14 March 2019 Autor : Álvaro Lima The lumbar spine is made up of 5 vertebrae, which are separated by cartilaginous discs. These discs are made up of an outer fibrous ring and a gel-like centre —the nucleus pulposus . As the spine bends, twists or extends, they undergo changes in shape. These cartilage ‘shock absorbers’ enable the spine to bear and disperse the load through its multiple levels, maintaining the stability and flexibility required to perform daily tasks. What are the causes of a herniated lumbar disc? Depending on the ageing process and the load exerted on the intervertebral discs, they undergo a degenerative process that consists of: Loss of their high water content; Loss of elasticity and the ability to cushion the effects of load bearing. Magnetic resonance studies show that by the age of 35, about 30% of the population will show disc degeneration of some degree or another. By the age of 60, this percentage will be around 90%. What are the consequences and symptoms of a herniated lumbar disc? In most cases, this degenerative process is asymptomatic , but in many situations it can give rise to incapacitating lumbar pain. In some cases, during the process of disc degeneration the fibrous ring breaks and a fragment of the nucleus pulposus is displaced into the spinal canal, where the nerve roots are located, leading to a herniated disc. When this fragment presses onto a nerve root, the patient experiences lumbar pain, with irradiation to the leg and the foot. Such situations may arise insidiously or may be triggered by: Sudden movements; Stress overload on the cervical spine. Complaints of lumbar pain with irradiation to the lower limbs usually occur after physical exertion , such as lifting heavy objects, bending or rotating the torso. The pathway of the pain is related to the compressed nerve root in the spinal canal. The most common symptoms in lumbar disc disease are as follows: Continuous or intermittent lumbar pain that is exacerbated by movement, coughing, sneezing and standing still; Spasm of the lumbar muscles; Sciatic pain - pain that irradiates to the lower limbs, affecting legs and feet; Lack of strength in foot movements; Numbness in legs and feet; Reduced knee and heel reflexes; Urinary or anal sphincter control disorders. In rare cases, if the herniated disc is very bulky , the patient may experience: Difficulty in moving; Lack of balance; Inability to control vesical and anal sphincters. How is a herniated lumbar disc diagnosed? Several complementary methods may be used in the diagnosis of a herniated lumbar disc: Simple radiography: this is the imaging method most commonly used to diagnose dislocation or fractures after lumbar trauma. In degenerative disease, its capacity for providing information is limited and it may show a decrease in disc space and the formation of osteocytes on the margins of the vertebral bodies; Computer tomography (CT): is the best examination for diagnosing changes in bone structures. It also enables observation of changes in the intervertebral disc, the dimensions of the spinal canal and assessment of the degree of disc projection into the canal; Magnetic Resonance (MRI): is the best examination for assessing the neurological structures, spinal cord and roots of the cauda equina and their relationship with the protrusion or extrusion of disc fragments; Myelography: is the examination carried out when it is not possible to perform an MRI and consists of a contrast injection into the dural sac followed by a CT scan. It allows assessment of the dimensions of the spinal canal and any areas of spinal or root compression; Electromyography: This studies the function of peripheral nerves in situations in which there have been motor or sensory changes in the limbs, allowing for a differential diagnosis between peripheral neuropathy and affectation of the nerve root as a result of compression at the spine. Spinal herniation is one of the areas dealt with by neurosurgery and orthopaedics. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
