Ⅵ Low Back Pains Diagnosis and Treatment of Lumbar Spinal Canal Stenosis JMAJ 46(10): 439–444, 2003 Katsuro TOMITA Department of Orthopedic Surgery, Kanazawa University Abstract: Lumbar spinal canal stenosis is a syndrome of neurological symptoms that appear due to compression of the cauda equina nerve bundle and nerve roots, as a result of narrowing of the lumbar spinal canal through which the spinal nerve bundle passes, and accompanies the degeneration that occurs with aging. Specific causes related to narrowing and compression are degenerative bulging of an intervertebral disk; thickening of a vertebral arch, an apophyseal joint or the yellow ligament; and spondylolisthesis. All these factors, which are due to various dis- eases, cause narrowing of the spinal canal, resulting in compression of the spinal nerves inside the canal and inducing neurological symptoms. The main symptoms are sciatica and intermittent claudication that are treated with therapies based on the severity of the stenosis. These range from conservative treatment provided at pain clinics etc. and rehabilitation, to surgical treatment. Especially in recent years, lumbar spinal canal stenosis has been treated increasingly in the elderly. Key words: Lumbar spine; Low back pain; Spinal canal stenosis; Intermittent claudication; Sciatica; Nerve root block What is Lumbar Spinal Canal Stenosis? vertebral arch, an apophyseal joint or the yel- low ligament; and spondylolisthesis. Lumbar spinal canal stenosis is a syndrome These factors, due to various diseases, cause of symptoms that appear due to compression of stenosis of the spinal canal, resulting in com- the cauda equina nerve bundle and nerve roots, pression of the spinal nerves inside the canal, as a result of narrowing of the lumbar spinal thus inducing neurological symptoms. Espe- canal, and accompanies the degeneration that cially in recent years, lumbar spinal canal occurs with aging (Figs. 1 to 3). Specific causes stenosis has been treated increasingly in the related to narrowing and compression are bulg- elderly. ing of an intervertebral disk; thickening of a This article is a revised English version of a paper originally published in the Journal of the Japan Medical Association (Vol. 128, No. 12, 2002, pages 1790–1794). The Japanese text is a transcript of a lecture originally aired on September 9, 2002, by the Nihon Shortwave Broadcasting Co., Ltd., in its regular program “Special Course in Medicine”. JMAJ, October 2003—Vol. 46, No. 10 439 K. TOMITA Vertebral body/ intervertebral disk Nerve root Yellow ligament Dural canal Cauda equina Apophyseal joint Fig. 2 Intervertebral disk-level stenosis (nerve root type) Fig. 1 Structure of the lumbar spinal canal The nerve root is compressed by a bone spur generated by deformity of an apophyseal joint. ᕃ ᕆ ᕄ ᕅ Fig. 3 Intervertebral disk-level stenosis (cauda equina type) (1) Deformed and bulging intervertebral disk (2) Bone spur at the apophyseal joint part (3) Thickened yellow ligament (4) Compressed and flattened dural canal and nerve root Table 1 Differentiation of Intermittent Claudication Neurogenic Vascular Nerve root type Cauda equina type Walking Induction of claudication Walking (symptoms reduced with a lordotic position) (symptoms unrelated to posture) Abnormal sensations Character Mainly pain Mainly pain, cold sense such as numbness and cold sense Symptoms Region Mostly unilateral Mostly bilateral Mostly unilateral Paralytic Single-level motor Diversified, such as multi-level / None symptoms perception disturbance motor/perception disturbance Neurological Single-level irritation/ Bilateral Achilles None Physical findings deficiency symptom tendon hyporeflexia findings Arterial pulse Normal Normal Deficient or weakened on dorsal foot Decisive supportive MRC, CT, myelography, MRI, myelography, CT Arteriography diagnostic method radiculography, block 440 JMAJ, October 2003—Vol. 46, No. 10 DIAGNOSIS AND TREATMENT OF LUMBAR SPINAL CANAL STENOSIS R R Fig. 5 A case of nerve root-type intermittent claudication (myelography CT) Left: At the normal level, no stenosis of the dural canal is noted. Right: At the L4/5 level, the dural canal is compressed signifi- cantly on the right side, due to protrusion of an intervertebral disk and thickening of the yellow ligament. Fig. 4 A case of nerve root-type intermittent claudication (simple X-ray) Female, aged 68; a case with nerve root-type intermittent claudication in the right leg. Deformity in the lumbar spine is noted on a simple X-ray image (spur formation, intervertebral space reduction, etc.) ease. (A patient can ride a bicycle for a long time if assuming a lordotic posture.) Sensory march is also noted, whereby abnormal sensa- tion travels from the foot to the buttocks or What Kind of Clinical Symptoms