Herniated disc (herniated nucleus pulposus) and back pain

A disc herniation is a prolapse of the central substance of the disc through the surrounding ring. Pain occurs when the disc protrusion causes trauma and inflammation of adjacent tissues (e.g., the posterior longitudinal ligament). When the disc meets a nearby spinal root, radiculopathy with paresthesia and muscle weakness in the innervation zone of the damaged root develops. Diagnostics include mandatory CT or MRI (a more informative method). Treatment in mild cases consists of prescribing NSAIDs (e.g., diclofenac, lornoxicam) and other analgesics (tizanidine, baclofen, tramadol) if necessary. Bed rest (long-term) is rarely indicated. With progression of neurological deficit, intractable pain or sphincter dysfunction, urgent surgical intervention (discectomy, laminectomy) may be required.

The vertebrae are connected to each other by a cartilaginous intervertebral disc consisting of an outer fibrous ring and an inner nucleus pulposus. Degenerative changes (after or without trauma) cause the nucleus pulposus to bulge or break through the fibrous ring in the lumbosacral or cervical region. The nucleus is displaced posteriorly or posteriorly and laterally into the extradural space. Radiculopathy occurs when a herniation compresses or irritates a nerve root. A posterior protrusion may compress the spinal cord or cauda equina, especially with congenital narrowing of the spinal canal (spinal stenosis). In the lumbar region, more than 80% of disc herniations compress the L5 or S1 nerve roots, while in the cervical region, the C6 and C7 roots are most often affected. Often, a disc herniation does not cause any symptoms and is a finding on MRI of the spine and spinal cord.

Discogenic pain is much less common than myogenic pain, but is not uncommon. There are several reasons for this: vascularization of intervertebral discs decreases during ontogenesis, already at the end of the first decade of life, tears form on the fibrous ring of the cervical intervertebral discs, and at the end of the second decade of life, progressive dehydration of the colloid nucleus begins. In the future, a rupture of the fibrous ring with the loss of fragments of the pulpous nucleus into the spinal canal is possible.

Discogenic pain has its own clinical features. The first characteristic sign is an increase in pain with movement, a decrease at rest. This is most clearly seen in lumbar disc pathology. As walking (movements) continue, the patient notes a progressive increase in pain, localized more often along the midline or with minor lateralization, the appearance of scoliosis (or aggravation of existing scoliosis). The nature of the pain is pressing, bursting. But if with protrusion of lumbar discs the horizontal position is optimal, then patients with cervical discogenic pain often experience an increase in pain in the lying position, which forces them to sleep in a semi-sitting position.

A characteristic sign may also be sclerotomic irradiation of pain. Sclerotomic pain, described by patients as deep, bursting, localized in the bone, is often the cause of diagnostic errors. At the initial stage of disc protrusion, when clinical signs of radicular compression are absent, and the patient complains of pain in the scapula, or shoulder, or shin, doctors often forget about the possibility of sclerotomic pain, which has a source in the spinal canal, and concentrate attention and manipulations on the area of projected pain.

Changes in the configuration of the spine and forced posture are a common sign of discogenic pain. For the lumbar region, this is scoliosis, which worsens when bending over; for the cervical region, this is a forced position of the head and neck. Significant limitation of spinal mobility due to severe pain in one or another region more often indicates pathology of the disc than other structures of the spinal motion segment. Local soreness and increased pain with push palpation of the spinous process or percussion of the spinal motion segment are also characteristic signs of actual disc protrusion.

One of the important differential diagnostic criteria for discogenic conflict in the spinal canal (radiculoischemia) is the good effect of Aminophylline (10 ml of a 2.4% solution intravenously slowly or by drip).

The only method that allows assessing the condition of the disc is magnetic resonance imaging (MRI), therefore, in case of back pain, MRI should be a mandatory component of the examination standard. In addition to the size of the protrusion, MRI also allows assessing the severity of perifocal changes in the spinal canal and conducting differential diagnostics with neoplasms in the spinal canal.

