• Routine imaging early on in the course of low back pain is of no benefit [1]. An MRI scan can detect spinal metastases in patients with normal plain X-rays or CT scan [2]. A nuclear bone scan can also detect metastases in the vertebral column before cord compression but MRI is superior [3].

• In most patients with low back pain, symptoms resolve without surgical intervention:

• Physical therapy and non-steroidal anti-inflammatory drugs (NSAIDs) are the cornerstones of non-surgical treatment [4].

• Superficial heat is the only therapy with good evidence of efficacy for treatment of acute low back pain.

• Bed rest is often advocated for the treatment of acute low back pain but continuing ordinary activity may lead to a more rapid recovery [5].

• There is conflicting evidence of efficacy for spinal manipulation in low back pain [6, 7].

• Massage and acupuncture are better than no treatment but have not been compared to conventional treatment.

TREATMENT OF CHRONIC BACK PAIN

Chronic back pain can be very difficult to treat. Although there is limited evidence for the efficacy of aquatic exercises [8], this author¹ has seen numerous patients return to a normal life once they began swimming on a regular basis, at least three times per week and 20 minutes at a time.

Note: A randomised study detected higher ambulation rates in patients with malignant spinal cord compression (MSCC) who received high-dose dexamethasone before radiotherapy (RT) compared with patients who did not receive corticosteroids before RT (81% v 63% at 3 months, respectively; P = 0.046).

¹ Personal observations.

PROBLEMS IN THE UPPER LEG

Painless numbness

MERALGIA PARAESTHETICA

Meralgia paraesthetica is very common, particularly in patients who are overweight. It is essentially about the only cause of numbness in the thigh or upper leg because compression of the sensory nerve roots in the upper lumbar (L2–3) spine is very rare.

Symptoms:

• Symptoms may be intermittent initially, but subsequently the patient may develop permanently altered sensation.

• Symptoms vary from a mildly altered sensation over the anterolateral aspect of the thigh, often only noticed when the patient touches the thigh or clothes brush up against the thigh, to a more marked alteration in sensation with persistent numbness within the distribution of the lateral cutaneous nerve of the thigh but not always involving the entire extent.

• Some patients complain of pain and others may experience dysaesthesia, an unpleasant sensation when the skin is touched. This condition is due to compression of the lateral cutaneous nerve of the thigh beneath the inguinal ligament just medial to the anterior superior iliac spine and pressure over this point is often associated with tenderness.

• The presence of weakness or an altered knee reflex excludes the diagnosis.

• The condition may be unilateral or bilateral.

Examination: The simplest test is to stroke the skin over the lateral aspect of the thigh and, if there is altered sensation, test in all directions, mapping out the exact pattern and sensory loss. The patient is then shown Figure 12.1 and immediately identifies the problem.

FIGURE 12.1 The area of sensation supplied by the lateral cutaneous nerve of the thigh Reproduced from Aids to the Examination of the Peripheral Nervous System. 4th edn, Brain, 2000, WB Saunders, Figure 78. p 50.

Another diagnostic test is to inject local anaesthetic in the region of the lateral cutaneous nerve beneath the inguinal ligament; a transient resolution of symptoms is considered diagnostic [9].

MANAGEMENT of MERALGIA PARAESTHETICA

Once the benign nature of the condition is explained, the great majority of patients do not request any specific treatment. In a number of patients the problem may resolve spontaneously [9]. Patients with pain or dysaesthesia may respond to a corticosteroid injection and, if that fails, decompression of the nerve or avulsion of the nerve (neurectomy) [10]. This latter procedure will replace dysaesthesia with permanent numbness. Regardless of the treatment chosen most patients remain free of symptoms following treatment [9, 11].

Pain and weakness in the upper leg

DIABETIC AMYOTROPHY/FEMORAL AMYOTROPHY/LUMBOSACRAL NEURITIS

The clinical features of lumbosacral neuritis, femoral amyotrophy and diabetic amyotrophy are virtually identical, except for the presence of diabetes.

