Back and related limb neurological problems

Chapter 5 Back and related limb neurological problems



Ming Kon Yii, Andrew Danks, Marinis Pirpiris



5.1 Introduction




Low back pain is a common presenting complaint; however, its diagnosis and management is often perceived as a tedious and frustrating process. This stems from an underlying aetiology that is commonly obscure and a response to treatment that may be disappointing. While no text can substitute for the clinical bedside tutorial, which hones one’s decision-making ability, this chapter will attempt to provide a scaffold on which the generalist can approach the examination of the back that will provide the relevant findings on which conclusions may be based.



History


The aim of history taking and examination relating to any body system is to determine:






The clinician therefore elicits responses to a series of predetermined questions that best elucidate the most likely diagnosis while excluding relevant differential diagnoses. The back is no exception. Experienced clinicians will most often have the ultimate diagnosis prior to embarking on clinical examination and investigations with the latter confirming, rather than determining, the diagnosis. The examination of past and family history may also help confirm one’s suspicions.


Back disorders commonly present with local symptoms of pain and stiffness. However, deformity and referred symptoms of pain, weakness or paraesthesia affecting the limbs are not uncommon. A description of each of these symptoms must be elicited in order to form a reasonable hypothesis as to the underlying pathological process. The nature, site, intensity, distribution and duration of the pain are always a part of any assessment in order to begin formulating a diagnosis.


‘Back pain’ may mean pain anywhere along the spine from the neck to the buttocks. Patients are often vague in their description and as such complaints such as the ‘small of the back’ should be clarified. Radiation of the pain must be elicited because the distribution may guide the clinician to the site of the pathology — pain that radiates to the lateral aspect of the foot is commonly a presenting symptom of compression of the first sacral nerve root (sciatica). Arm pain relating to cervical disc prolapse (brachalgia) may also present with pain radiating to the relevant dermatome.


Stiffness is a rather vague term that may be related to pain, muscle spasm or deformity. It is the pattern of the stiffness may be more enlightening — early morning stiffness may be more in keeping with an inflammatory arthritis, post-activity stiffness to a degenerative process and continuous stiffness to a bony deformity that impedes motion. Acute deformity may lead one to suspect joint instability or fracture that may be related to an acute process, such as trauma, or a chronic process that destabilises the integrity of the skeletal elements, such as infection or tumour. However, acute painful deformity is also seen in degenative cases.


Factors that influence the pain must also be elicited. Any precipitating injury or strain should be inquired after. The sudden onset of back pain after a provocative activity is often an indication of a mechanical basis to the back pain, whereas the sudden onset of back pain with the most minor of trauma may indicate a pathological process, such as a fracture of a vertebra harbouring a metastatic deposit or pain of a non-organic nature. Mechanical back pain (pain originating in anatomical structures when they are loaded) is usually aggravated with weight-bearing activities and relieved during rest. Sneezing and straining may exacerbate pain due to nerve root compression from changes in pressure in the cerebrospinal fluid (CSF) or disc. Changes in urinary or bowel function is a mandatory part of the assessment, as urinary retention with or without overflow incontinence is a symptom that mandates emergent assessment in order to exclude a cauda equina syndrome.


Certain questions must also be asked to gauge the effect of the pain on function such as the effect of the pain on walking, lifting, dressing, washing, toileting and walking up and down stairs. It is also important to know as much about the person as the pain they are experiencing. As such, questions relating to the person’s affect must be asked in a subtle manner so as to avoid offending the person with any perceived implication of dishonesty — the person’s affect may modify their appreciation of organic pain. The clinician must always be aware of non-organic spinal pain such as psychosomatic pain and malingering.


A history of previous treatments is also an important element as this gives a strong indication of the course of the pain and permits an assessment in the case of organic pain as to whether all conservative measures have been exhausted prior to embarking on surgical treatment. Furthermore, the degree of success of previous surgical treatments must also be elicited in order to guide any future management decisions. Conservative measures may include rest, medication, physiotherapy, exercises, weight loss and other miscellaneous treatment modalities such as relaxation therapy and acupuncture.



