Pinched Nerve

OVERVIEW

The spine is made up of 33 bones called vertebrae and divided into four regions: cervical (neck), thoracic (mid back), lumbar (lower back), and sacrum. The vertebrae surround the spinal cord, a thick band of nerve tissue that runs through the spine, providing 360o of protection. Each vertebral body has openings called foramen for nerves branching off the spinal cord to exit the spine and run to the hands, legs, torso, and other locations in the body. Pinched nerve is an umbrella term for any spinal condition that compresses nerves exiting the spine and causes symptoms in the region that particular spinal nerve exits to. This can include structural problems like disc herniation, spondylolisthesis, and disc degeneration or the formation of bone spurs, cysts in the spine joints, or tumors. These problems can cause narrowing of the foramen on the vertebral bodies, leading to symptoms below.

TYPES

A pinched nerve is a form of compression that applies to nerves that exit from the spinal cord through an opening in the vertebrae, called the foramen, moving into the limbs to provide motor and sensory function. The type of pinched nerve depends on spinal region (i.e. cervical, thoracic, and lumbar) where the pinch occurred. The cervical and lumbar regions provide motion and flexibility for the spine, whereas the thoracic region supports and protects organs along with the ribs. The extra motion in the cervical and lumbar regions make them more prone to pinched nerves.

Cervical Pinched Nerve (Neck)

The cervical spine has seven vertebrae with intervertebral discs between most pairs, which create flexibility and a wide range of motion in the neck. The discs in the cervical spine can wear over time and with increased motion, resulting in a disc herniation or spinal stenosis in the neck, which pinches the nerve. These changes within the cervical spine may lead to a pinched nerve which can cause problems in the arms.

Thoracic Pinched Nerve (Mid Back)

There are 12 thoracic vertebrae that are all separated by intervertebral discs. Unlike the lumbar and cervical spine, the thoracic spine mainly functions in support and structure; because it is minimally involved in movement, the discs in this region are not as thick as those found in the lumbar and cervical regions. Since there is limited motion, the thoracic spine is not a typical site for causes of a pinched nerve, including disc herniation and spinal stenosis.

Lumbar Pinched Nerve (Lower Back)

The lumbar spine contains five vertebrae, each separated by an intervertebral disc. Like the cervical region, the lumbar region has a higher level of flexibility and a large range of motion. It also bears most of the weight of the body, so it is subject to pinched nerves from the wear of weight bearing, aging, and repetitive motions. Spinal elements such as the discs and joints begin to wear over time which may lead to compression of nerves that branch to the lower extremities, from disc herniations and spinal stenosis.

CAUSES

A pinched nerve refers to compression of a nerve from a causes, such as disc herniation and spinal stenosis. All three regions of the spine (i.e. cervical, thoracic, and lumbar) are susceptible to pinched nerves, but the cervical and lumbar regions are more prone due to their higher range of motion and the burden of weight bearing in the latter. The motion and weight bearing increase stress on structures in the spine, such as facet joints and shock absorbing discs, which can lead to pinched nerves.

Aging

Aging and related arthritis is the primary cause of pinched nerves. Intervertebral discs contain a lot of water and stress from the aging process causes them to dry out, degenerate, and shrink. As discs shrink in size, the space between vertebral bodies and the foramen, the space through which nerves exit the spinal cord, narrows. In addition, the ligaments and facet joints on the spinal vertebrae increase in size with arthritis which may place pressure on spinal nerves. Arthritis may also cause the formation of bone spurs, or bony growths, at the facet joints. Often, more than one type of arthritic change is contributing to the symptoms of a pinched nerve.

Weight

Weight is another common cause of disc herniations because the spine, particularly the lumbar region, supports most of your body weight. As weight increases beyond a healthy level, the vertebral bodies struggle under the increased pressure and this is transferred to the discs. The pressure squeezes the discs, which results in the development of annulus tears and nucleus pulposus leaks. Weight and obesity can lead to recurring herniations at the same disc.

Disc Herniation

Disc herniation may also lead to a pinched nerve. Intervertebral discs are formed from two elements: an outer fibrous area and an inner jelly-like area. The outer fibrous portion may weaken or develop small tears with aging, trauma, and weight gain, potentially allowing the inner jelly-like substance to herniate or slip through. Acute trauma is a large amount of force applied to the spine from a single event, for example, from a blunt hit or a motor vehicle accident. Chronic trauma is repeated stress over time, including forces applied by repetitive tasks at work or with recreational activities. Increase in body weight also adds stress on the spine, weakening the discs, and making them more susceptible to a herniation. As the disc herniates, this pinches the spinal nerve.

