'Sciatica' remains in usage despite some anachronistic features.Sciatica is defined as pain in the distribution of the sciatic nerve.The term 'sciatica' has been broadly applied to any pain ,including so-called referred, in the distribution of the sciatic nerve.It is believed to arise from ectopic activation of of nociceptive afferent fibres in a spinal nerve /its roots or other neuropathic mechanisms.True 'sciatica' is clearly a form of radicular pain ,and is more properly termed sciatica neuralgia in the common clinical context of a painful lower limbo-sacral radiculopathy.The lifetime incidence is estimated to be 13-49%.The first detailed report of sciatica was transliterated in 1930 by Breasted( Breasted JH .1930.Edwin Smith Surgical Papyrus:University of Chicago) as made in 1550BC.Shakespeare refers to sciatica and Fardon (FardonD. "Biblical pain:Did Jacob have Sciatica?".SpineJ.2002;2(3):228.
The ancient Greeks were familiar with sciatica to describe pains ,or 'ischias' felt around the thigh or hip.Hippocrates referred to 'ischiatic' pain in men 40-60 years of age.The Italian anatomist Contunnnius Dominicus( Domenico Cotugno )(1736-1822) wrote the first text on sciatica in 1764 and for decades 'sciatica' was eponymously called' Cotugno's Disease. He distinguished nervous system 'pain' from the aching pain accompanying lower back pain or lumbago.
The anatomical basis for this pain was still not clear. It was thought to be a primary affliction of the sciatic nerve itself. cases of electricity being applied to the nerve, caustic applications and amputation abound.Fuller(Rheumatism ,Rheumatic Gout and sciatica:The Pathology,Symptoms and Treatment.London:John Churchill;1852),stated that 'the history of sciatica's,it must be confessed, the record of pathological ignorance and therapeutic failure". Stafford and Peng (Br J. Anaesth. (2007)99(4):461-473) opine that many pain management specialists would still agree with such sentiments (in 2007).
The intervertebral disc was first implicated in the early 20th century(Fuller and Peng). Schmorl and Andrae (1929) described small posterior disc protrusions at post mortem but did not associate them with sciatica and felt they were probably asymptomatic in life. Eslberg(1931)described removing cartilaginous 'tumours' from the spinal canal with symptom improvement.His theory that these 'tumours' could be prolapsed disc material was initially rejected by the scholars of the time.
Mixter and Barr reviewed the pathology of all excised spine chondromas held in the Harvard Medical School pathology museum:of 16 ,10 were judged to contain disc material. Mixter and Barr were the first to conclude that sciatica and neurological sequelae were due to a protrusion of normal disc material.Six months later, the first patient with a pre-operative diagnosis of 'ruptured intervertebarl disc' was operated on in the Massachusetts General Hospuital( Stafford, Peng and Hill).This was published in the New England Journal of Medicine as the landmark paper,and since then the prolapse IV disc has been irreversibly linked with the pathogenesis of sciatica.Kelly proposed that pressure on a nerve root would cause loss of function rather than pain and sought other mechanisms for the actual sciatica.Lindahl and Rexed found evidence of inflammatory changes in the nerve roots at time of surgery leading to the theory that prolapse of an intervertebral disc ,as proposed by Mixter and Barr, may provoke an inflammatory reaction in the lumbar nerve roots, causing the typical sciatic type pain.
Investigations have advanced as major indices of the substratum for 'true' sciatica or femoralgia. "true' sciatica is pain extending below the knee with +ve lumbar nerve tension signs with features of an appropriate radiculopathy(sensory, motor, reflex, diminution or loss, wasting in the appropriate root distribution).Detailed clinical examination is mandatory,of course.
Investigations include CT, MR, myelography and EMG/Nerve Conduction Study(NCS). In the absence of significant neural compression in an appropriate root ,there is no indication for surgery for sciatica.EMG has a high specificity (low false +ve rate) but as it does not test the pain nerves( small non-myelinated C-fibres) it has low sensitivity.In EMG +ve studies there are signs of denervation with increased insertional activity,+ve sharp waves+/- fibrillation spikes).The 2014 Savage study(Savage NJ,et al.The relationship between history and physical examination findings in patients with sciatica referred for physical therapy.J Orthop Sports Phys Ther .2014) neither patient history nor key examination findings could outperform EMG when the aim was the determination of radiculopathy.Indeed eminent Brisbane Neurologist, Dr John Cameron taught the adage that' electricity never lies'.
All patients must seek and follow the advice of their treating medical practitioner at all times.
Dr Michael Coroneos is a senior Brisbane Neurosurgeon.
Qualifications: CIME MASE FRACS FRCSI FRCS(EDIN)SN FACS FAIM
MB BS(1st Cl HONS) 1980 MNSA MNSQ MAPS
Examiner RACS/ Mortality Examiner RACS (QASM)/Adjunct Assistant Professor
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