The pathogenesis of discogenic pain does not differ from the pathogenesis of other somatogenic pain. Rupture of the fibrous ring with protrusion of the nucleus pulposus is accompanied by traumatic injury to the posterior longitudinal ligament or its rupture (clearly defined on MRI). Irritation of mechano-nociceptors and the occurrence of aseptic inflammation cause the initiation of a nociceptive flow from the area of disc protrusion. If a disc herniation comes into conflict with spinal nerves, a rootlet (rootlets), then neuropathic pain joins somatogenic pain. In the presence of symptoms of "prolapse" manifested by corresponding sensory or motor disorders, the diagnosis of root compression is not difficult. Difficulties arise in the absence of these symptoms. As a rule, "radicular" pain radiates along the corresponding dermatome or sclerotome. As a rule, the impact on the root is accompanied by a reflex muscle-tonic reaction, which often takes the doctor's thoughts away from the spinal canal to the periphery. Thus, compression of the cervical roots is often complicated by a pronounced spasm of the scalene muscles, compression of the lumbar - the piriformis muscle. And these muscle-tonic syndromes can dominate the clinical picture for a greater or lesser time. The optimal method of instrumental diagnostics of radicular pathology should be recognized as electromyography, which, unfortunately, has not yet received due distribution in everyday clinical practice.

[ 1 ], [ 2 ]

Diagnosis and treatment of disc herniation

MRI (more informative) or CT of the clinically affected area of the spine is necessary. Electromyography can help to clarify the affected root. Since asymptomatic disc herniations are quite common, the physician should carefully compare the results of the MRI study with clinical data before considering invasive procedures.

Because more than 95% of patients with disc herniations recover without surgery within 3 months, treatment should be conservative unless the neurologic deficit is progressive or severe. Heavy or vigorous exercise is contraindicated, but light activity (eg, lifting 2 to 4 kg) may be permitted if tolerated. Prolonged bed rest is contraindicated. NSAIDs (eg, diclofenac, lornoxicam) and other adjuvant analgesics (eg, tizanidine or tramalol) may be used as needed to reduce pain. If lumbar radiculopathy results in persistent or severe objective neurologic deficits (muscle weakness, sensory disturbances) or severe intractable radicular pain, invasive treatment may be considered. Microdiscectomy and laminectomy with surgical removal of the herniated material are usually the treatments of choice. Dissolution of hernial material by local injection of chemopapin is not recommended. Acute compression of the spinal cord or cauda equina (eg, causing urinary retention or incontinence) requires immediate neurosurgical consultation.

In cervical radiculopathy, urgent surgical decompression is required when symptoms of compression (spinal cord; or the surgical method is chosen when conservative treatment is ineffective.

[ 3 ], [ 4 ]

Myths about the treatment of discogenic pain

"A disc herniation can be reduced". An extremely dangerous misconception. (which some doctors cultivate consciously or unknowingly. Back in the late 80s of the last century, Professor V.N. Shevaga in Lvov conducted a series of clinical experiments on direct digital "reduction" of a disc herniation during a neurosurgical operation. Despite the complete relaxation of the patient (anesthesia, muscle relaxants), the creation of traction for the upper and lower ends of the body, the reduction of the disc herniation did not occur. He reported on this at congresses of vertebro-neurologists. However, the misconception is still alive. In the best case, traction methods are used to "reduce" the hernia, in the worst case - manipulations on the disc.

"A disc herniation can be dissolved." Attempts to lyse a disc herniation with proteolytic enzymes (papain) were made in the second half of the last century by representatives of the Novokuznetsk and Kazan schools of vertebroneurologists. However, they all ended in failure. A person who has once seen an intervertebral disc will understand that a proteolytic enzyme introduced to lyse a herniation must first lyse all the remaining contents of the spinal canal, and only then the disc herniation. However, commercial attempts to accomplish the impossible continue.