Summary of Serious Causes of Back Pain
Examination of a Patient with Back Pain
Although this is a station related to history of back pain, it is quite common to be asked to examine a patient with back pain, either briefly after taking a history or as part of an extended musculoskeletal station. Below is a brief checklist to guide in examination of a patient with back pain within this station.
Figure 41.1 Scars from L2 vertebrectomy to treat a giant cell tumour
Hints and Tips for the Exam
These signify a serious underlying pathology that needs further investigation. If any of these are present, you should really consider imaging (ideally an MRI, but at least a plain X-ray) and bloods including a full blood count, ESR and calcium level.
| ‘Red flags’ for lower back pain |
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Assessing Possible Cauda Equina Syndrome: What Information to Have at Hand When Referring the Patient to Neurosurgery
Making referrals to other specialities and colleagues is increasingly being assessed in OSCEs, and a serious neurosurgical emergency such as cauda equina syndrome would be a perfect case to test this with. Here are the details that you should be ready with when making a referral:
- Age
- Co-morbidities
- Pre-existing back pain
- History of trauma/spinal surgery
- Detailed time course of symptoms
- Results of full lower limb neurological examination
- Can the patient walk?
- Anal tone
- Bilateral perianal sensation to light touch and pinprick
- Is the patient catheterised or passing urine?
- If catheterised, can the patient feel a strong tug of the catheter?
- Post-void/catheter residual bladder volume
- Use of antiplatelet agents/anticoagulants
- Time last ate and drank
- MRI results if available.
Clearing the Cervical Spine
Patients with suspected neck injury will be immobilised at the scene. Before they can be mobilised, their cervical spine has to be cleared. In unconscious patients, more reliance is placed on the radiological investigations. To clinically clear a spine, the patient must have a Glasgow Coma Scale score of 15, not be intoxicated and have no distracting injuries. Patients must have no neurological deficit and no midline bony tenderness. They should be able to rotate their neck. Radiologically, the films must show the C7/T1 junction to be valid. Interpretation of cervical spine films in the trauma patient is covered in the ATLS guidelines and involves checking for correct alignment and soft tissue spaces within normal limits. In unconscious patients, in whom clinical assessment is lost, MRI may be needed to assess the ligaments.
Immobilising the Spinal Patient
To be correctly immobilised, the patient must be placed on a hard spinal board at the scene, with a properly fitting hard collar, blocks and tape. Without all these components, the patient cannot be said to be immobilised. To move these patients for secondary survey and imaging, they must be log-rolled. If there is an unstable spinal injury and immobilisation must continue, the patient should be placed in a Miami J or Philadelphia collar and complete bed rest ensured. Definitive immobilisation is then performed with a halo vest or operative intervention.
Neurogenic Shock Versus Spinal Shock
Neurogenic shock is a cardiovascular consequence of spinal injury and can occur in spinal cord injuries above T6. It refers to disruption of the sympathetic outflow. This leads to bradycardia and hypotension as there is unopposed parasympathetic activity. It can be distinguished from hypovolaemic shock by warm vasodilated peripheries in neurogenic causes, whereas a patient who is bleeding will be peripherally shut down. Neurogenic shock should be managed in a setting where cardiovascular monitoring is available, and pressor drugs and fluids may be required. Note that ATLS guidelines require cardiovascular compromise to be treated as hypovolaemic shock until this is excluded, so never assume that a known spinal injury patient is compromised due to neurogenic shock until bleeding has been absolutely excluded.
Spinal shock is not related to the cardiovascular system. It refers to a flaccid paralysis and areflexia that occurs after spinal injury and can be reversible.