Structural Abnormalities

Structural abnormalities of the spine can also lead to pinched nerves. The more common structural abnormalities are scoliosis and spondylolisthesis. Scoliosis is an abnormal curvature in the spine which can accelerate the aging process and arthritic changes, leading to a pinched nerve. Spondylolisthesis is an abnormal alignment of spinal vertebrae, when one vertebrae slides forward or backward relative to the vertebrae directly below. As the facet joints of each vertebra in the spine come together, a space called the foramen is created that allows nerves to branch from the spinal cord into the body. If one vertebra is shifted forward relative to the vertebrae below, this causes an abnormal alignment of the facet joints, narrowing the foramen and leading to a pinched nerve.

SYMPTOMS

The symptoms of pinched nerves range from nonexistent to severe and debilitating. This can depend on the location of the pinched nerve, amount of compression, and cause of the pinched nerve. Pinched nerves occur most frequently in the cervical and lumbar spine due to their range of motion, but more frequently affects the latter.

Cervical Pinched Nerve(Neck)

Spinal nerves that exit in the cervical region are directly involved in the function of the shoulders, arms, and hands, meaning that pinched nerves in this region will create symptoms in those locations. Typically, symptoms from a pinched nerve will only produce unilateral symptoms, symptoms that occur on one side of the body. Symptoms usually manifest as a sharp shooting or throbbing pain, numbness, tingling, or decreased sensation. Pain is experienced in the body part that the pinched nerve is involved in the function of. For example, weakness in the deltoid muscle while raising your arms from your sides could indicate a pinched nerve at the C4-5 level. Other potentially affected muscles include the bicep, triceps, wrist, and hand muscles.

Thoracic Pinched Nerve (Mid Back)

The spinal nerves from the thoracic spine are involved with the function of the chest and abdomen. The exception is with the first thoracic nerve, which is also responsible for the ring and pinky fingers. A pinched nerve at the thoracic levels may cause pain and/or numbness in the back, chest, abdomen, and/or the ring and pinky finger. The nerves from the thoracic spine run directly above each rib. These nerves supply sensation to the torso and motor strength to the intercostal and abdominal muscles. Symptoms of pinched nerves typically unilateral, or only occurring on one side of the body.

Lumbar Pinched Nerve (Lower Back)

Spinal nerves that branch out of the lumbar spine control function in the lower extremities (buttocks, hips, legs, and feet). Therefore, a herniated disc causing nerve compression in this region will produce symptoms in the lower extremities including a sharp, shooting, burning, or electrical pain and potentially numbness or changes in sensation. For example, weakness while straightening the leg could indicate a pinched nerve at the L3-4 level. Other potentially affected muscles include the quadriceps, tibialis anterior, and flexors of the foot. Symptoms may also include neurogenic claudication, a nerve-related pain that increases with walking and improves with rest. These typically occur unilaterally, only on one side of the body, and the specific location of the symptom will vary based on the nerve being compressed.

DIAGNOSIS

Patient history and physical examination are typically the first step in diagnosing pinched nerves. Types of symptoms, duration of symptoms, factors that improve/exacerbate symptoms, treatments that have been already tried, and past relevant medical problems/surgeries are all collected during the history. The physician completes a physical exam to check for specific symptoms by inspecting the back, assessing gait, and testing the upper and lower extremities for motor strength, reflexes, and range of motion.

Both history and physical exam contribute to the diagnosis of a pinched nerve, but imaging is necessary to finalize the diagnosis. X-rays are typically obtained first to look at the overall alignment of the spine and to check for spinal abnormalities such as scoliosis (curve in the spine), that may affect viable treatment options. These 2D results are supplemented with advanced imaging tests such as MRI or CT scans because these show a 3D view of the spine. MRI scans which show soft tissues, such as nerves and discs, are generally preferred over CT scans which show bony elements. Advanced imaging can show exactly which nerve or nerves are being pinched and what is causing the nerve to be pinched. Together history, physical exam, and imaging are all necessary in order to make a correct diagnosis and design an optimal treatment plan for a pinched nerve.

Cervical Pinched Nerve (Neck)

Physical exam results that imply a cervical disc herniation include decreased range of motion in the neck with difficulty moving the chin toward the chest, leaning the head back, or turning left and right as if checking a blind spot while driving. Motor strength testing would be performed on both the upper and lower extremities because weakness in certain muscle groups could imply a disc herniation at the cervical level where the relevant nerve branches off of the spinal cord. For example, weakness in the deltoid muscle while raising your arms from your sides could indicate a disc herniation at the C4-5 level. Increases or decreases in the bicep, brachioradialis, or tricep muscle reflexes are commonly used to test for spinal disc herniation and can potentially identify the affected spinal level because they are connected to the C5, C6, and C7 nerve roots respectively. Other tests include checking for changes in sensation and a heel to toe walk to evaluate balance.

