A Rare Case of T1-2 Thoracic Disc Herniation Mimicking Cervical Radiculopathy

Discussion

Most thoracic disc herniations are asymptomatic.⁷ The clinical presentation of patients varies related to the level of disc herniation. Pain is the most common presentation and is usually located at the thoracic spine level with radiation in a radicular distribution. Other physical findings are unilateral or bilateral sensory loss, weakness of muscles, and bladder or bowel dysfunctions according to the affected level.¹⁰ T1-2 disc herniation is a more rare condition and can be seen with degenerative conditions or adjacent segment disease related to cervical fusion surgery.¹¹ In the literature it has been reported following cervical laminoplasty and explained as mechanical stresses which may have directly affected the T1-2 intervertebral disc following laminoplasty and may have caused disc herniation.¹² MRI, CT or myelography may be used for diagnosis. MRI is the preferred diagnosis method because of its non-invasive, high soft tissue resolution and multi-planar imaging capability features. Radiological examination must be done cautiously. The thoracic region is at the caudal end of the cervical MRI, and it is important not to miss thoracic disc herniation in this region. In literature there is one case reported with T1-2 disc herniation, which was assumed to be cervical disc disease on first radiological assessment with physical findings.¹³ Detailed and careful physical examination is just as important as radiological evaluation. T1 radiculopathy may be accompanied by C8 radiculopathy symptoms. Numbness of the fourth and fifth fingers or weakness of intrinsic muscles in the hand are accompanying symptoms with C8 and T1 radiculopathy. Cubital tunnel syndrome and Guyon's tunnel syndrome may mimic the symptoms of T1 radiculopathy. In literature, Horner's syndrome has also been reported secondary to T1-2 disc herniation.¹⁴'¹⁵

It has also been reported that spine surgeons who consider themselves experts in cervical spine surgery may have inadequate knowledge of C8 and T1 myotomes and dermatomes and may correctly identify the intrinsic hand muscles that are innervated by the C8-T1 nerve roots but not the ulnar nerve. The ulnar nerve provides sensation to the fourth and fifth fingers and medial border of the hand. The medial antebrachial cutaneous nerve provides sensation to the medial forearm. The ulnar nerve innervates all intrinsic hand muscles, except the abductor and flexor pollicis brevis, opponens pollicis, and lateral two lumbricals, which are innervated by C8 and T1 via the median nerve. By examining these five muscles, one can clinically differentiate cubital tunnel syndrome from C8-T1 radiculopathies.¹⁶ Electrodiagnostic studies may be useful in evaluating and differentiating C8, T1 and ulnar neuropathy. The muscle groups associated with a C8 radiculopathy are the first dorsal interosseous, abductor digit minimi, abductor pollicis brevis, flexor pollicis longus, and extensor indicis proprius.¹⁷ The paraspinal musculature should be examined as well because they receive motor innervation from the ipsilateral dorsal rami of the exiting root which can be compressed only at the foramen and not in a peripheral neuropathy that asymptomatic patients can have EMG changes in the cervical paraspinals.¹⁸ Abductor pollicis brevis is predominantly innervated by the T1 nerve root level, EMG changes in this muscle indicates T1 neuropathy.¹⁹

The first step of the treatment algorithm for thoracic radiculopathy is non-operative management. Traction may be applied for temporary decompression of the nerve impingement. Pharmacotheraphy may help to resolve pain in patients with radiculopathy. Nonsteroidal anti-inflammatory drugs have been used by many physicians as first-line agents in the treatment of pain. Narcotic analgesics, muscle relaxants, anti-depressants, or anticonvulsants may be used in addition to nonsteroidal anti-inflammatory drugs. In the literature opioids may be effective in the treatment of neuropathic pain.²⁰'²¹ Physical therapy may improve life quality, and selective nerve blocks target nerve root pain. Steroid injections may be the treatment option of radicular pain. Perineural injections including trans-laminar and transforaminal epidurals, selective nerve root blocks may be performed under radiographic guidance.^22,23 However, there is little high-quality evidence on the best non-operative therapy for radiculopathy, although it has been reported that a multi- modal approach may alleviate symptoms.²⁴ In the current case physical therapy and medication for pain were used but these conservative methods did not resolve the symptoms.

The second step for thoracic radiculopathy not responding to conservative treatment modalities is surgical treatment. Anterior, posterior or posterolateral approaches are the surgical treatment techniques for T1-2 disc herniation described in literature.⁷'²⁵'²⁶'²⁷ Our preferred surgical technique in posterior thoracic discectomy is costotransversectomy and discectomy. In this case costotransversectomy, hemilaminectomy, foraminatomy and discectomy at T1-2 level were performed via posterior approach. It was considered better to get through the T1-2 foramen via the posterior approach, because with the anterior approach sternotomy may be required to reach the T1-2 disc level.²⁶

T1-2 level thoracic disc herniation may be accompanied by cervical region problems and some syndromes can mimic T1 radiculopathy symptoms. Detailed physical examination is of critical importance to determine the real problem and affected level in the spine.