Cervical herniated disc results in posterior or posterolateral protrusion of the intervertebral disc, most commonly in the C6-C7 segments of the cervical spine. Causes include spinal degeneration and sometimes trauma. Patients may be asymptomatic, but nerve root compression can give rise to symptoms such as pain, paresthesia, and neck stiffness. The diagnosis is made with imaging studies, while treatment includes supportive measures, surgery and physical therapy.
Presentation
Clinical presentation almost solely depends on the nerve root compressed by the protruded disc. General symptoms include pain during neck movement as well as neck stiffness and limitation in the range of motion. The most common sites of herniated cervical disc are C6 and C7 segments with ipsilateral involvement. C6 radiculopathy presents with pain at the tip of the shoulder and trapezius, which can radiate to the thumb, together with weakness of the biceps muscle, as the musculocutaneous nerve, which is responsible for innervation of this muscle, arises from the brachial plexus and the C6 root. Other symptoms include reduced biceps brachii and brachioradialis reflexes, with or without paresthesia and reduced sensory function. In the case of C7 nerve root compression, axillary pain and pain over the scapular region, often radiating to the middle finger may be reported [9]. The radial nerve arises from the C7 nerve root, which provides motor innervation to triceps brachii muscle and in patients with compression of this nerve, weakness of triceps brachii with reduced reflexes can be observed. Deltoid muscle weakness implies that there is nerve root compression at some higher segments, such as C4 or C5, while weakness of the little finger indicates the lesion involves the ulnar nerve and the C8 segment. Symptoms such as paresthesias, spastic paresis of the lower limbs, and even quadriplegia may be observed, as a consequence of compression of the spinal canal [8]. Under such circumstances, emergent treatment to prevent permanent damage is indicated.
Workup
The diagnostic workup of patients with suspected herniated disc, regardless of its location, should start with a thorough physical examination, which can approximately identify the location of the lesion. A complete neurological examination, including sensory testing and muscle strength evaluation, can point to the nerve root which is affected, but a definite diagnosis is obtained through imaging studies. CT or MRI can identify the herniated disc and establish which adjacent structures are damaged [10]. Once the diagnosis is established, imaging studies are the primary means of determining appropriate therapy.
Treatment
Treatment principles significantly depend on the severity of nerve root compression. Patients who experience mild symptoms may not require therapy as symptoms tend to regress spontaneously [11]. A conservative approach using NSAIDs including acetaminophen or other pain-relieving drugs, together with physical therapy is recommended in these patients. The goal of physical therapy is to improve and maintain the strength of the neck and back muscles as well as to improve body posture and relieve pain. It should be performed under supervision to prevent harm and worsening of the pain.
For patients with more severe symptoms, such as spastic paresis and paraplegia, or those who fail conservative therapy, surgical treatment may be necessary. Removal of herniated discs, laminectomy, and decompression of the spinal cord are just one of the many surgical procedures that can be performed [12]. Surgery is performed as soon as there are clear indications, such as the development of acute spinal cord compression or quadriplegia. The main reason is that significantly better outcomes are observed when surgical treatment is performed early [12].
Prognosis
The prognosis depends on the severity of herniation and involvement of nerve roots and the spinal canal. The majority of patients recover within three months with only conservative therapy [8], meaning that this condition has a good overall prognosis. However, cases that include severe neurological impairment and compression of the spinal cord by the herniated disc, the prognosis may be significantly worse without prompt surgical treatment. For these reasons, a detailed workup to identify the magnitude of the injury and to determine optimal therapeutic strategies is essential to achieve good outcomes.
Etiology
Herniation of discs in the cervical, but also other parts of the spine, occurs as a result of protrusion of the nucleus pulposus through the outer fibrous ring of the intervertebral disc, annulus fibrosus [1]. It is known that progressive degenerative changes in the intervertebral discs are the main causes that lead to this condition, while trauma and prolonged stress to these areas have also been mentioned as potential causes. The protruded nucleus of the disc may not cause significant damage to adjacent structures, but it may cause nerve root compression, or radiculopathy, which can present symptoms that are significantly debilitating. Both genetic and environmental factors have been implied in the pathogenesis of this syndrome, but further evidence is necessary to establish their exact roles [2].
Epidemiology
Cervical herniated disc is interpreted as the most common cause of radiculopathy, but its exact prevalence rates in the general population remain unknown. Prevalence rates in asymptomatic patients are established to be much higher among the elderly than in young and middle-aged adults [5], implying that advanced age is a significant risk factor. The most common sites of herniation are the C6 and C7 segments, but herniation may occur at any segment of the cervical spine and sometimes more than one disc may be involved [6]. Neither gender nor ethnic predilection has been established.