Thoracic Pinched Nerve (Mid Back)

Physical exams checking for a thoracic pinched nerve will be much less involved than those looking for cervical and lumbar pinched nerves. The exam typically begins with examining the back for an abnormal curve, uneven muscles, or skin changes such as bruising. After inspection, the doctor will perform palpations over the muscles and center of the back. The legs would be tested for motor strength to ensure that both legs are at full strength and functioning normally. Lastly the physician may check for changes in sensation from one side of the body to the other.

Lumbar Pinched Nerve (Lower Back)

Physical exam abnormalities for the lumbar spine tend to occur exclusively in the lower body. As with evaluating the cervical and thoracic spine, it is important to start by looking at the back for changes in the skin, decreases in muscle size, or unevenness from one side of the back to the other. The next step would be palpation of the muscles and center of the back. Lumbar spine range of motion is tested with flexion, such as touching toes, and extension, leaning back at the waist to look for decreased motion due to pain. Motor strength testing would be performed on the lower extremities because weakness in certain muscle groups could imply a pinched nerve at the lumbar level where the relevant nerve branches from the spinal cord. For example, a pinched nerve at L3-4 or L4-5 levels may cause weakness with knee extension or straightening the leg. Changes in sensation may also be tested throughout the leg to check for areas with decreased sensation throughout or relative to the opposite leg. Increases or decreases in the patellar and Achilles reflexes are commonly used to test for spinal pinched nerve and can potentially identify the affected spinal level because they are connected to the L3/L4 and S1 nerve roots respectively. Other exam results that imply lumbar pinched nerves are abnormal walking patterns, including inability to walk on the heels and the toes.

CONSERVATIVE TREATMENT

Lifestyle Modification

Certain lifestyle factors may increase the incidence of a pinched nerve, such as smoking and increased weight. Smoking decreases blood flow throughout the body which is needed to repair damaged tissues, including those around a compressed nerve. Cessation may restore blood flow, allowing the tissues to access proper nutrition. Added weight may increase the risk for disc herniation which may pinch the nerve, or the acceleration of the aging process, leading to pinched nerves. Reducing weight through a low-calorie diet and exercise can reduce pressure on the spine, decreasing the symptoms of a pinched nerve.

Repetitive leisure or work-related motions such as excessive bending, lifting, and twisting, along with any activity that may be high impact on the spine, such as running or riding ATVs, can also lead to pinched nerves. Some of these repetitive task activities may be due to leisure and others due to demands of a job. For people with full labor or heavy-duty jobs, you may need to change jobs or support your work with proper lifting technique, relaxed breaks, and equipment such as a back brace to avoid worsening symptoms. You may also need to alter or avoid high impact activities, such as running to reduce the symptoms of a pinched nerve.

Alternative Therapy

Alternative therapies include massages, chiropractic care, and acupuncture. These may also be referred to as manual therapies since they address the spine with hands on technique. Massage relieves tension in muscles surrounding the spine and in arm and leg muscles experiencing radiating symptoms. These muscles may be under tension due abnormalities with walking and changes in posture due to pain from a pinched nerve. Chiropractic care may use specific techniques, such as adjusting the spine or application of traction on the spine. Acupuncture may also provide pain relief as muscles are stimulated electrically.

Physical Therapy/Exercise

Physical therapy focuses on changing body mechanics to improve posture and walking as well as to strengthen and retrain muscles, particularly those in the core. The initial step is meeting with a Physical Therapist for a consultation to assess posture, gait, and muscle weakness and to design a personalized exercise program. Other techniques that physical therapists may use are manual treatments such as massage, ultrasound, and electro-stimulation through a TENS (transcutaneous electrical nerve stimulation) unit. A combination of these methods can provide symptom relief.

A home exercise program may be used in conjunction with or instead of a formal physical therapy regimen. A daily low impact exercise regimen is important for strengthening muscles, especially those in the core. Low impact cardiovascular activities such as walking, swimming, elliptical, and biking are also important for increasing blood flow and strengthening muscles without adding stress on the spine. Home exercise can also lead to weight loss which may reduce pressure on the spine and reduce symptoms. Home exercise routines should be paired with stretches and physician supervision to avoid harm.

Medications

There are multiple types of prescribed and over the counter medications that may be used to treat the symptoms of a pinched nerve. Some of these medications include Tylenol (acetaminophen), NSAIDs (nonsteroidal anti-inflammatory drugs), muscle relaxants, nerve membrane stabilizers, topical medications, and off label medications.