Symptoms:

• Increasingly severe pain in the buttocks, hips and thighs developing over hours to days is the initial presenting symptom. It is most often unilateral but, as in brachial neuritis, the contralateral side may be involved, usually within 1–2 weeks.

• In addition to the pain, severe weakness and subsequently marked wasting of the quadriceps muscles occurs with or without parasthaesia in the anterior aspect of the thigh and at times the shin. The weakness can be so severe to render the patient unable to walk.

• Sensory symptoms are usually minimal.

• Weight loss is not uncommon [12].

Examination: The examination reveals weakness of hip flexion and knee extension with an absent knee-jerk. Although it may occur at any age, lumbosacral neuritis is more common in the middle-aged to elderly [13].

The aetiology of these conditions is uncertain but it is thought to be based on an inflammatory vasculitis [12, 14].

MANAGEMENT of DIABETIC AMYOTROPHY/FEMORAL AMYOTROPHY/LUMBOSACRAL NEURITIS

Although the condition may resolve spontaneously after many months or years, immunomodulatory therapy, including corticosteroids or even cytotoxic drugs, may shorten the duration of the illness. Intravenous immunoglobulin has also been recommended and several case reports describe apparent dramatic responses [15, 16].

At this point in time there are no randomised controlled trials to guide therapy but, in the absence of specific therapy, significant disability persists for months or years.

POLYMYALGIA RHEUMATICA

Polymyalgia rheumatica is a condition seen in middle-aged to elderly patients.

In both lumbosacral neuritis and polymyalgia rheumatica there is constant pain. The worsening of pain with movement of the hips is seen only in polymyalgia and the presence of severe weakness and sensory disturbance occurs only in lumbosacral neuritis.

Symptoms: It presents with aching and stiffness predominantly affecting the shoulders but in 50–70% of cases may also affect the hips [17]. The condition is thought to relate to synovitis of the proximal joints and extra-articular synovial structures. The pain is constant day and night, as opposed to osteoarthritis of the hips where the pain mainly occurs on weight bearing. It often radiates to the knee and is exacerbated by movement of the hip joints. Although initially it may be unilateral, almost invariably patients develop bilateral symptoms.

A low-grade fever, fatigue and anorexia may occur in as many as 40% of patients and the presence of high spiking fevers should alert the clinician to the possibility of an associated giant-cell arteritis affecting the aorta and major branches. This can result in constant headaches, scalp tenderness and jaw claudication (see Chapter 9, ‘Headache and facial pain’, for further discussion).

Examination: The examination reveals restricted active and passive movement of the hips but in the absence of any joint swelling.

MANAGEMENT of POLYMYALGIA RHEUMATICA

In patients with polymyalgia rheumatica the erythrocyte sedimentation rate is invariably raised and corticosteroids are the treatment of choice. Doses as little as 10–20 mg/day almost invariably lead to a rapid resolution of the aching and stiffness within days and a rapid response at this low dose is considered diagnostic.

Occasional patients may require higher doses for longer periods [17]. If the patient fails to respond to 30 mg of prednisolone within 1 week the diagnosis should be questioned.

Early cessation of steroids may lead to a relapse and treatment at a low dose should be continued for 1–2 years [18]. Methotrexate has been shown in a randomised controlled trial to be an effective steroid-sparing agent.

Unfortunately, side effects of steroids in this group are common.

DRUG-INDUCED MUSCLE PAIN AND/OR WEAKNESS

A large number of pharmaceutical agents, including lipid lowering agents, NSAIDs, antineoplastic drugs and even over-the-counter essential amino acids, such as L-tryptophan, can result in myalgia or even myositis causing muscle pain, cramps, swelling, tenderness and weakness [19, 20]. This list is almost certain to enlarge with the advent of new therapeutic agents.

In any patient presenting with myalgia or muscle weakness a detailed list of drugs used should be obtained and each drug should be checked to see if it has been reported to cause myalgia or myositis. Some drugs produce a pure muscle disorder; others are associated with a neuropathy. The pharmacy department of the public hospital is a very useful resource, as is the patient’s own pharmacist.

