History of Neck Spinal Stenosis
The history is the patient’s story: how the symptoms began, where the symptoms are located, what is the interference in the quality of life, what relieves and what aggravates. Cervical (neck) spinal stenosis is the narrowing of the spinal canal which reduces the space available for the spinal cord. 
Cervical (neck) spinal stenosis produces symptoms due to spinal cord compression. If the spinal canal in the neck is narrow enough, then the natural motion of the neck may compress the spinal cord. In flexion (bending the neck forward), the spinal cord may be compressed against structures on the floor of the canal (bone spur, disc). In extension, the spinal canal becomes narrower and the spinal cord can be compressed by both the roof structures indenting the spinal cord from behind and driving the cord against the front structures on the floor.
Compression in the neck effects the spinal cord and potentially produces symptoms in the arms, legs and occasionally the bowel and bladder. Compressing the spinal cord is frequently painless. Patients with cord compression that develops slowly may experience numbness in the hands, clumsiness in the hands, shooting numbness down the trunk, arms or legs with neck motion, balance difficulties when walking, an unsteady gait and occasionally disturbance in bowel and bladder function.

Physical Exam of Spinal Stenosis
The physical exam is performed by the doctor to determine the effects of stenosis. An examination of the function of the nerves in the arms and legs may reveal weakness, numbness or reflex change. Abnormal reflex patterns may appear with long standing spinal cord compression. 

Different degrees of spinal cord compression, and how fast it develops determines the physical exam. The patient's physical examination may be normal or extremely abnormal (wheel chair bound as an extreme). 

Diagnostic Studies for Spinal Stenosis
The purpose of diagnostic studies is to answer the question, “where on the electrical diagram is the interruption that explains the patient’s clinical situation.” Diagnostic studies are designed to produce a picture of the interruption (MRI, Myelogram, C.A.T. scan) or to indicate electrical interference of the spinal nerves. (EMG or SSEP). The diagnostic studies must correlate with (explain) the patient’s history and physical exam to be meaningful. Many tests show age related changes that exist in people who do not have pain. (there are people who have spinal stenosis who do not have any symptoms and degenerative changes are common in the spine as patients mature)

TREATMENT OF SPINAL STENOSIS

Natural History
The natural history is the rate that nature cures a particular condition. Nature has been curing things for 3 billion years and a certain percentage of patients with a particular diagnosis are going to be healed by nature. Different patterns of clinical symptoms from cervical (neck) spinal stenosis can be expressed: slow gradual onset of symptoms with a progressive decline in function, sudden change with rapid decline in function and a series of episodes leading to decline during the episodes and then periods with no clinical change until the next episode. 

A point can be reached where the spinal canal narrows so much that there is no space available for the cord. This is critical narrowing. Critical narrowing is a concept of lack of space. After all the spinal cord occupies space and needs sufficient room. The normal spinal cord has a defined oval shape. When compressed from either the floor or the roof or both, the spinal cord shape adapts to the pressure which interrupts the function of the spinal cord and produces symptoms in the extremities.

Conservative Care
The purpose of conservative care is to relieve symptoms and improve function. The critical issue in cervical spinal stenosis with cord compression is the evaluation of the patient's clinical situation (history, physical exam, diagnostic studies) to determine if any conservative care is appropriate or whether surgery is the "conservative option."

Surgery
The goal of surgery is to take pressure off the spinal cord. Different surgical options for cervical spinal stenosis involve anterior (floor) approach, posterior (roof) approach, and sometimes a combined floor and roof approach. Some operations decompress the spinal cord (remove pressure) only, others decompress the spinal cord and stabilize the cervical (neck) spine (fusion, +/- instrumentation). Different approaches, anterior vs. posterior and surgical strategies (decompression and/or stabilization) are employed depending on the patient's particular circumstance. 

Conclusion
Spinal stenosis is narrowing of the spinal canal. The effect of spinal canal narrowing is to reduce the space available for the spinal cord. This reduction in space may lead to spinal cord compression and therefore symptoms in the arms or legs. The impact of stenosis on a particular patient can vary from minimal to severe. The choice of treatment for spinal stenosis involves the patient determining how the symptoms of spinal stenosis effects the patient’s quality of life and balancing two competing risks: the risk of surgery vs. the risk of not having surgery. The strategy of surgery for spinal stenosis is to alter the anatomy to eliminate spinal cord compression.

Spinal Stenosis is narrowing of the spinal canal. The black ring represents the spinal canal and the blue arrows the changes which narrow the canal. The spinal canal has a floor (vertebra, discs), a roof (lamina, ligament), and side walls (facets, pedicles). Stenosis is represented by the remaining space in the center of the black ring bounded by the blue arrows.



Schematic representation of the spinal canal (blue triangle): note the position of the spinal cord (green circles) in the triangle. The spinal canal (blue triangle) can be effected by changes on its borders (black circle, yellow arrows, red facet joints). This drawing represents one ring.

The spine is a series of these connected rings. A single ring may be narrowed or multiple rings may be narrowed. So stenosis (narrowing of the ring) may exist at one ring level or multiple ring levels. Why does narrowing of the ring or rings matter? Inside the rings runs the spinal cord.

External objects can compress the spinal cord changing the shape and interrupting the spinal cord's normal function.



External pressure from anatomic structures can narrow the spinal canal to the point where spinal cord compression occurs.

The spinal cord exists in the space bounded by the ring. Narrowing leads to spinal cord pressure and change in spinal cord shape. This compression effects the function of the spinal cord.

