Lower Back Pain
Low back pain (LBP) describes the pain in the low back region, over the lumbar spines from the first lumbar vertebrae to the first sacral vertebra.
Low back pain (LBP) describes the pain in the low back region, over the lumbar spines from the first lumbar vertebrae to the first sacral vertebra. It is an extremely common problem with up to 80% of people will experience LBP at some time in their life. It is important to understand that this term is only an anatomical description, not a diagnosis.
Symptoms and signs:
Patients may experience the pain that confines to the low back area or pain that radiating down to the legs which is commonly known as sciatica. The pain may become worse with activity, such as working, exercising or doing household work, indicating a mechanical cause of the symptoms. Occasionally, the pain may be worse at night or with prolonged sitting, such as on a long car trip. LBP that comes after walking for a few minutes and relieved by sitting or squatting should raise the possibility of spinal claudication that is commonly found in spinal canal stenosis. In severe cases, patients may complain of numbness or sensation loss or even weakness in the leg if the spinal cord or its exiting nerve is being compressed.
LBP may be due to many different causes. The source of pain may arise from skin, muscles, tendons, ligaments, degenerated joints, nerves, bone and referred pain from internal visceral. Most commonly, LBP is caused by soft tissue sprain or trigger points of muscles from poor posture or faulty biomechanics. Trigger point from Quadratus Lumborum, a large muscle on the two sides of low back is a common pain generator among LBP patients. LBP can be also caused by disc pathologies like annular ligament tear, disc bulges, disc protrusions and disc extrusions. Only 3% of these, however, produce symptoms of nerve impingement. The lumbar facet joint pathologies are reported to be the source of pain in 15–40% of patients with chronic LBP. Refer pain in LBP patients are not uncommon. It can be radicular, caused by stimulation or irritation of the nerve roots or dorsal root ganglion of a spinal nerve. When the pain refers down to the legs, it is commonly called sciatica. The S1 and L5 root are mostly commonly affected. Radicular pain can be caused by pathologies of the spine, like disc herniation or a hypertrophied facet joint, encroaching onto the nerve root, or occasionally, it can be caused by herpes zoster virus infecting the nerve root causing shingles, which is often misdiagnosed as LBP in the pre-eruption phrase.
Another type of refer pain is somatic refer pain which is pain perceived in a region innervated by nerves or branches of nerves other than those that innervate the primary source of pain, and this primary source comes from tissues or structures of the body wall (soma) or limbs. A common example is the lateral buttock pain referred from piriformis trigger points. The other refer pain not to missed is pain coming from internal pathologies like ureteric stone, abdominal aortic aneurysm etc.
Many elderies suffer from chronic LBP which doctors wrongly attribute to osteophytes. However, it involves a complex degenerative process. As people are getting older, the facet joints and the intervertebral discs degenerate and become stiffer. The mobility and stability of the spine will therefore be reduced. If all the joints are not affected equally, which is often the case; the body weight will be shifted onto a few joint causing biomechanical problems. Another group of patients with lower back injuries, or poor posture may have prolonged and excessive stress over the ligaments in the lumbosacral regions. These ligaments are very important as their primary role is to stabilize the lumbosacral spines and maintaining them in correct alignment. With the weakening of these ligaments, those stronger deep and superficial muscles will be recruited to take up part of the workload of the stabilizing ligaments and work too excessively and hence the pain. With time when these muscles eventually become fatigue and weakened, the spine will tend to be further out of alignment and creates a vicious cycle which results in the chronic back pain.
LBP can be classified into acute, subacute and chronic.
80%-90% of patients suffered from acute LBP will recover within 6 weeks.
Only about 5%-10% of patients’ LBP will become a chronic problem, affecting their activities and daily living.
Most acute LBP patients do not require any investigations. However, if they have history of trauma, fever, unexplained weight loss, history of malignancy and history of steroid intakes, X-rays of the lumbosacral spine are indicated to rule out underlying serious pathologies (red flags) such as tumor or fracture. Although CT or MRI can provide more information on soft tissue structures like ligament and muscle tears or pathologies of the intervertebral discs, it is not a recommended routine diagnostic procedure in acute LBP as most of the acute LBP gets better on its own. It's often best to wait and see if the pain gets better with time. Moreover, a lot of studies have confirmed that there was no direct relationship between pathologies found on CT or MRI with the severity of pain. In other words, patients with severe intervertebral disc pathologies on CT or MRI may have minimal or no pain whereas patients with minimal or no pathology demonstrated on CT or MRI can be crippled with severe LBP. Usually, proper history and physical examinations are enough to diagnose and treat most cases of acute LBP. It must be pointed out that even the high resolution 3T MRI may not be good in diagnosing ligaments laxity over the lumbosacral spine and its surrounding regions which are usually the causes of chronic low back pain. Musculoskeletal physicians are however specially trained to diagnose these ligaments laxity. As CT or MRI lumbar spine is good in diagnosing bulging or herniating intervertebral discs, spinal stenosis and nerve compression, it is important to perform this investigation to locate the level of the pathology before decompression surgery.
