'5I Postgrad Med J: first published as 10.1136/pgmj.23.257.151 on 1 March 1947. Downloaded from SCIATIC PAIN * By H. LOVELL HOFFMAN, M.D., M.R.C.P. Honorary Assistant Physician to the Royal United Hospital, and the Royal National Hospital for Rheumatic Diseases, Bath There is no need for me to stress the chaotic operations, and its removal has relieved the state of our ideas in the past regarding sciatic symptoms. We also know that sciatica was pain. The fault lies undoubtedlv with those just as common before the discovery.of this who, from the depths of their armchairs, pro- condition, and that patients recovered without pounded theories based on inadequate operation. The inference to be drawn from pathological evidence, or succumbed to the this fact is that healing or reduction of the almost overwhelming temptation to adopt a lesion may in some cases occur without sur- simple explanation for all cases. To the latter gical intervention. Walshe has tritely replied in discussing this These are the causes of sciatic pain of which particular subject, ' Nature is not interested in we have no doubt. We must now consider simplicity.' other possible causes based on less certain Being faced with the task of producing for pathological grounds. you some order out of this chaos, it is my aim to steer a course midway between the Scylla of Less Certain Causes of Sciatica Protected by copyright. dogmatism and the Charybdis of sheer vague- ness. With regard to sciatic pain we need Sciatic neuritis or interstitial neuritis facts, and first I propose to mention briefly I have already mentioned that this may occur those which are incontravertible. when due to diabetes, alcohol, or arsenic. We know also that interstitial, neuritis of other nerves is not uncommon, ahd examples such as Proved Causes of Sciatica occipital or supra-orbital neuritis, and brachial It is quite definite that sciatic pain may arise neuritis may be mentioned. These con- when the nerve or its central connections are ditions may arise, like other rheumatic mani- affected by a pathological process such as festations, after exposure to damp or cold, and herpes zoster, tabes, new growth or the be part of what we have termed a local or neuritis of diabetes, alcohol or arsenic; dis- general ' fibrositis,' although the pathological http://pmj.bmj.com/ seminated sclerosis is 'a very rare cause. It basis of this lesion is a rather vague one. may also be due to disease in the vicinity of the Although I feel sure that a true brachial nerve's course or central connections., and the neuritis or neuralgia of this nature does exist, following conditions may be cited as examples. many cases of pain in the arm with definite In the meninges, arachnoiditis, syphilis or root signs, have recently been proved to be meningioma. In the vertebral bodies, caries, caused by a cervical disc lesion, which need not osteomyelitis, Paget's disease and new growth. necessarily cause signs of cord compression. on September 26, 2021 by guest. In the pelvis, inflammation or new growth Our ideas regarding the symptom are there- either in the bones or viscera, or inflammatory fore falling more into line with our conception changes in the sacro-iliac joint. of sciatica. Spurling and Scoville (I944); It is also certain that sciatic pain may be Elliott and Krerner (I945). produced by herniation of the nucleus pul- It has been argued that an inflamed sciatic posus of a lumbar intervertebral disc. The nerve has rarely been seen and examined; lesion has now been verified at countless naturally there are few opportunities for this. * A PQstgraduate lecture delivered at the Royal National Hospital for Rheumatic Diseases, August, 1946. £52 POST-GRADUATE MEDICAL JOURNAL March, J947 Postgrad Med J: first published as 10.1136/pgmj.23.257.151 on 1 March 1947. Downloaded from -1- -2- -3- One case was described by Denny Brown found in the upper gluteal regior of cases with (I933) in a woman who died after oxygen had undoubted disc lesions, and I have confirmed been therapeutically injected into the thigh. this observatiop on several occasions. By The author found exudate under the per- electromyographic study of these spots he has ineurium of the individual nierve fibres, but found spontaneous motor activity in the certain other changes which he discovered, muscle, and considers that they are due -to in- Protected by copyright. may have been due to the oxygen injection. voluntary spasm of small groups of muscle More recently Holmes and Sworn (I946) fibres, caused by irritation of the nerve root hiave found evidence of what was termed more centrally. He repeated Kellgren's experi- 'radiculitis ' at operation. 