My purpose in writing this article is to clarify a condition that is popularly misunderstood by people. Over the years, the exposure to medical conditions people research has increased to the point of simple confusion. (This allows the consumer to not be misunderstood when being examined and treated by their choice of practitioner.)
Merck manual (15th edition) (Pg. 1291 – 1292) states sciatica as “Pain radiating down one or both buttocks and/or legs in the distribution of the sciatic nerve.” I recommend this source as a universal starting point. Usually, patients present with a presentation of their posture that is leaning to the opposite side of pain. Most of the time the pain is localized on one side but the sciatic can be down one or both sides into the buttocks or back of the thigh or into the calves. Pressure from the lower 3 inches of the lumbar spine and hip bones is usually the location of nerve lower irritation. The sciatic nerve is formed of nerves which arise from the lumbar vertebrae L4-5 and L5 to the 1st & 2nd sacral (tailbone) levels. They form together creating the sciatic nerve just below and to each side of the middle of the sacrum and hip bone (ilium). They then form a course deep to the buttocks (gluteal muscles) and course down through the sciatic notch and between the hamstrings. About midway down the back of the thigh the sciatic nerve splits into the peroneal nerve which courses down to the side of the calves. The large portion of the sciatic nerve becomes the tibial nerve which continues down the back of the leg ending at the tip of the big toe. Many factors can influence irritation of any one of these nerves or the nerve roots which they arise from (L4-5 / S1-2). So the irritation of the roots, trunks, divisions and the sciatic, tibial and peroneal nerves can occur from pressure due to some of the following factors. Pressure can come from mechanical or chemical factors to the spinal cord from the intervertebral disks into the canal and the recesses they travel through. Other irritations can be from the chemical contents released from the disk due to traumas to the area of the disk or the passages the nerves travel through the cord exiting past the disk.
The first nerve passage is the central canal. This is the canal the “spinal cord” moves through before it exits the passage known as the “lateral recess”. The disk can bulge and create pressure in the central or lateral recesses. Usually, if there is a frank trauma (acute) the pressure can seek space in either 3 directions. In the case of repeated pressures, disks can tear creating scar tissue and forming fibrosis. Fibrotic scar tissue can form in the disc allowing only some repair to occur. Bone can also form scar tissue (bone spurs) creating osteoarthritis which can continue creating trauma to the nerve passages in the central or lateral canals. (Refer to vertebral model pictures.)
There are other sources of nerve irritation. The path of the sciatic, tibial or peronial nerves involves passages through muscles, joints, and the compartments they run through. A common source of sciatica is the pressure that the piriformis or hamstring muscles can cause due to entrapment. It is similar to the symptoms of “carpal tunnel” in the wrist. This is of compartmental soft tissue origin and is referred to as “compartment syndrome”. Other sources that can cause or add to the sciatica symptoms are joint malpositions due to posture or frank subluxations, “popping a joint out of its proper anatomical motion”. (Refer to pictures of the vertebral column.)
The spinal cord or the exiting peripheral nerves can receive compression from bulging or tearing disks which in turn can cause pressure from the ruptured disk and can leak & spill toxins into the nerve. Injuries can occur either from acute trauma or repeated traumas to the area. In the case of a traumatic disk bulge, symptoms are usually in the first 24 – 72 hours as opposed to chronic repetitive trauma resulting in a tear of scar tissue. Scar tissue can form where the cord or peripheral nerves exit in the form of bone. This is called osteoarthritis. Again, refer to the vertebrae models.
In the next article I will cover diagnosis of symptoms.
Call us to schedule an appointment and we can discuss Sciatica and if you are suffering from this condition.
