Chapter 31 Back pain in the elderly

Case 31.1

1. Using only this information, list the possible causes of Larry’s lower extremity pain. Justify your answer.

Possible diagnosis	Justification
Central spinal stenosis	• General distribution of pain without specific dermatome characteristics • Decreasing pain in squatting position • History of low back problems, sciatica
Circulatory problems	• Feeble pulse bilaterally • Increased pain on walking • Diabetes
Neuralgia due to inflammation/infection/tumour(s)	• Relatively fast development of disability • Numbness and paraesthesia
Polymyalgia rheumatica	• May produce very similar symptoms

2. Why was Larry asked about the relationship of pain to external forces such as position, motion, heat, cold, draft?

To differentiate between mechanical, infectious or circulatory origin of the symptoms.

3. What do you need to examine in this patient?

• Lumbar and pelvic area.

• Circulatory system, especially circulation to lower extremities.

• Nervous system — to look for neurological signs and the distribution of both sensory and motor changes in the lower extremities.

5. Explain the significance of the following signs, in context of your differential diagnosis:

a increasing pain in lower extremities on movement and/or walking

This could indicate either circulatory or neurological problems. In this case, together with the other symptoms, it is most likely due to pressure or irritation on the spinal cord or cauda equina.

b changes in sensory perception in the lower extremities

Indicates functional changes and/or damages to the major nerves of the lower extremities. In this case, it is dermatomal in distribution.

c increased pain and radiation on P-A provocation in the lumbosacral area

Indicates degenerative changes and/or dysfunction of the facet joints and/or degenerative changes or narrowing of the neural canal(s) as well as possible degenerative changes and/or narrowing of the vertebral canal.

6. Larry is referred to a medical practitioner. What investigations are required? Why?

• Magnetic resonance imaging (MRI) of the lumbosacral area for degenerative changes, tumours etc.

• Ultrasound investigation of the circulatory system in the pelvic area and the lower extremities to look for calcifications, deposits and so forth which could interfere with normal blood flow.

• Possible contrast X-ray and/or CT scans of the circulatory system depending on the findings from the other investigations.

Case 31.2

1. Using only this information, list the possible causes of David’s low back pain. Justify your answer.

Possible diagnosis	Justification
DDx 1: abdominal aortic aneurysm (AAA)	Patient’s age, sex, history of smoking, sedentary lifestyle, severity of pain, pale complexion and history of hypertension would indicate a rupture of an AAA. Because the pain had been present in the week preceding presentation and because the patient has not lost consciousness, despite displaying the signs of hypovolaemic shock, it is possible that this is a leak, rather than a rupture
DDx 2: lumbar compression fracture secondary to bony metastases from prostate cancer	Low back pain may be due to metastatic lesions in the lumbar spine resulting in a pathological fracture. This is based on the severity of pain, history of urinary problems, mode on onset and pain not relieved by painkillers
DDx 3: mechanical pain of musculoskeletal origin	Mode of onset, age, previous history of low back pain, achy pain developing to sharp pain as in acute facet sprain
DDx 4: abdominal pathology (eg: appendicitis or gastrointestinal inflammation)	Right groin pain may be from appendicitis, pale complexion may be from systemic condition and low back pain may be referred from gastrointestinal tract
DDx 5: a combination of 3 and 4

2. Why was David asked about:

a whether he has had the pain before

If the patient had experienced the pain before, it would suggest that the cause of the pain is mechanical in origin. If the patient has not had the pain before and cannot relate it to any other type of pain he has experienced, then a more sinister cause should be suspected.

b pain radiating to the legs

Low back pain radiating to the legs suggests a neural impingement. Pain in one leg would be consistent with compression on a nerve root as is found in lumbar radiculopathy, and may be due to either lumbar disc herniation or intervertebral foramina encroachment. Pain into both legs suggests a central disc herniation, compressing the cauda equina.

c the relationship of pain to movement

Pain which is aggravated by movement suggests that the problem is within the musculoskeletal system.

d any relieving factors

Pain which cannot be relieved by changing posture or medication suggests a sinister cause.

