Introduction: Surgery for intrinsic brainstem lesions is associated with a significant rate of post-operative neurological complications. Although many of the complications associated with entry into the brainstem are temporary, few studies have evaluated long-term deficits associated with resection of brainstem pathology via defined safe entry zones. We reviewed our experience with surgery for cavernous malformations in the brainstem and identified morbidity associated with the use of defined safe entry zones.
Methods: Between January 2008 and January 2013 the senior author operated on 92 consecutive patients with cavernous malformations of the brainstem. Patient characteristics, imaging results, clinical examination and long-term follow-up for these patients were retrospectively reviewed.
Results: Ninety-two patients (47 female, 45 male) with an average age of 37.6 years (median, 38 years; range, 9 months – 77 years) were included in this study. Cavernous malformations were located in the midbrain (n=18), pons (n=66), medulla (n=5) and pontomedullary junction (n=2). Fifty lesions were superficial (abutting the pia) and 42 were deep. Safe entry zones included the lateral pontine zone (n=32), the lateral medullary sulcus (n=14), the median sulcus of the 4th ventricle (n=10) and the peritrigeminal zone (n=10). All patients who presented with pre-operative deficits experienced temporary worsening of these deficits. At follow-up (mean, 20.5 months), 15 patients had new or persistent neurological symptoms.
Conclusions: Safe entry zones for surgical excision of brainstem cavernous malformations may temporarily worsen pre-existing neurological deficit, but persistent or new deficit at follow-up is uncommon.
Patient Care: Identifying the safe entry zones of brainstem surgery will help minimize surgical morbidity.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of safe entry zones into the brainstem for the resection of cavernous malformations and 2) Discuss, in small groups, the morbidity of these procedures in relation to the natural history of the disease.