Arachnoid cyst is a benign lesion comprising about 1 % of spinal tumors and generally affects the thoracic region . Clinical manifestation usually includes progressive spastic or flaccid paraparesis, sensory deficits, bowel incontinence and bladder incontinence [4, 5]. The severity of symptom depends basically on cyst size [4, 7]. The size of SEACs reported usually involves several spinal segments ranging from 3 to 5 [1, 4, 8, 9]. In our case, there were 8 segments related with the SECA, which might be the longest SEAC that have been reported up to now. The laminas became extremely thin because of the long-term compression. The patient also exhibited typical symptoms of myelopathy.
Several surgical options for treatment of SEAC have been proposed. The conventional laminectomy was performed by different tools such as bone osteotome or T-saw [1, 10, 11]. Those methods provide excellent exposure and allow available space for safe excision of lesions. However, those techniques usually take a long time and moreover, such a wide laminectomy can easily injure the cord or rupture the cyst. In addition, lack of laminoplasty sacrifices the protective role of the posterior elements . In our case, we used craniotome to perform the laminectomy. The author has been using this technique for two years and successfully excised hundreds of spinal lesions. Based on our experience, the advantages include less bleeding, less operating time and better maintenance of spinal stability. Because of the protective plate on top of the craniotome, the risk of damage to the dura and the wall of cyst may be significantly decreased. The total operating time was two and a half hours and the blood loss was approximately 250 ml despite the immensity of the cyst. The cyst was intact after laminectomy, which could allow surgeon to identify anatomical structures easily and also be helpful to achieve the total resection.
The formation of epidural scar, especially the incidence of kyphotic deformity after conventional laminectomy has been reported to be 33–100 % [8, 11, 12]. Laminoplasty has been recommended to prevent these complications especially for cysts located on thoracic or lumbar spine [6, 11, 12], and also helps to avoid excessive posterior elements loss. Titanium mini-plates were used for stabilizing laminas into their original positions in laminectomy. However, in our case 12 titanium cables were used because the author believed titanium cables provided better undergoing tension compared to tianuim mini-plates . There was no kyphotic deformity or compression on the spinal cord based on the MRI taken 1 year after the surgery, which might be the evidence supporting this viewpoint.