'I his consisted ment and in some cases found continuous either of swelling of a nerve root, or adhesions motor discharge from muscles in the area of around it, for whic4, they were unable to find a .referred pain. He therefore suggests that mechanical cause. localized, spasm can be induced through a The general impression, with which I reflex path which involves the anterior horn personally concur, is that sciatic ' neuritis ' or cells, and that the source of excitation may be rqdiculitis does exist, but is rare. It was res- in, or outside the nerve root. He has recorded ponsible for orly 3 per cent. of a series of cases similar motor activity in the so-called fibrositis z,ollhted by Jacksor in 1943 (vide infra). of the shoulder girdle associated with cervical osteoarthritis, and in the extensor muscles of http://pmj.bmj.com/ Referred sciatica and the role offibrositis the arm in brachial neuritis with or without Kellgren produced pain referred to the root signs. corresponding root distribution by injecting an This work is of great interest and importance irritant substance into the interspinous liga- suggesting a new conception not only of re- ments. It is certain that sciatic pain can be re- ferred pain, but also of that mysterious con- of sacro-iliac as in ' As the it is ferred from disease the joint, dition fibrositis.' regards latter, on September 26, 2021 by guest. early ankylosing spondylitis, or from osteo- fascinating to postulate a vicious circle, arthritis of the hip. Steindler (I940) states that initiated, perhaps, by cold or minor trauma, similar pain !may be referred from areas of producing muscle spasm and pain. By reflex trauma or ' fibrositis ' in the back and gluteal action through the cord, this pain may produce muscles, which are in the territory of the a motor impulse causing further muscle spasm posterior primary divisions of the spinal nerves, in the affected segment, and so on. Such a the anterior primary divisions of which go to reflex process could explain the sudden onset form the sciatic trunk. He further states that of fibrositis, so unlike an inflammation, and our relief is obtained by injecting novocaine into treatment at once becomes rational, breaking these myalgic areas. Elliott (I944), however, the vicious circle at various points. Heat and has pointed out that similar tender areas are immobilization. tend to reduce muscle spasm, March, '947 SCIATIC PAIN 153 Postgrad Med J: first published as 10.1136/pgmj.23.257.151 on 1 March 1947. Downloaded from and nfvQQCaine injvtion relieves pain. Later, Diagno4iF. Number m4spage and manipulation will further free Doubtful ..2 the muscle fibres and encourage them to Fibrositis (local) ..c resume their normal activity. In a recent RuptuLred intervertebral dist. 8 article which, inter alia describes myalgic Areas Hysteria .. .. secondary to visceral disease, Kelly (1946) Fibrositis and neurosis 8 favours a similar hypothesis, and suggests Congenital bony abnormaliti, 4 that.... nervous reflexes are instrumental in Fibrositis (generalized) .. 3 the causation of fibrositic lesions in general.' Sciatic neuritis 3 Malingering 2 It is not my intention to theorize further re- Sacro-iliac strain 2 garding the nature of fibrositis, in the absence Lumbo-sacrao strain 2 of rnore definite pathological proof. It should Spinal osteo-arthritis I.. be remembered that gout, gonorrhoea and Bony infection I focal sepsis may play a part in its causation. Neoplasm of cauda equina The condition has been said to produce Polyradiculitis .. .. .. sciatic pain in two ways, either by reference Secondarv carcinoma .. from remote areas, or by direct spread to the Disseminated sclerosis. I nerve itself. From what has already been Spastic paraplegia (? aetiology) . I stated it seems reasonable to assume that re- ferred sciatica may be so caused, but the con- IOO ception of fibrositis spreading directly to the Sciatica Pain due to Protruded Inter- nerve is more difficult to accept in the light of Protected by copyright. new theories. vertebral Disc The intervertebral disc consists of the The role of lumbar osteoarthritis annulus fibrosus which is weaker posteriorly than anteriorly, a cartillaginous plate above and Harris (I933) and Putti (1927) describe below, and the nucleus pulposus, which lies cases where the nerve roots are compressed at slightly more to the posterior part of the disc. the foramina by arthritis of the intervertebral As a result of trauma and degenerative changes, joints. A spine, however, may bristle with the annulus fibrosus may rupture partially, and osteophytes and yet produce no symptoms; the nucleus pulposus will herniate either in further, in advanced ankylosing spondylitis certain postures only, or permanently. If the sciatic pain is rare. Burt (1933) explained this annulus ruptures completely, the nucleus pro- fact by pointing out that the latter condition is lapses, and part or all of it will come to lie http://pmj.bmj.com/ a sclerosing arthritis, without effusion, which under the posterior longitudinal ligament. rapidly immobilizes the spine. It is probable Owing to the position of the nucleus in the that certain cases of sciatica are due to vertebral posterior part of the disc, and the relative osteoarthritis, especially in older subjects, and weakness of the posterior part of the annulus, that cold, damp and trauma play a part in these protrusions tend to occur posteriorly, the initiating the symptoms; but it is generally nucleus being squeezed like a pea out of a pod agreed that the soft tissue changes of the when the spine is in flexion.