Giant spinal nerve sheath tumours - Surgical challenges: case series and literature review

Background: Giant nerve sheath tumours (GNST) are rare and literature on their management is scant. Spinal GNST present as a surgical challenge due to the involvement of anatomical regions often outside the "comfort zone" of a spinal surgeon. This case series aims to identify challenges in the surgical management of GNSTs. Methods: Retrospective case note review of all spinal GNST cases from 2010 to 2016 managed in Sheffield Teaching Hospitals identified 8 patients, 3 of whom were incidental findings (kept under surveillance) and were excluded. 5 cases were treated surgically. Data collected included patient demographic, presenting symptom(s), radiological data, surgical approach to the tumour and challenges encountered, histopathology report and follow up. Results: Our cohort consisted entirely of females (N = 5) with a mean age of 56.4 years (range 45-70). Imaging studies and histopathological diagnoses confirmed 5 GNSTs (four benign schwannomas and one ganglioneuroma). A Single-stage anterior approach was adopted for three patients while a combined anterior-posterior approach was adopted for the remaining two. In one patient, a posterior approach was initially planned, but this was abandoned and converted to an anterior approach following onset of acute superior vena cava (SVC) syndrome secondary to SVC compression by the giant tumour on prone positioning of the patient. PET imaging of case 3 showed intense tracer uptake consistent with malignancy, however histology confirmed WHO grade 1 Schwannoma. The other three non-operated GNSTs are kept under yearly radiological and clinical surveillance. Conclusions: GNSTs are surgically challenging as they often invade territories that are beyond the comfort zone of one single specialty. A multidisciplinary approach with careful pre-operative surgical planning is recommended. Patients in whom a posterior approach is planned should have a trial of prone positioning pre-operatively. Careful interpretation of FDG-PET imaging is recommended due to the possibility of false positive result.