For patients with low back pain, musculoskeletal physicians will consider the use of medications with proven benefits in conjunction with back care information and self-care. He/she will assess the severity of baseline pain and functional deficits, potential benefits, risks, and relative lack of long-term efficacy and safety data before initiating medications (strong recommendation, moderate-quality evidence)1. For most patients, first-line medication options are acetaminophen or non-steroidal anti-inflammatory drugs (NSAIDs). Opioid analgesics or tramadol are occasionally used judiciously in LBP patients who have severe, disabling pain that is not controlled (or is unlikely to be controlled) with acetaminophen and NSAIDs. For chronic LBP patients, tricyclic antidepressants are an option for pain relief2,3. Antidepressants in the selective serotonin reuptake inhibitor class (SSRI) and trazodone class have not been shown to be effective for low back pain, and antidepressants in the serotonin–norepineprhine reuptake inhibitors class have not yet been evaluated for low back pain1. Gabapentin is associated with only small, short-term benefits in LBP patients with radiculopathy4.
For patients who do not improve with the above options, musculoskeletal physicians will consider the addition of non-pharmacological therapy with proven benefits—for acute low back pain, spinal manipulation5; for chronic or subacute low back pain, a holistic biopsychosocial approach consisting of intensive rehabilitation with physical therapy coupled with psychological, social, or vocational interventions6 , spinal manipulation5, exercise therapy7, acupuncture8, message therapy9 or cognitive-behavioral therapy10 (weak recommendation, moderate-quality evidence)1. Intermittent or continuous pelvic traction has been shown to be ineffective in LBP patients with sciatica11.
For chronic LBP patients who are resistant to all the treatments above, prolotherapy may be useful to control the pain and spinal instability by restoring the strength of the degenerated enthesis or ligaments12. Surgery is needed occasionally to release significant nerve compressions.
腰背痛的原因有很多。因為腰背的皮膚、肉、筋腱、韌帶、神經、退變關節、骼以及內臟的轉移痛均可產生腰背痛，其中軟組織創傷或姿勢不良引發的肌肉激痛點為腰背痛最常見的原因。激痛點病例中，腰方肌 (一組位於腰背兩側粗大肌束) 的激痛點是腰背痛較常見的例子。腰背痛也可由椎間盤病變引起，如纖維環破裂，椎間盤突出或脫出引致神經受壓。據研究報導指出，在所有的腰背痛病人中，只有3%的病例有神經受壓的症狀；慢性腰背痛的病例中，有15-40%是因腰椎小關節病變造成。根性放射痛是因椎間盤脫出或小關節肥大，導致脊神經根或脊神經的背根神經節受壓而引起；若放射痛直達下肢，則為坐骨神經痛。坐骨神經痛多由腰 5 或骶 1 神經根受累造成。除因脊柱病變外，根性痛有時也可由帶狀泡疹病毒感染神經根造成。後者在皮膚出疹之前常被誤診為腰背痛。腰背痛的另一種原因是軀體轉移痛，這種疼痛的特點是感受到疼痛的部位並非產生疼痛的原發點，而原發點存在於體壁或肢體內，梨狀肌激痛點所產生的臀部外側痛便是一例子。還有一種不可忽視的轉移痛是由內臟病變如輸尿管結石、腹主動脈瘤等引起。
大部分腰背痛患者不需要任何實驗室檢查。但是，如果有創傷史、發燒、不明原因消瘦，以及惡性腫瘤史、類固醇服用史，則需進行腰骶椎的X光檢查，以排除潛在的嚴重疾病(紅旗病徵)，如腫瘤或骨折。盡管 CT 或 MRI 可提供很多關於軟組織結構的訊息，例如韌帶和肌肉的撕裂或椎間盤的病變，但仍不建議將其作為急性腰背痛的常規診斷方法。最好是先觀察一段時間以查看病情會否逐漸好轉，因為多數患者會自行好轉。而且，很多研究證實 CT 或 MRI 所發現的病變與疼痛嚴重程度並無直接關系。換言之，當 CT 或 MRI 顯示嚴重椎間盤病變時，患者可能沒有或只有輕微疼痛；反之，患者已有跛行及嚴重腰背痛，卻只有很少甚至沒有 CT 或 MRI 證據。所以大多數急性腰背痛的病例可以通過相關病史和臨床檢查便可作出診斷。但對於椎間盤突出/脫出，椎管狹窄和神經受壓來講，CT 或 MRI 則是較佳的診斷方法。尤其是在手術之前，應做此項檢查以確定病變的位置。
肌骼科醫生會採用已證實有效的藥物、背部保健知識及自我保健相結合的方法醫治腰背痛。開始治療之前，首先會評估病者疼痛和功能障礙的嚴重程度，治療的益處及潛在風險、遠期療效和治療安全性方面的數據（強推薦，中等水準證據）1。大多數情況下，一線藥物是對乙酰氨基酚 (acetaminophen) 或非類固醇類抗炎藥物(NSAIDs)。可待因類 (codeine) 鎮痛劑僅用於嚴重，致殘性的疼痛而一線藥物不能或不太可能控制的病情。對於慢性腰背痛，可選擇三環類抗抑鬱藥(tricyclic antidepressants) 2,3。研究顯示抗抑鬱藥中的選擇性血清素再攝取抑制劑類 (SSRI) 和曲唑酮類 (trazodone) 對腰背痛無效。至於選擇性血清素 - 去甲腎上腺素再攝取抑制劑類 (serotonin–norepineprhine reuptake inhibitors)，則未有腰背痛治療方面的評估1。加巴噴丁 (Gabapentin) 對腰背痛伴神經根病變的病例僅有輕微短期的效用4。
Date: 2 December 2023 (Saturday)
Venue: CUHK Medical Centre