Ankylosing Spondylitis
This is a seronegative multisystem disease. It usually starts as sacroiliac joint stiffness in young men that progresses to involve the whole back. It is usually worse in the morning. The pathological process includes ossification of ligaments leading to a rigid brittle spine that is vulnerable to trauma. Radiologically, an ossified ‘bamboo spine’ is seen, as well as characteristic Andersson lesions of the endplates on MRI where the ligaments insert. Spinal deformity such as kyphoscoliosis can occur. Systemic features of ankylosing spondylitis include aortic disease, apical lung fibrosis, uveitis, psoriasis and gastrointestinal inflammation.
Key Investigations: When in Doubt about the Integrity of Neural Structures, Go for an MRI
The examiner may ask you what investigations you would like to request. Unless there is a specific indication, do not request X-rays as most of the time they will come back as appearing normal or with mild osteoarthritic changes – and they also expose the patient to large volumes of radiation. The investigation of choice to investigate any structural or inflammatory pathology in the back is an MRI scan.
You could justify routine blood tests, for example full blood count, Us+Es, ESR, C-reactive protein and bone profile, as these could indicate a primary or secondary malignancy and inflammatory causes of back pain.
‘Yellow Flags’
‘Yellow flags’ are psychosocial risk factors for developing chronic back pain. These may include the following:
- Problems at work, for example the patient is bullied at work and therefore uses back pain as an excuse to be not working
- Social withdrawal or lack of social integration
- A past or current medical history of depression, stress or anxiety, or mental health problems
- Low self-motivation and failure to actively participate in activities that may help them, for example physiotherapy
Cauda Equina Syndrome
This a neurosurgical emergency due to compression of the nerve roots in the thecal sac below the level of the conus medullaris – untreated, it can lead to paralysis and loss of bladder and bowel control; this has been covered in detail in Chapter 11 on rectal examination. It is one of the most common causes of medicolegal action by patients.
Common Causes of ‘Simple’ Musculoskeletal Back Pain
Back pain could underlie a very serious pathology, but the vast majority of patients suffering from back pain have ‘simple/musculoskeletal’ back pain. Some of the common causes of this are described in the table.
| Type | Comments |
| Mechanical | The most common cause of lower back pain. It is commonly due to age-related disc degeneration or musculoskeletal injury after minor trauma. You may want to suggest a trial of analgesia and physiotherapy |
| Posture | Bending forwards to lift a heavy box or standing all day, for example with a job as a security guard, can lead to back pain. Suggest that the patient reports this problem to the occupational health department where they work |
| Sciatica | Caused by irritation of the sciatic nerve. Patients will describe pain that shoots down their legs and can be severe. Physiotherapy assessment will be helpful, and if the pain does not resolve, MRI can be used to assess nerve root impingement. |
Questions You Could Be Asked
Q. What would you advise a patient with mechanical lower back pain in a GP appointment?
A. It is important that patients do not take to their beds in the belief that movement will damage their back. Encourage them to go about their normal activities at work and at home. A referral for physiotherapy is also useful.
Q. Why is degenerative disc disease less common in the thoracic spine?
A. Degenerative disease and trauma occur at the most mobile segments of the spine, i.e. the cervical spine and thoracolumbar junction. The thoracic spine is relatively immobile and is well supported by the ribs, making it less vulnerable to degeneration and injury.
Q. What is an ASIA chart?
A. This is a standardised method developed by the American Spinal Injury Association to assess motor function, sensory function and anal tone. It classifies spinal cord injury as complete or incomplete, which has prognostic value. Clinically, it is useful to assess neurology serially and detect improvements or deteriorations, even when the tests are carried out by different examiners.
Q. What are some differential diagnoses for back pain?
A. Serious and common pathologies can masquerade as back pain. These include abdominal aortic aneurysm, urinary tract infections and upper tract renal disease, aortic dissection, myocardial infarction, ectopic pregnancy, pancreatitis and other retroperitoneal pathology, and duodenal ulcers.
Q. Which scan is useful in osteoporosis?
A. A DEXA scan.
Q. Which scan is useful for distinguishing between infection and malignancy?
A. Positron-emission tomography.
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