The spinal cord carries messages from the brain to the arms, legs and bladder. But this is a two way street with messages carried back to the brain from the arms, legs and bladder. Arm movements, arm feelings, leg movements, leg feelings, bladder control are the result of the movement of these messages in the spinal cord. Any change in the ability of the spinal cord to carry messages can produce changes in the functions of the arms, legs, or bladder. Spinal Cord Injury can produce total lack of function (paralysis) or partial lack of function (arm weakness, arm numbness, clumsy hands, urinary problems, leg numbness, leg weakness, walking difficulty.



The spinal cord extends from the junction of the neck and the head to the upper lower back. The spinal cord exists between the red lines on this drawing. The outflow to the arms and legs and bladder are represented by the gray arrows. The cervical nerves flow to the arms, the thoracic nerves are sensory nerves across the chest and trunk and the lumbar-sacral nerves flow to the legs and bladder area. Depending on the level (cervical, thoracic, end of spinal cord in upper lumbar area), where the spinal cord is compressed, different symptoms occur. Below the red line in the lumbar area, nerves run from the tip of the spinal cord to the legs and bladder. (it looks like a horse's tail and is called the Cauda Equina). 31 pairs of spinal nerves: 8 cervical nerves, 12 thoracic nerves, 5 lumbar nerves, 5 sacral nerves, one coccygeal pair originating in the spinal cord.



The spinal cord's shape is oval. The area outside the red zone is white substance of the spinal cord: nerve fibers, blood vessels, and support structures. The gray substance: nerve cells, nerve fibers, connecting tissue and blood vessels. The diagram above represents this concept. The diagram below shows the structural organization.

Because this is a cross section, injury to this level of the spinal cord would effect everything below it. The neurons (nerve cells) and the axons (nerve fibers) are critical to the message system of the spinal cord. Injury to these structures can produce profound symptoms.



The spinal cord information system is similar to a telephone cable: message are carried up and down the spinal cord, just like a phone call goes out and a phone call comes in . Messages going along these telephone lines to the brain from the extremities are called efferent. Messages going along these telephone lines from the brain to the extremities are called afferent. The gray zone in the middle is a routing station: messages may cross from one side to the other side, while either climbing to the brain from the extremities or descending to the extremities from the brain.

The normal spinal cord is represented on the right as a cross section. Injury to different regions of the spinal cord can produce predictable patterns since the information pathways of the spinal cord are organized and constant in position in the cord. Injuries to the spinal cord are sometimes subtle producing vague symptoms or grotesque producing a severe disruption in normal function or complete loss of function (paralysis). The diagrams below are used to show injuries to different regions of the cross section of the spinal cord.



Paralysis! Complete disruption of the spinal cord on this cross section. Depending on the location of the cross section in the spinal cord (cervical, thoracic, upper lumbar), determines what functions are lost. Injury to the cervical spinal cord may effect the movement of the arms and hands, as well as the inability to walk. Injury to the lower thoracic spinal cord spares the hands but would effect the ability to walk.



Injury to the anterior 2/3 of the spinal cord results in the loss of movement and sensation below the level of injury. (cervical spinal cord, thoracic spinal cord, upper lumbar spinal cord). Deep sensation may be present because it's messages are carried by the region in the back of the spinal cord which has not been injured. Vibration and joint position senses are preserved.



If half of the spinal cord is injured (front to back) then movement is lost on the same side but sensation (pain, temperature, and light touch) is lost on the opposite side of the body. The sensation messaging system crosses over while the movement messages stay on the same side of the spinal cord until reaching the area of the base of the brain.

The central part of the spinal cord can be injured. Because of the arrangement of the messaging system, a central cord injury in the neck effects the arms more than the legs.



Vibration and joint position sense are lost with injuries to the back of the spinal cord.

The conus is the end of the spinal cord and the cauda equina are the nerves originating out of the end of the spinal cord. Injury to these regions can effect the bladder and legs.

The normal neck. The spinal cord sits in a triangle of space. The floor consists of the disc and uncinate processes which are natural bony projections towards the spinal canal. The facet joints are roof structures as are the lamina.



The space available in the spinal canal in the neck is shown by the arrow. This is the space that comfortably houses the spinal cord. If this distance is too small, then pressure on the spinal cord can exist. Notice that anything on the sides of the triangle could narrow the canal.



Disc or bone spur can project into the triangle and put pressure on the spinal cord. This anterior or floor pressure is due to soft disc herniation or bone spur (osteophyte). 



The uncinate processes (natural bony projections on the floor of the spine) can enlarge with wear and tear (bones remodel along lines of mechanical stress). These processes can enlarge to the point they put pressure directly on the spinal cord, the nerve roots or both.



The canal can be narrowed due to enlargement of the facet joints (red) and/or thickening of the ligament or lamina. These are structures of the roof of the spinal canal and can put pressure from above the spinal cord and compress it against the floor.



The canal can be narrowed due to enlargement of the lamina (blue) and/or thickening of the ligament (yellow) as well as disc, or osteophyte (black) from the floor. Essentially, the spinal cord can be sandwiched between a roof and floor in which there is no room it.



The spinal canal is outlined in blue and the spinal cord outlined in red. These diagrams show the potential effects of neck motion on the spinal cord. With neck flexion (bending the neck forward). the spinal cord could be draped over a disc or bone spur on the floor of the spinal canal. With the neck extended, the spinal cord can be compressed from behind from ligament or bone spur.