CHAPTER 34 Medical Radiculopathies
Sciatica – This is often associated with rheumatism and gout, but is also frequently brought on by catching cold. Occasionally it is due to accumulations in the bowels, or to diseases of the bones through which the nerve makes its exit. The painful points are usually found back of the trochanter or most projecting point of the thigh bone, at certain spots in the thigh about the knee and ankle joints.
Medicology, a medical text published in 1905.1
HISTORY AND EPIDEMIOLOGY
Sciatica is a constant. It has been present throughout the ages. With humility, it should be noted that it is not sciatica, but the medical theories and treatment that have changed over the years … and not always to the benefit of the patient. Theories of etiology are varied across cultures and time. The equivalent of Medline in the late 1800s was an annual compilation of published research presented by the United States Surgeon General. A search on the term sciatica results in numerous ‘hits’ – articles discussing the presentation and treatment of sciatica as a self-limiting cold ‘settling’ in the back, or flu ‘residing’ in the sciatic nerve. The 1905 general medical text Medicology doesn’t even mention trauma as an etiology.1
Around the turn of the last century the field of physical medicine and rehabilitation was born. A fringe group who espoused electrical treatments of medical problems ranging from cancer to the common cold held their first annual meeting in 1890.2 Though scorned by the medical establishment, this specialty gained popularity with the people, in part due to its apparent success in treating sciatica and back problems.
As medicine advanced, management of back pain became more focused on basic scientific theory than pragmatic outcomes. New theoretical ‘causes’ for back pain and sciatica resulted in alarmingly unchallenged treatments. For example, long before the disc was implicated in sciatica, it was popular to blame sciatica on entrapment of the nerve in the piriformis muscle or on irritation from the sacroiliac joint. In 1928, Yeomans claimed success with surgical treatment of hundreds of people with sciatica and nerve damage that he related to the sacroiliac joint.3 Almost certainly, a number of these people – at least the ones with neurologic deficits – had lumbar disc herniation, a syndrome that would not be discovered for more than a decade. His patients typically recovered and were ‘cured’ in spite of his well-meaning, but wrong, interventions.
Mixter and Barr are rightly credited with proving that sciatica comes from disc herniations.4 But there is history behind this history. In the authors’ first years of practice at the University of Vermont, his senior partner Phillip Davis would often tell the story of Mixter and Barr’s first patient. This Vermonter had excruciating pain down the leg. His small-town doctor told him that it was likely ‘one of those cartilage tumors in the spine’ but that he would get better if he only waited. The disgusted patient ignored his doctor and went for a second opinion at the prestigious Harvard Medical School, where Mixter and Barr performed the first of millions of possibly unnecessary operations, paving their way to fame. More recent literature on the natural history of sciatica show us that, even today, physicians with high-sounding theoretical constructs and a big podium often win out over common sense and clinical insight.
The NHANES survey of American health indicates that about 13% of noninstitutionalized adults have back pain of more than 2 weeks duration, and about 9% of these have sciatica with back pain.5 A lifetime prevalence of 1.5% can be calculated from these studies. But other studies show that up to 40% of people suffer from sciatica in their lifetime.6,7 Regardless of the numbers, from a physician standpoint, sciatica is a very common patient complaint.
DIFFERENTIAL DIAGNOSIS
Jeffrey Saal coined the term ‘pseudo-radicular syndrome’ for the nonspinal disorders that cause sciatica-like pain.8 The causes of pseudo-radicular syndrome can be divided into musculoskeletal causes, focal neuropathies, and neuromuscular diseases.
Among the musculoskeletal causes (Table 34.1), Galm et al.9 have shown that sacroiliac pain occurs in about one-third of persons with disc herniations, and that treatment of the sacroiliac joint in these people results in relief of pain. Trochanteric bursitis is another cause of similar pain that often occurs after onset of sciatica from disc herniation.10 Swezy11 found trochanteric bursitis in 31 of 70 persons referred for evaluation of sciatica or back pain. Most think of hip arthritis in the differential diagnosis of radiculopathy in older persons. In younger persons, avascular necrosis of the femoral head, slipped capital femoral epiphysis, and other unusual hip arthritides can fool the unwary.
| INTRINSIC SPINAL CAUSES |
Paraspinal muscle inadequacy-related to previous surgery,12 deconditioning, stretch of the dorsal root,13 or focal myopathy14,15 is increasingly being reported as a cause of pain.
Focal neuromuscular disorders are not uncommon. Most worrisome are tumors and infections causing compression of the nerves or plexus. Bicknell and Johnson16