3. What do you need to examine in this patient?

The appearance of a person in shock should indicate that the patient’s vital signs must be checked. Further to this, the patient’s description of the pain being something which he has never experienced before, coupled with the risk factors for cardiovascular disease should indicate that an examination of the cardiovascular system is warranted. Thirdly, the patient’s age, cardiovascular risk factors and symptoms of pain in the groin and back, which he has never had before, should direct the practitioner to examine the abdomen with particular emphasis on examination of the aorta.

4. What information can you obtain from these findings? Can you narrow your differential diagnosis?

The physical examination findings increase the likelihood that David has a ruptured AAA which is slowly leaking (a large leak would be associated with a more rapid decline in health) based on the signs of hypotension and the presence of a pulsatile abdominal mass.

5. What is the significance of the following physical examination findings?

a pallor of face, sweating and reduced peripheral pulses

Pallor of face and sweating could be consistent with hypovolaemic shock. Reduced peripheral pulses in the lower limbs may indicate peripheral vascular disease or poor perfusion of the limbs, as may be expected in AAA. A blood pressure of 90/60 is normal for many individuals, and not necessarily considered to be representative of hypovolaemic shock. In a patient who was initially hypertensive, this blood pressure may represent a significant deviation from normal.

b pulse rate 100/min and blood pressure 90/60

With hypotension, increased sympathetic tone causes tachycardia (>100 bpm). During hypovolaemic shock, although the blood pressure may be maintained initially, hypotension develops from loss of circulating blood volume (systolic <100 mm/hg).^[1]

c abdominal tenderness

An expanding AAA will cause some abdominal discomfort, and this can often be localised to either the epigastric region or groin.

d pulsatile abdominal mass

A pulsatile mass located lateral and superior to the umbilicus would suggest the presence of an AAA. It would normally be expected that the pulsation be felt to the left of the midline.

6. Based on the information you have so far, how would you manage David?

David needs immediate emergency referral to the local hospital’s accident and emergency department. An ambulance should be called and David should not be moved until the paramedics arrive to minimise the risk of further rupture and haemorrhage. Rupture of an AAA is responsible for 5800 deaths in men and 3500 deaths in women per year in the UK ^[2] and 0.8% of all deaths per year in the USA.^[3] The mortality rate of AAA rupture is reported to be between 78% and 94% in the USA compared to less than 5% for elective surgical repair of an asymptomatic lesion.^[3]

7. What investigations are required? Why? What would you expect based on the physical examination findings?

Initial screening of a suspected AAA is done by the use of abdominal ultrasound. Although it is recognised that computed tomography (CT) scanning is the definitive means of assessing the size of AAA,^[4] some studies suggest that ultrasound gives a more accurate determination of true maximal AAA diameter.^[4] Scanning is required to assess the size of the aneurysm and also to asses for rupture and blood leaking into the abdominal cavity or retroperitoneal space. In David’s case you would expect to see an enlarged section of aorta, consistent with an aneurysm, and based on the history of abdominal pain and signs of hypovolaemic shock, rupture of the vessel wall.

8. What is your final diagnosis, based on these results? Justify your answer.

Ruptured AAA.

9. Describe the factors which increase the likelihood of developing this condition.

There is some debate in the literature as to what risk factors are specific to the cause of AAAs and at the moment it is possible to say that the exact cause is unknown. It would appear that older age (over 60 years), male gender, smoking and family history of AAA all contribute to an increased risk of developing AAAs.^[3,5,6,7,8] Traditionally, hypercholesterolemia was thought to play a role in the development of AAA through the process of atherosclerosis. Although AAA is not a direct result of atherosclerosis, atherosclerosis does appear to contribute to AAA development.^[8] Interestingly, diabetes appears to have a protective effect against AAA formation. Hypertension, although not a risk factor for the development of AAAs, appears to increase the growth rate of already established AAAs.^[8] Genetic diseases, such as Marfan’s and Ehlers-Danlos syndrome, also increase the risk of developing AAAs.