Pathophysiology
The pathogenesis of cervical herniated disc primarily involves progressive degeneration of the skeletal spine. Over time, structural integrity of the discs, as well as the vertebrae becomes compromised and more prone to injury. Under physiological conditions, the intervertebral disc is composed of two parts - the outer ring, annulus fibrosus, which serves as a protective layer of fibrous tissue and cartilage, while the central part, nucleus pulposus, a gelatinous structure made from water and collagen fibers, serves to compensate pressure changes between the vertebrae. Annulus fibrosus degenerates over time, which leads to development of small tears in its layers. It is thus unable to perform its function leading to herniation of the nucleus pulposus through the fibrous coat [7]. The herniation may be asymptomatic, meaning that damage to adjacent tissues is insignificant, when the vertebral column is kept firm. As numerous nerves arise from nerve roots located adjacent to the intervertebral disc, however, nerve compression is a common event in these patients, which leads to neurological symptoms that depend on the nerve root affected.
Prevention
Herniation of the cervical disc is a progressive condition resulting due to degenerative changes in the discs and vertebrae. Some general principles of prevention include maintaining physical activity and strength of the back muscles which will provide adequate stability to the spinal canal. Additionally, patients with symptoms should report early so that diagnosis can be made in the early stages. This significantly reduces chances of developing sequelae of this condition.
Summary
Cervical herniated disc is a condition that demarcates protrusion or prolapse of the intervertebral disc at the level of the cervical spine. In the majority of cases, progressive degeneration of the disc is the cause, while trauma may or may not be associated with this condition. The pathogenesis involves tears in the annulus fibrosus, the outer fibrous part of the disc, which leads to prolapse of the inner part, the nucleus pulposus [1]. Usually, posterolateral or posterior displacement occurs and causes radiculopathy due to nerve root compression. In fact, disc herniation is the most common cause of radiculopathy. Genetic factors, as well as advanced age, have been determined to play a role in herniation of cervical discs, while its association with concomitant development of lumbar disc herniation has been established, thus hypothesizing a systemic development of these pathological processes [2]. In most cases the C6-C7 levels are affected and depending on the spinal level, different symptoms may be present. In general, patients most commonly report pain during neck movement, together with other accompanying ipsilateral symptoms. C6 radiculopathy manifests with pain at the tip of the shoulder and in the region of the trapezius muscle, upper arm weakness (specifically the biceps and the brachioradialis muscles) and reduced reflexes together with paresthesias and sensory loss. On the other hand, C7 nerve root involvement manifests as reduced strength of triceps muscle, as well as reduced triceps reflex, together with pain in the axilla that can radiate to the middle finger. Other, more severe symptoms, such as spastic paresis of lower limbs, or even quadriparesis may occur when the cervical spinal cord is compressed by the herniated disc, which is why a prompt diagnosis and therapy may significantly reduce morbidity in many patients. The diagnosis is made through imaging studies, such as computed tomography (CT) or magnetic resonance imaging (MRI), which can clearly identify at which level the herniation has occurred [3]. Depending on the severity of symptoms and damage done by the protruded disc, treatment principles may vary. Sometimes, symptoms may resolve on their own, without any form of treatment. In mild cases, conservative therapy with administration of non-steroidal anti-inflammatory drugs (NSAIDs) such as acetaminophen, together with appropriate and regular physical therapy may relieve symptoms completely [4]. In case of severe radiculopathy and spinal cord compression, however, early surgical treatment is indicated, in an attempt to prevent significant damage to the affected nerves which can lead to permanent paresis.
Patient Information
Herniated cervical disc is a condition that most commonly occurs in elderly individuals, as a result of progressive degenerative changes in the intervertebral discs in the neck. Normally, there is an intervertebral disc between each vertebra. It serves to absorb stress and pressure created by movement and other activities. It consists of two parts, the central part called the nucleus pulposus, which is composed of water and collagen and the outer part, annulus fibrosus, which is composed of fibrous tissue and serves as a protective barrier for the central part. As time progresses, the outer part begins to degenerate and disrupts its normal structure, which leads to protrusion of the nucleus pulposus through it. Once the disc breaches the outer fibrous layer, it is termed herniation. As it protrudes, it can damage several structures that are in the vicinity, most commonly the nerve roots that arise from the spinal cord in the region of the neck, which is why patients often have symptoms that are related to the affected nerve root. However, milder forms of this disease may have an asymptomatic course. When symptoms are present, pain is most frequently reported, when attempting to move the neck. Other symptoms may include weakness of the muscles of the arm and shoulder, including deltoid, triceps, and biceps, as well as reduced muscle reflexes and sensitivity to touch. In more severe cases, the herniated disc may compress the spinal cord directly and lead to symptoms such as paralysis of two or even all four limbs. Because nerve damage may be permanent, a prompt diagnosis should be made, which is performed by conducting imaging studies. Computed tomography (CT scan) or magnetic resonance imaging (MRI) can identify the exact location of the herniated disc and evaluate which adjacent structures are affected. Treatment principles depend on the severity of the nerve damage. In patients with occasional mild symptoms, a conservative approach including administration of non-steroidal anti-inflammatory drugs such as acetaminophen combined with physical therapy may be sufficient. Surgical therapy is indicated for patients that present with severe symptoms, and for those in whom rapid progression is observed. Surgery is aimed at removing the elements of the disc that have protruded and decompress the nerve roots damaged. This condition has a good prognosis, as the majority of patients may experience regression even without therapy. However, as herniation of the cervical disc may cause permanent nerve damage, early and proper treatment is vital in ensuring good outcomes.
References
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