.14 patients underwent hemilaminectomy while 2 patients were treated with laminectomy during operation.The clinical effect of hemilaminectomy was evaluated based on Frankel grade.Results
The mean bleeding volume was 300 mL (150-500 mL) and the mean duration of operation was 140 min (90-200 min).

The maximum volume of the tumor was 4.0 cm × 1.5 cm × 1.5 cm，while the minimum one was 1.5 cm
 × 1.0 cm × 1.0 cm.There were neurinoma in 11 patients，meningioma in 4 cases
 and neurofibroma in 1 case.3 cases ameliorated from Frankel grade B to C;5 case
s of Frankel grade C recovered to grade D;7 cases of Frankel grade D was improved to grade E．All the patients were followed up from 6 to 40 months with an aver
age of 23.7 months.None of the patients showed tumor recurrence and spinal instability.
Conclusion The mean bleeding volumes of the patients underwent hemilaminectomy and laminectomy are 275  and 475 mL,respectively.The advantages of th
e approach are minor invasion，less bleeding，and  retaining  the spinal
 stability.The outcome of the excision of the intradural extramedullary tumors
through hemilaminectomy is satisfactory in general．

Key words: intradural extramedullary tumors, hemilaminectomy, microsurgery, Frankel grade, spinal stability