Sciatica
Sciatica is commonly referred to as pain that affects the low back, hips, buttocks, and backs of the legs due to compression and irritation of the sciatic nerve. An injury or impingement of the sciatic nerve can lead to a neuritis (inflammation of the nerve), neuralgia (pain along the course of the nerve), or a radiculopathy (nerve root involvement). Although sciatica can sometimes be the result of a herniated disc, there are other causes and contributing factors that can cause or mimic symptoms of sciatica. Such factors may include postural deviations, piriformis entrapment, and trigger points in the gluteal muscles, all of which are fairly common causes of sciatic pain.
The sciatic nerve is considered the largest nerve in the human body. Segments of the nerve are formed between L4 & S3 in the sacral plexus. The nerve, which is actually comprised of two divisions — the peroneal and tibial, travels through the greater sciatic foramen of the pelvis, under the piriformis muscle, and down the back of the leg to the foot. The peroneal branch and the tibial branch travel down the back of the thigh together until they reach the back of the knee. At this point, the peroneal branch splits from the tibial branch and travels down the back of the lower leg, around the inner ankle to the bottom of the foot. The tibial branch, once at the back of the knee, will wrap around the fibula bone and bifurcate once again into two other branches – the deep peroneal nerve (DPN) and the superficial peroneal nerve (SPN). The DPN travels down the front of the lower leg between the shin muscles and the tibia to the top of the foot. The SPN will travel down the lateral or outside part of the lower leg.
With the exception of the front and inner parts of the thigh, the sciatic nerve innervates all the other muscles of the leg. This includes the hamstrings and all the lower leg and foot muscles. The femoral nerve operates the hip flexors, namely the quadriceps, and the obturator nerve controls the adductor muscles. Due to the sciatic nerve’s origin and wide distribution, it can cause pain and discomfort in the low back, sacro-iliac joint, buttock, hip, back of the leg, and foot.
Signs & Symptoms:
Symptoms may be insidious or have a sudden onset
Unilateral in presentation
Radiating pain that can extend from the low back and buttock area, down the back of the leg, and into the foot
Paresthesias (i.e. burning, pins and needles, numbness), weakness, and muscle spasms anywhere along the course of the nerve
Pain can be a constant, dull ache or a shooting pain down the back of the leg
Pain may increase while sitting and diminish while standing or lying down
Coughing or laughing may exacerbate the pain
Standing in antalgic position: Depending on the site of the irritation, a person suffering from sciatic pain may hunch over and to the side to help alleviate pressure on the nerve
Causes:
A disk lesion, such as a protrusion or herniation at L4-L5 or L5-S1. The disk pushes into the nerve root and sacral plexus causing a radiculopathy
Stenosis: a narrowing of the vertebral canal in which the nerve passes through
Postural deviations: An anterior pelvic tilt, such as one that occurs during pregnancy, can decrease the space in the sciatic notch through which the nerve passes through. A posterior pelvic tilt can shorten the muscles the sciatic nerve must travel under
Piriformis syndrome: When this hip muscle shortens and begins to spasm, it can put direct pressure over the nerve
Sitting for extended periods of time with an object in your rear pocket, such as a wallet, can put direct pressure on the nerve. This is known as “back pocket sciatica”
Trigger points in one of the gluteal muscles can mimic sciatic pain
Joint dysfunction of the lumbo-sacral area
Inflammation of the nerve due to an infection or tumor
Another predisposing factor in the development of sciatica is the course the nerve takes once it exits out of the greater sciatic foramen in the pelvis. This congenital variance may explain why some people are more susceptible to developing sciatica than others.
In a majority of the population, the two branches of the sciatic nerve will exit out of the pelvis, through the greater sciatic foramen, and under the piriformis. This is true in about 85% of people. In approximately 10% of the population, one branch of the nerve passes through the piriformis, and the other underneath. In yet another small percentage, approximately 3%, one branch passes over the piriformis, and the other underneath. And finally, in less than 1% of people, both branches pass through the piriformis.
If the sciatica is a result of piriformis involvement or trigger points in the gluteal muscles, the pain may be more conscribed and only reach as far down as the knee. In a vertebral impingement the pain may be more widespread, radiating into the back and all the way down to the foot in severe cases.
Diagnosis:
A history of unilateral low back pain that extends down the back of the leg is usually the defining symptom. A CT scan or MRI may show a disc herniation in the lumbar spine if one is present. The straight leg raise test, also known as Lasegue’s Sign, can be performed to determine the origin of the pain. On occasion, the pain may be due to a glute or hamstring strain. Other times, the pain may be due to some pathology of the lumbar spine or sacroiliac joint. While lying flat on your back, one leg is passively raised until the pain is elicited. Sciatic pain usually presents itself between 35 – 70 degrees of hip flexion.
Treatments:
If the sciatica is a result of a disk herniation, infection, or tumor, you should consult a doctor as to the appropriate form of treatment.
Mild cases of sciatica will often resolve themselves over time. Ice and heat applications are a great way of addressing the inflammation and muscle spasms associated with sciatica.
Anti-inflammatories and muscle relaxants may be prescribed by your doctor to help manage the pain. And if the pain is particularly acute, steroid injections may provide relief for a period of time.
Women who develop sciatica during pregnancy as a result of an excessive anterior pelvic tilt, will find that their symptoms abate once they deliver and the pelvis returns to normal.
Those suffering from sciatica resulting from obesity or faulty postures, will find that losing the extra weight and strengthening key muscle groups in the low back and abdominals will help correct pelvic imbalances.
Sciatica caused from prolonged periods of sitting and/or back pocket sciatica is easily addressed and typically of short duration.
Those with piriformis syndrome and/or trigger points in the glute muscles can greatly benefit from direct massage to the muscles of the low back and hips. Trigger points in the piriformis can shorten and irritate this key muscle. These changes can cause the piriformis to place direct pressure over the sciatica nerve, which runs underneath it. Trigger points found in other gluteal muscles can often mimic sciatic pain. And although these muscles may not be directly over the sciatic nerve, their pain pattern is very similar to that of an entrapment – such as the one created by the piriformis. Targeted stretches in combination with massage will help to restore extensibility and length to these muscles and help alleviate the pressure over the nerve.