Weakness in the upper leg

POLYMYOSITIS/DERMATOMYOSITIS

Inflammatory disorders of muscle, including polymyositis, dermatomyositis and inclusion body myositis, are extremely rare and most general practitioners are unlikely to encounter a case during their working career.

Patients present with the insidious onset of proximal weakness in the legs in the absence of sensory disturbance. The weakness is bilateral but may be asymmetrical. Pain in the muscles occurs in approximately 50% of cases but, as opposed to the above two conditions, is rarely severe. Dysphagia, neck weakness and impaired respiratory function may occur [21]. Inclusion body myositis affects the long flexors of the fingers and, in the lower limbs, the extensor muscles of the knees and hip flexors, resulting in significant proximal weakness. In this latter condition the knee reflex is often absent, whereas in polymyositis and dermatomyositis the reflexes are preserved.

MANAGEMENT of MYOSITIS

Most patients will have an elevated creatinine phosphate kinase (CPK), but a normal CPK does not exclude the diagnosis. The nerve conduction studies (NCS) should be normal, but electromyography may demonstrate a typical myopathic pattern associated with fibrillation potentials and positive sharp waves indicating an inflammatory muscle disorder. Magnetic resonance imaging, contrast-enhanced ultrasound and positron emission tomography can demonstrate abnormalities in muscles in patients with inflammatory myositis and can help determine the site for the definitive diagnostic test, a muscle biopsy [22].

Corticosteroids are the cornerstone of treatment, unfortunately often associated with significant side effects. Other immunomodulatory drugs, such as azathioprine, methotrexate, cyclosporine, cyclophosphamide, interferon, intravenous immunoglobulin and plasma exchange, are often used as steroid-sparing agents despite the lack of good evidence regarding the effectiveness of any of these treatments [23]. Apart from exercise there is no specific treatment for inclusion body myositis at the time of writing this text.

MUSCLE WEAKNESS DUE TO ENDOCRINE DYSFUNCTION

Hyperthyroidism, hypothyroidism and Addison’s disease may all present with muscle weakness. Usually there are associated manifestations to point to the underlying endocrine disorder. Hyperthyroidism may also present with periodic paralysis [24] or rhabdomyolysis [25] and hypothyroidism may present with muscle hypertrophy [26].

The weakness will resolve with correction of the endocrine disturbance.

PERIPHERAL NEUROPATHY

Certain peripheral neuropathies such acute and chronic inflammatory demyelinating peripheral neuropathy and the IgG- and IgA-related peripheral neuropathies can result in significant proximal weakness in the lower limbs. However, this rarely occurs in isolation and these patients usually present with generalised weakness affecting the proximal lower limbs and the distal upper limbs and neck weakness with or without respiratory muscle weakness. Peripheral neuropathy is discussed in more detail later in this chapter.

PROBLEMS IN THE LOWER LEGS AND FEET

Unpleasant sensations in the feet

In the lower leg and feet patients can experience unpleasant sensations at rest that can cause difficulty walking or unpleasant sensation at rest improved by walking or, in fact, that can be improved by walking. Figure 12.2 shows an approach to patients with discomfort or unpleasant sensation in their feet. Erythromelalgia and painful legs moving toes are extremely rare.

FIGURE 12.2 Suggested approach to pain in the feet

There are many non-neurological causes of pain in the feet where pain is either exacerbated or precipitated by weight bearing and/or walking. These include osteoarthritis in the ankle or joints of the feet, a calcaneal spur and plantar fasciitis. The neurological causes of pain in the feet that can result in difficulty walking due to pain include Morton’s neuroma or metatarsalgia and tarsal tunnel syndrome. All will have pain with weight bearing, but there are subtle differences in the nature of the pain and the presence of altered sensation that occurs with the neurological causes to help differentiate the various entities.

UNPLEASANT SENSATIONS AT REST THAT DO NOT CAUSE DIFFICULTY WALKING

Restless legs syndrome (RLS) and burning feet are the two common conditions that cause unpleasant sensations in the feet and lower legs. They do not interfere with walking; in fact, the symptoms improve with walking with RLS and walking on a cold surface with burning feet.

