Tip: Clarify MD's notation of CTS before coding. You currently have a single diagnosis choice when your physician documents cubital tunnel syndrome: 354.2. Your options will expand and your provider's documentation will need to be more detailed when ICD-10 goes into effect Oct. 1, 2013, however. ICD-10 options: G56.20 ��" Lesion of ulnar nerve, unspecified upper limb G56.21 ��" Lesion of ulnar nerve, right upper limb G56.22 ��" Lesion of ulnar nerve, left upper limb. Other conditions in the same classification will include G56.0x (Carpal tunnel syndrome), G56.1x (Other lesions of median nerve), G56.3x (Lesion of radial nerve), G56.4x (Causalgia of upper limb), G56.8 (Other specified mononeuropathies of upper limb), and G56.9 (Unspecified mononeuropathy of upper limb). Caution: Differences: The carpal tunnel is a narrow, rigid passageway of ligament and bones at the base of the hand. Carpal tunnel syndrome occurs when the median nerve running through this tunnel from the forearm into the hand becomes compressed at the wrist. The pressure can lead to pain, weakness, or numbness in the hand and wrist, radiating up the arm. Although painful sensations might indicate other conditions, carpal tunnel syndrome is the most common and widely known entrapment neuropathy involving compressed or traumatized peripheral nerves. Being a common condition, however, doesn't mean a note of "CTS" on the patient's chart always means carpal tunnel syndrome. Checking the affected nerve and anatomic location will help you make the correct choice.