Sciatica is a condition which presents when irritation of the sciatic nerve leads to pain & other various symptoms presenting anywhere between the lower back and the foot. Pain is typically most often experienced in the back of the thigh. Sciatica is a hugely common condition we see in our physiotherapy clinics.
What Is The Function Of The Sciatic Nerve?
The sciatic nerve, the longest nerve in the human body. Originating in the lower part of the lumbar spine, the sciatic nerve runs through the buttock and down the back part of the thigh. Upon reaching the back of the knee, it splits into two smaller nerve branches, which continue to the lower leg and foot.
Like any nerve, the sciatic nerve has distinct functions – to supply specific muscles with strength and power, and to provide sensation to the skin in a specific area. For the strength supply of the sciatic nerve, it directly supplies the muscles at the back of the thigh (upper leg), while indirectly supplying the majority of the muscles of the lower leg and foot via its connections with other nerve branches.
While not having any direct role in providing skin sensation, the sciatic nerve again does do so indirectly in most of the lower leg, again via its connections to other smaller nerve branches.
Sciatica, pain and symptoms caused by irritation of the sciatic nerve, can therefore present in any of the areas supplied by the sciatic nerve, be it directly or indirectly.
What Causes Sciatica?
Sciatica, irritation of the sciatic nerve, can he many causes.
The nerve can very often be irritated in the lower back. This typically occurs with a stiffness or reduction of joint space where the nerve root exits the spinal column, or if a disc has migrated to an abnormal position over time.
A second possible site for sciatic nerve irritation is via the Piriformis muscle, which sits deep to the gluteal muscles in the buttock. With the sciatic nerve running either beneath or actually through the Piriformis, any spasm or tightness of this muscle can compress on the nerve, thereby causing irritation. This is often referred to as “Piriformis Syndrome”, with the Piriformis muscle typically tending to spasm secondary to injury, or localised pain or weakness of the lower back or hip.
A third, less common, site for Sciatic nerve irritation is the Fibular head, a bony feature at the top of the outside aspect of the shin. Stiffening of the joint of which this one forms one part, can irritate the nerve as it wraps around the bone.
Generalised nerve tissue inextensibility, or a general lack of freedom of movement, can also be influenced by lifestyle and postural factors. In this case, no one specific area of the nerve is irritated, but more widespread irritation presents.
What Are The Risk Factors For Sciatica?
- Age – as we age, natural degeneration of bones and discs in the spine can increase the likelihood of irritation of nerve tissue. Sciatica tends to be most common in those aged 50-60.
- Height – this may be a risk factor, especially in men aged over 50.
- Occupation – physically working in awkward or static positions (carpentry, machine operators) has been shown to increase ones risk to sciatica more than simply being in static positions for prolonged periods (eg. sitting at a desk).
- Driving – The his has been shown to be a major risk factor, believed to be due t the combination of compression, immobility, & vibration.
- Smoking? – there is minimal evidence to suggest that smoking can predispose to sciatica.
How Does Sciatica Present?
Several typical factors are reported by those experiencing sciatica;
- Pain presenting anywhere between the lower back and foot often most concentrated on the back of the thigh.
- Sensations of burning or heat are common in patients suffering from sciatica, as are reports of tightness or pulling in a very distinct line.
- Sensations of pins & needles, tingling, and/or numbness are also possible with sciatica, again resenting anywhere between the lower back and foot.
- Discomfort when seated is common, as the weight is placed on the possibly-implicate Piriformis muscle or nerve itself.
- Pain on extending the leg when using the pedals to drive, as this places an increased tension on the injured nerve.
How Can Physiotherapy Help?
Many physiotherapy treatments have been shown to be successful in their treatment of sciatica. Treatment is tailored to suit the individual symptom presentation of the patient, following a thorough initial assessment. Treatment may include
- Exercise-based rehabilitation (strengthening, stretching, movement control)
- Deep tissue release
- Lumbar joint mobilisation
- Nerve “sliding” exercises
- Advice on activity modification
What Can I Do To Help This Condition Myself?
Prior to, or while attending physio, the patient can also help the recovery process by following several steps to address both cause and symptoms of the sore foot
- Regularly change position throughout the day, to maintain optimal nerve circulation and maintain nerve mobility, and prevent lower back stiffening.
- Apply heat (hot water bottle wrapped in a tea towel) to the buttock (if involved).
- Take the foot of the involved leg off the pedal when driving as often as possible (to bend the knee), thereby taking the leg out of its position of maximal tension.