Sensory and motor function altered by C8 radiculopathy
The classification of cervical radiculopathy relates to the cervical nerves involved, each one producing distinct symptoms according to their respective dermatomes. The illustrations represent above, the dermatome sensory areas (blue), and below the muscles affected by motor dysfunction of the respective cervical nerves. C5 radiculopathy: weakness to the deltoid and biceps muscles of the upper arm; reduced biceps reflex.C6 radiculopathy: weakness in the extension of the brachioradialis muscle (elbow flexion) and wrist (extension) including brachioradialis reflex. Thumb paresthesia (pins and needles sensation).C7 radiculopathy: weakness of the triceps muscle (elbow extension) and wrist flexion, reduced triceps reflex. Paresthesia in the index, middle and ring fingers. C8 radiculopathy: weakness in flexion of the distal phalanges of the middle and index fingers. Paresthesia of the little finger.T1 radiculopathy: affects the motor function of the interossei muscles of the hand. Altered sensation at the ulnar side of the forearm.Reduced sensibility may occur in the respective dermatomes of C5 to T1.
Medical examination begins with the patient™s history including previous injuries, diseases and physical activities relative to profession and sport. The examiner determines the increase or relief of symptoms when the patient actively moves the neck. It is helpful to run the Spurling test, shoulder abduction test (lift the arm over head relieves symptoms), and vertical head traction test. Medical evaluation also includes the neurological assessment of sensory and motor functions as well as reflexes. X-rays and CT scans are taken to determine the alignment of the vertebrae, the presence of disc herniation, the dimension of the spinal canal and the growth of bone spurs. MRI of the neck is useful to detect nerve compression, bulging /herniation of the disk, the diameter of the spinal canal and the integrity of the spinal cord. Electromyography and nerve conduction studies help distinguish cervical radiculopathy from other diseases affecting the nerves (diabetes). Nerve root block can be used as a diagnostic tool. It consists in the local injection of anaesthetics, which improves pain if the specific nerve is affected.The examiner may also consider differential diagnosis for a patient™s symptoms like: brachial plexus injury, cervical disc injury, cervical facet joint syndrome, cervical spine injuries, rotator cuff injury of the shoulder, and carpal tunnel syndrome.