Acute disc

This occurs in young individuals in the absence of other major degenerative spine disease. In acute presentations there is often a history of recent injury or straining, for example lifting. This results from herniation of the nucleus pulposis through a rupture in the annulus fibrosis, a so-called ‘soft disc’ (Fig. 1).

Fig. 1 Acute herniation – the ‘soft disc’. This leads to (1) cord compression or (2) radicular compression.

Spondylosis

In older adults, spondylotic disease may present with radiculopathy, usually at similar levels, but somewhat more frequently can affect other cervical and lumbar levels. The discs initially dehydrate, thus losing height and the disc annulus prolapses. This leads to osteophytic outgrowths on the vertebral bodies and instability of the apophyseal joints, which then hypertrophy. The osteophytes and hypertrophied facet joints may then compress the nerve roots, producing a radiculopathy, or the spinal cord, producing a myelopathy.

Other rarer causes

Tumours may cause radiculopathy at any level and may be primary nervous system tumours arising on the nerve root (e.g. neurofibroma or meningioma) or spinal bony metastases compressing the nerve root (Figs 2 and 3). Common sources of secondaries are tumours of breast, bronchus, prostate, kidney, thyroid and lymphoma. An apical lung tumour (Pancoast tumour) causes wasting of small muscles of the hand (T1) and a Horner’s syndrome.

Fig. 2 MRI showing an acute disc herniation compressing the lumbosacral canal (arrow).

Fig. 3 An MRI of the lumbosacral spine showing a vertebral secondary leading to collapse of the vertebral body and compression of the cauda equina.

Inflammatory conditions may cause radiculopathy; the most common is shingles (herpes varicella zoster virus) infection (p. 100). Rarely, radiculopathy can be due to inflammatory or malignant meningitis.