Epidural Steroid Injections

Epidural steroid injections reduce pain by injecting steroid, or anti-inflammatory, medication at a specific level/levels in the spine. As the herniation places pressure on a nerve, this causes inflammation of the nerve and surrounding tissue which causes pain. A specialized needle is used to deliver medication to the correct area, past the muscles of the back and as close to the spinal nerves as possible. As steroids are a natural anti-inflammatory, this may reduce the inflammation around the nerve, diminishing pain caused by the disc herniation. Steroid injections have the ability to provide pain relief for up to several months, and provide better pain relief for radiating symptoms, such as leg pain, than treatments designed for back pain alone. Steroid injections are only safe to have completed 3 times in one year and must be at least one month apart between sequential injections. This is due to the muscle and tendon breakdown with exposure to the steroid medication too often or too soon.

SURGICAL TREATMENT

Cervical  (Neck)

A foraminotomy is a minimally invasive surgical decompression procedure that is performed in the cervical spine to alleviate the compression on a cervical spinal nerve from a pinched nerve. This may be due to bone spur formation or a disc herniation. This procedure is performed through a small midline incision on the back of the neck. A small amount of bone from the back of the vertebrae is removed, called the laminae, so opening for the spinal nerve, the foramen, is reached. The compression is alleviated either by removing disc material or bone spurs that are pinching the nerve. Once the nerve is decompressed, the incision is closed and the procedure is completed.

An ACDF is a minimally invasive surgical stabilization procedure. This is performed through a small incision on the front of the neck. The surgeon tunnels between the thin neck muscles until the spinal column is reached. The old disc is removed and once removed, any contents can be removed around the nerve roots to relieve the pinched nerve. A special implant with bone graft will then be placed in the disc space with screws to secure placement. Once the procedure is completed, the disc level is fused.

A cervical disc replacement is a minimally invasive surgical stabilization procedure that is performed similarly to the ACDF, however the implant is slightly different, as it preserves some motion of the cervical spine instead of creating a fusion in the ACDF. The pinched nerves are alleviated through the removal of the disc material.

Lumbar (and Thoracic)

A microdiscectomy is a minimally invasive surgical decompression procedure that is typically performed on both the thoracic and lumbar spine to address disc herniations, which cause pinched nerves. A small incision is made in the midline of the back until the backside of the vertebrae, laminae, is reached. At this point, a small amount of the laminae is removed until the pinched spinal nerve is well visualized. The compression on the nerve is removed and once completed, the incision is closed.

Endoscopic discectomy is a minimally invasive surgical decompression procedure that uses specialized instrumentation to remove a disc herniation, which is a source or pinched nerves. A small incision is made on the midline of the back and the use of specialized imaging, called a fluoroscope is used. After the incision is made a thin wire, called the guide wire, is placed until it hits bone. A series of small cylindrical tubes are then placed over the guide wire to dilate the tissue and a retractor is placed over the cylinders and the cylinders are removed. A light source is place down the retractor and instruments are placed down through the retractor to remove the disc fragments pushing on the nerve. The retractor is then repositioned, so that the compression can be removed around the nerve on the opposite side of the body. The instruments are removed and the surgery is completed.

A transverse lumbar interbody fusion (TLIF) is a minimally invasive stabilization procedure that uses a specialized implant to fix the appropriate disc level. This procedure is performed through a small incision on the midline of the lumbar spine. Once the spine is reached, the backside portion of the vertebrae is removed, the laminae, until the nerve is reached and the compression on the nerve is removed. The disc material is removed from the disc space and a special implant with bone graft is placed into the disc space with screws placed into the vertebral body above and below the disc space, that are connected via rods. Once the procedure is complete the spinal level is fused.

An extreme lateral lumbar interbody fusion, or XLIF, is a minimally invasive surgery that is performed on the lumbar spine. A small incision is made on the left side, between the hip and the ribs. A thin wire, called a guide wire, is placed and sequentially cylindrical tubes, called dilators are placed through the psoas muscle to reach the left side of the spine. Once the spine is reached, the disc is then completely removed. A special implant is sized, filled with bone graft and placed in the empty disc space. The implant is then screwed in place, with screws placed into the upper and lower vertebral body to provide structure. This will fuse and stabilize the level to prevent any further motion. The XLIF can only be performed on certain levels in the lumbar spine, as the space between the hip and lowest rib is limited, even with specialized positioning of the body on the surgical table.

All procedures used to alleviate the symptoms and structural problems from pinched nerves are minimally invasive decompressive and stabilization procedures. The spinal nerve roots are decompressed properly any mal-aligned vertebral body is stabilized to prevent further motion. Multiple factors are taken into consideration to plan an appropriate surgical option to treat the structural problems associated with a pinched nerve.