Table 1. Shamblin classification of carotid body tumours.

Group	Tumour size	Relationship with carotid arteries	Surgical treatment
Group I	Relatively small	Minimally attach to the carotid arteries	Surgical excision is not difficult
Group II	Larger	Moderately attach to the carotid arteries	Often require a carotid shunt
Group III	Very large	Encase the carotid arteries	Often require arterial resection and grafting