very chronic axon loss brachial plexopathy, caused by compromise of the distal C8 anterior primary ramus or proximal lower trunk fibers by a congenital band extending from a rudimentary cervical rib to the first thoracic rib; rare disorder, found mostly in young to middle-aged women, which presents with unilateral hand wasting and weakness, particularly involving the lateral thenar eminence; sometimes accompanied by intermittent discomfort along the medial forearm and hand. SYN: cervical rib and band syndrome, classic neurologic cervical rib syndrome.