LOWER back pain, like the common cold, is experienced by many individuals. It affects two-thirds of the adult population at some stage or other. Back pain with sciatica is a common pain syndrome. A herniated, slipped, or prolapsed disc causes this syndrome. This article is based on a physical therapy approach. Intervertebral disc prolapse (IVDP) is common in the neck (cervical) and lower back (lumbar) regions. The onset may be sudden or insidious in nature. In the lumbar spine, the most common sites for disc herniation or lesion are the `L3', `L4' and `L4-L5' segments. The lumbar spine is a mobile structure fixed on the sacral spine. Sacral spine mobility is very minimal when compared to the lumbar spine. When there is a mechanical derangement at the lumbar segments, `L4-L5' are more commonly involved due to this region's greater mobility and narrowed posterior longitudinal ligament support. Bio-mechanical studies of the joint prove that when one segment is deranged, hyper mobility in another segment occurs as a compensatory factor.
Inververtebral discs are located in between two adjacent vertebral bodies. The functions of the disc are:
Sedentary life style — weak abdominal and back musculatures
Pain
The herniated disc may slip either centrally or laterally in the posterior (back) aspect. Another important factor to be considered is that the disc itself is insensitive and most of the disc herniation or displacements are painless, but when they pinch on the sensitive structures in the spinal canal, they cause back pain and leg pain (commonly called as sciatica). The slipped disc contents may irritate the dura mater (outer covering of the spinal cord) in the spinal canal or the nerve roots at the lateral aspect. The dura mater and nerve root sleeves are more sensitive structures. Segmental pain is the referred pain in the leg at particular areas only. For example when the `L4' disc herniates, the pain may be present at the outer side of the lower leg and shin pain and greater toe weakness may be noted. This segmental pain indicates the `L4' segemental involvement in the spine at the lateral aspect. The dura mater irritation may cause generalised back pain with no particular segemental pain, which indicates the disc has slipped in the centre than lateral. This way, we differentiate the slipped disc and the involved irritated segments.
Self-help treatment
Robin McKenzie, a physiotherapist and a world renowned spine specialist from New Zealand and founder of McKenzie Institute, devised assessment and treatment approach for the back pain and referred leg pain. He theorises that leg pain shows the severity of disc herniation and the irritation caused by it on the nerve roots emerging from the spine. This type of pain is called peripheral pain. A patient who complains of lower back pain with no leg pain is said to have centralised pain. The basic principle here is that peripheral pain is more intense pinching of the disc on the sensitive neural structures than the centralised pain.
Treatment should be initiated to reduce irritation to the neural structures in spine and thereby alleviate the leg pain. The best way to alleviate leg pain is by lying flat on the stomach (prone lying) for few minutes, until there is no leg pain (see sketch above). Some may feel more comfortable by placing a pillow down the stomach. It may take four to 40 minutes, depending on the severity of the disc impingement on the nerve root in the spine, but the back pain may be persistent. This back pain may resolve faster when you seek a medical professional's help. Physical therapists trained in spinal manipulation, and spinal joint mobilisation can alleviate the back pain within seven to 12 sessions. It is believed that manipulation may work by moving the disc away from pain sensitive tissue.
Rationale
There is no black magic or witchcraft behind this self-help treatment. Dr. Alf L. Nachemson, a Swedish orthopaedic surgeon and spine specialist concluded in his research that the compression of the disc is greatest when sitting, less when standing and least when lying down. We recommend our patients to avoid sitting as much as possible to decompress the spinal segments or after every 15 minutes of sitting, standing up and arching the back and walking for three minutes which will decompress the spine and reduce the severity of leg pain.
Numbness:
In severe cases of neural impingement, numbness or partial loss of sensation may occur in the leg. This situation does not respond well to self-treatment. Dr. James Cyriax, an English orthopaedic physician and the father of orthopaedic medicine, documented that chronic back and leg pain for more than six months with no improvement may not get better with conservative treatment.
Test
To know the severity of the leg pain, qualitative measurement is done by the straight leg raise (SLR or Lasegues' test), where the patient can lift his leg with the knee straight when lying on the back (supine lying). When there is impingement of the disc in the spinal canal/neural foramen, the leg pain is reproduced or increased during the first 15° to 30° of raise due to the tension created on the sciatic nerve. Any pain reproduced after 50° is due to the tightness of the hamstring (back to the thigh) muscle. This can be used as a standardised test before and after lying down on the stomach to know, whether the decompression has occurred or not. Heating pads can be used to alleviate the back pain as they increase the blood flow to the lower back and provide pain relief only and do not correct the lesion.
Traction
Some patients might have had an experience of using lumbo-sacral traction for 30 minutes a day in the physiotherapy clinic. Few among them would not benefit from traction to alleviate the leg pain and back pain. The reason is that mechanical traction units are effective in nuclear disc lesions, and recurrence of pain after back surgery. The traction is ineffective in annular disc lesions.
Nuclear versus annular lesions
How do we differentiate a nuclear and annular disc lesion? The annular disc lesions are of sudden onset; that is a patient may experience sudden pain down the legs or in the back when attempting to lift heavy objects, riding a motor cycle while hitting a pothole and so on. The annular lesions respond well to spinal manipulation techniques. Nuclear disc lesions are of gradual or insidious onset, the history may be on and off back pain for weeks and back pain getting worse. One fine day the pain radiates down the leg.
Prevention:
The physical therapist may teach the patient stabilisation to strengthen the muscles of the trunk to help prevent a recurrence of the same injury. These exercises can be performed in various positions such as lying on the back, stomach or even lying on a side. Among these exercises, lifting up the opposite arm and leg in a systematic fashion is important to stretch the back muscles. The analogy here is that the spine is a flag pole and the abdominal and back extensor muscles are the flag masts which support the spine.
The physical therapist is the best person to instruct an individual as to when and how these exercises should be performed. Part of the rehabilitation process includes minimising the sitting posture, as this places great pressure on the low back. The patient should try avoiding the use of a motorcycle, scooter, or moped for a few weeks. Two or three-wheelers do not have good shock absorbers and compression of the spine may occur in few minutes when riding these vehicles to work.
When travelling in a bus or train, feel happy when you do not find a seat. Remember that the spine is compressed when sitting down rather than standing. This way, you reach your work place with no pain in the leg and back and have a pleasant day.
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