perineal region, or descends from the buttocks Appear? to the lower limbs, with walking. In some cases, bladder and rectal disturbances, such as an The main symptoms of lumbar spinal canal increased urge to urinate, incontinence, and stenosis are chronic, so-called “sciatica” (low penile erection, occur on walking. back pain, leg pain, and feeling of numbness) that occurs on walking, and neurogenic inter- 2. Differentiation of intermittent claudication mittent claudication. These symptoms gradu- Neurogenic intermittent claudication must ally progress over time alternatively deteriorat- be differentiated from vascular intermittent ing and improving. In other words, this disease claudication (arteriosclerosis obliterans and is not accompanied by severe symptoms of Buerger’s disease) (Table 1). Points of differen- nerve irritation or deficiency phenomenon, as tiation are improvement of the symptoms by with disk herniation; or by severe pain at rest, assuming a lordotic posture, findings on palpa- as with metastatic cancer in a vertebra or tion of the plantar arteries, and measurement pyogenic spondylitis. of the upper limb/lower limb blood pressure ratio. Neurogenic intermittent claudication can 1. Neurogenic intermittent claudication be classified into the following three groups Neurogenic intermittent claudication is pain, based on the clinical symptoms and the state of numbness, and weakness in the legs that occur stenosis: and intensify on walking (caused by the load of 1) Nerve root-type intermittent claudication the body weight on the spine), finally resulting is a single-root disorder, and it is characterized in an inability to step forward. Furthermore, by pain and numbness of the same lower limb these symptoms improve by bending forward as the responsible nerve root (Figs. 2, 4, 5). (lordotic position), whereafter the patient can Most cases of lumbar spondylosis belong to this walk again, which is a characteristic of this dis- group. JMAJ, October 2003—Vol. 46, No. 10 441 K. TOMITA Fig. 7 A case of cauda equina-type intermittent claudication (myelography CT) Left: At the normal level, no stenosis of the dural canal is noted. Right: At the L4/5 level, the dural canal is compressed, due to deformity of an apophyseal joint and thickening of the yellow ligament. Fig. 6 A case of cauda equina-type intermittent claudication (myelography) Female, aged 78; a case with cauda equina-type intermittent claudication. Deformity in the lumbar spine (spur formation, intervertebral space reduction, etc.) is noted. rest. Even if the reflex is noted at rest, Achilles Severe stenosis is noted at L4/5 on a myelogram. tendon reflexes disappear bilaterally in a load test. What Should Be Observed by 2) In cauda equina-type intermittent claudi- Which Test? cation, the entire cauda equina becomes con- stricted, resulting in a multi-root disorder with 1. Image test numbness of both legs as the chief complaint (1) Simple X-ray examination (Figs. 3, 6, 7). This disease is often accompanied On the simple X-ray examination (front and by perineal perception disturbance, and/or lateral views), observation should be made of bladder and rectal disturbances — and the the alignment of the lumbar spine and destruc- absence of pain is characteristic. tive changes (hypertrophic changes of the ver- 3) Mixed-type intermittent claudication has tebral arches and apophyseal joints, spur for- a clinical picture including both the nerve root mation of the posterior margin of the vertebral and the cauda equina types. body, narrowing of the intervertebral spaces, shortening of the interpediculate distance, nar- Objective Findings rowing of the intervertebral formen, etc.). (2) MRI examination Generally, there are few objective findings On MRI examination with T1-weighted compared with the subjective symptoms. In the images the condition of the yellow ligament nerve root-type disorder, nerve root irritation and peridural fat tissues are observed, and with symptoms and nerve deficiency symptoms, T2-enhanced images, the range and degree such as perception disturbances, weakened of compression of the dural canal can be muscle strength, and decreased lower limb observed, because the cerebral spinal fluid deep tendon reflexes, are noted, as with shows a high intensity. However, bony tissues herniation of a lumbar disk, which can be help- show low intensity, so CT is superior for obser- ful in diagnosing the segment. vation of osseous lesions. In cauda equina-type disorder, the Achilles (3) Myelographic examination tendon reflex is usually lost bilaterally, even at Since myelography is a slightly invasive 442 JMAJ, October 2003—Vol. 46, No. 10 DIAGNOSIS AND TREATMENT OF LUMBAR SPINAL CANAL STENOSIS Table 2 Operative Treatment of Lumbar Spinal Canal Stenosis Decompression