Herniated nucleus pulposus is prolapse of an intervertebral disk through a tear in the surrounding annulus fibrosus. The tear causes pain due to irritation of sensory nerves in the disk, and when the disk impinges on an adjacent nerve root, a segmental radiculopathy with paresthesias and weakness in the distribution of the affected root results. Diagnosis is usually confirmed by MRI or CT. Treatment of mild cases is with analgesics, activity modification, and physical therapy. Bed rest is rarely indicated. Patients with progressive or severe neurologic deficits, intractable pain, conservative treatment failure, or cervical myelopathy may require immediate or later elective surgery (eg, diskectomy, laminectomy).
Spinal vertebrae are separated by fibrocartilaginous disks consisting of an outer annulus fibrosus and an inner nucleus pulposus. When degenerative changes (with or without trauma) result in protrusion or rupture of the nucleus through the annulus fibrosus in the lumbosacral or cervical area, the nucleus is displaced posterolaterally or posteriorly into the extradural space.
Radiculopathy occurs when the herniated nucleus compresses or irritates the nerve root. Posterior protrusion may compress the cord in the cervical, thoracic, or upper lumbar spine or the cauda equina, especially in a congenitally narrow spinal canal (spinal stenosis). In the cervical spine, the C6 and C7 nerves are most commonly affected.
Herniated disks are common.
Symptoms and Signs of Cervical Herniated Nucleus Pulposus
Herniated disks often cause no symptoms, or they may cause symptoms and signs in the distribution of affected nerve roots. Pain usually develops suddenly, and neck pain is typically relieved by rest and modification of activity. In contrast, nerve root pain caused by an epidural tumor or abscess begins more insidiously, and neck pain is worse at night while in bed.
In patients with cervical disc herniations, there can be pain with flexion or combined extension and rotation, which can radiate to the upper extremities. Muscle weakness, numbness, and paresthesias can also be present in the upper extremities.
Diagnosis of Cervical Herniated Nucleus Pulposus
MRI or CT
Diagnosis is usually suspected based on history and physical examination findings and confirmed by MRI or CT.
Physical examination should assess cervical spine movement and how it relates to the patient's symptoms. Neurological examination should include assessment of motor strength, sensation, and deep tendon reflexes. Passively extending the cervical spine, rotating the head to the side of the patient symptoms, and applying axial compression (Spurling or nerve compression test) may produce radicular pain in the upper extremity on the side to which the head is rotated.
MRI or CT can identify the cause and precise level of the lesion. Rarely (ie, when MRI is contraindicated and CT is inconclusive), CT myelography is necessary. Electrodiagnostic testing may help identify the involved root.
Because an asymptomatic herniated disk is common, the clinician must carefully correlate symptoms with MRI abnormalities before invasive procedures are considered.
Treatment of Cervical Herniated Nucleus Pulposus
Conservative treatment initially
Invasive procedures, sometimes including surgery, if neurologic deficits are progressive or severe
Because a herniated disk desiccates and shrinks over time, symptoms tend to abate regardless of treatment. Up to 85% of patients with back pain—regardless of cause—recover without surgery within 6 weeks.
Conservative treatment
Treatment of a herniated disk should be conservative, unless neurologic deficits are progressive or severe. Heavy or vigorous physical activity is restricted, but ambulation and light activity (eg, lifting objects < 2.5 to 5 kg [about 5 to 10 lb] using correct techniques) are permitted as tolerated; prolonged bed rest (including traction) is no longer indicated.
Physical therapy and home exercises can improve posture and strengthen neck muscles and thus reduce spinal movements that further irritate or compress the nerve root. Traction can relieve symptoms in the cervical spine.
Invasive procedures
Invasive procedures should be considered for the following:
Persistent or worsening neurologic deficits, particularly objective deficits (eg, weakness, reflex deficits) due to cervical radiculopathies
Acute compression of the spinal cord, causing myelopathy
Severe, intractable nerve root pain or sensory deficits
Immediate surgical evaluation is needed if clinical findings of spinal cord compression correlate with MRI abnormalities.
Anterior diskectomy and cervical fusion are the most common treatments for cervical radiculopathies. Laminectomies are not performed alone without posterior fusion due to the complication of cervical kyphosis.
Dissolving herniated disk material with local injections of the enzyme chymopapain is not recommended.
Lesions acutely compressing the spinal cord causing myelopathy require immediate surgical evaluation (see diagnosis of spinal cord compression).
If cervical radiculopathies are accompanied by signs of spinal cord compression, surgical decompression is needed immediately; otherwise, it is done electively when nonsurgical treatments are ineffective.
Key Points
Cervical herniated disks are common and usually affect nerve roots at C6 and C7.
If symptoms develop suddenly and neck pain is relieved with rest, suspect a herniated disk rather than an epidural tumor or abscess.
Recommend analgesics, light activity as tolerated, and exercises to improve posture and strength; however, if pain or deficits are severe or worsening, consider invasive procedures.