Restless legs syndrome: Restless legs syndrome [27–31] is common, affecting 5% of the population. However, many patients complain that most doctors do not seem to be aware of the entity or know much about it. A more appropriate term is restless limbs syndrome because in more severe cases it can also affect the upper limbs and, rarely, symptoms may be confined to the upper limbs.

The essential features of RLS are:

• Patients develop symptoms when they are not moving, such as prolonged sitting at the dinner table, on an aeroplane or in a lecture or movie.

• Symptoms are particularly severe in bed at night.

• Patients find it very difficult to describe the nature of the symptoms except to say that they are unpleasant.²

• Patients cannot keep their limbs still because of this unpleasant sensation that feels deep inside the limb, not over the surface or affecting just the skin.

• The pain is in the feet, shins, calves and often seems to cross joints but is not confined to the joints.

• Symptoms persist on and off for hours until patients are forced to be up and about.

• Both legs are usually affected although the symptoms can be either confined to or more severe in one leg.

• Patients invariably pace the floor at night to obtain relief but, unlike burning feet syndrome, they do not need to walk on cold surfaces and the symptoms are not relieved by moving the feet to where the sheets are colder.

• There are no symptoms during the day unless the patient sits down.

• Sleep is disturbed whether the patient is sleeping at night or during the day.

• The neurological examination of the affected limbs should be completely normal, although sometimes this condition is associated with a peripheral neuropathy, so patients should be examined specifically looking for absent ankle reflexes, weakness of dorsiflexion of the toes and feet and possible peripheral sensory loss affecting the toes and distal aspect of the feet.

The condition can occur at any age although most patients will have experienced their first symptom before the age of 30. The symptoms are more marked in the presence of renal failure, iron deficiency and pregnancy. It is important to test for iron deficiency and impaired renal function.

The aetiology of RLS is unclear although there is a genetic factor with autosomal dominant and autosomal recessive inheritance. As it is predominantly inherited as an autosomal dominant condition, a positive family history can be obtained in up to 90% of patients with detailed questioning, although the patient may not be aware of the specific name but can recall their parents or grandparents pacing the floor at night. Other patients will initially say that there is no other family member affected but, when sent away to enquire, discover one or more relatives who have the condition. In many but not all patients there is involuntary jerking of the limbs referred to as myoclonus. The symptoms of RLS increase in severity with increasing age and duration of the disease.

Conditions that may be confused with restless leg syndrome include peripheral vascular disease (PVD) and two very rare conditions, akathisia and a curious entity called painful legs and moving toes.

MANAGEMENT of RESTLESS LEGS SYNDROME

Exclude iron deficiency and renal failure.

Abstinence from alcohol, caffeine, nicotine and drugs that may exacerbate the problem is advocated [32].

A number of treatments have been recommended:

• Some patients can minimise their symptoms by either exercising just before retiring to bed or by running several kilometres each day. In most patients such exercise is not practical and drug therapy is necessary [30].

• Levodopa is considered the treatment of choice [30, 33].

• Other medications include benzodiazepines such as clonazepam [34], the dopamine agonists pramipexol [35] and ropinerole [36], rotigotine transdermal patches [37], in severe cases opiates such as oxycodone [38] and in very severe cases methadone [39].

Note: Methadone has not been studied in randomised controlled trials; the evidence is based on a case series.³

³ Personal observations in several patients suffering from very severe restless legs syndrome is that methadone has provided significant benefit, although tachyphylaxis has occurred, requiring increased doses. Methadone is approved for the treatment of severe RLS by the Australian Pharmaceutical Benefits Scheme on an authority preseription.

The characteristic feature of PVD is exercise-induced leg pain relieved by rest but occasionally it can cause pain at rest. The symptoms are confined to the lower limbs and upper limb symptoms would exclude this diagnosis. The pain is usually in the feet and calves; very rarely, buttock pain can occur due to involvement of the internal iliac artery. The peripheral pulses will be difficult to palpate with PVD.

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