Examination


By the time the clinician reaches the examination stage, he/she should be confirming suspicions rather than ‘fishing’ for a diagnosis. The examination should be conducted in a predetermined manner. The sitting posture may be observed during the phase of history-taking, while gait will have been observed in a preliminary fashion during the patient’s entry into the room.


The patient is examined undressed to underclothing and barefoot. The clinician then watches the person walk. Gait is first observed from front and behind and then from the side in order to detect abnormalities in both the coronal and sagittal planes. The patient may favour one leg or hold the spine stiff while walking. They may walk with a flexed gait as with lumbar canal stenosis or they may have lost their lumbar lordosis as with the muscle spasm of disc herniation or inflammatory lesions. While it would be ideal to describe transverse plane abnormalities such as intoeing from a ‘bird’s eye view’ this is seldom feasible and commentary is passed on rotational malalignment from the observation made in the frontal plane.


The patient is next examined standing. The posture is assessed with particular attention to the frontal and sagittal planes. The level of the head and scapulae in the frontal plane, the curvature of the spine and the level of the iliac crests help define the upper torso in space. Muscle wasting helps determine the chronicity of the problem and may also guide the remaining assessment of the presence of an upper versus lower motor neurone aetiology. The alignment of the lower limbs — with particular reference to the sagittal plane alignment at the hips and knees and transverse plane alignment at the knees and feet helps define the lower torso in space. A limb length inequality should be corrected at this stage using blocks so as to determine the magnitude of the curvature of the spine with the limb lengths equalised.


The normal spine has a convexity backwards in the thoracic region (kyphosis). The cervical and lumbar spines are concave backwards (lordosis). Seen from the side the thoracic kyphosis may be accentuated. If the angulation is sharp the dorsal prominence is called a kyphus. In low back pain the normal lumbar lordosis is often absent and the lumbar spine is held rigid and straight. Seen from behind, the spine may seem tilted to one side or rotated. Lateral curvature of the spine associated with rotation is known as scoliosis.


After thorough inspection, the prominences of the spinous processes and intervening ligaments are felt. Often a deformity or step is more easily felt than seen. The underpants must be low enough so that the lumbosacral joints and sacrum are visible.


Movements of the spine are next observed, beginning with flexion (touching the toes). Most flexion takes place at the lumbar spine. Isolating the precise range of motion in the spine in the various segments of the spine is difficult. Forward flexion is often a combination of movement at the spine and pelvis/hips. Assessment often entails the pelvis being stabilised during the examination process. With the pelvis stabilised, the range of forward lumbar flexion may be assessed. You may measure the change in distance between a fixed point on the sacrum such as the spinous process adjacent to the S2 dimple and the first lumbar vertebra. The patient may show deviation to the painful side on forward flexion. While hip flexion may simulate spinal flexion, the lumbar lordosis will be observed not to unwind, the spine remaining stiff — in this situation the excursion between lumbar spinous processes remains unchanged as flexion proceeds. Whole spine rigidity may be evident in ankylosing spondylitis; this may be associated with a decreased chest expansion during inspiration of less than 2.5 cm.


Extension is tested by asking the patient to lean backwards. Lateral deviation is tested by asking the patient to bend sideways and observing how far the extended hand slides down the leg (normally it can reach to below the knee). Rotation is tested by asking the patient to twist their trunk while keeping the feet together. The effect of pelvic movement is then eliminated by grasping the pelvis and fixing it while the movement is repeated. Most spinal rotation occurs in the thoracic spine.


Kyphosis and lordosis can be mobile (postural) or fixed (structural). Postural kyphosis is very common. In the setting of a kyphosis one may consider adolescent osteochondritis (Scheuermann’s disease), osteoporotic crush fractures, ankylosing spondylitis, Paget’s disease, vertebral crush fractures resulting from malignant vertebral deposits and spinal tuberculosis as differential diagnoses.


If scoliosis is present, the position of the primary (largest) curve is noted and whether there are secondary curves above and below to compensate. A balanced deformity is one in which the occiput remains over the midline. This may be assessed using a plumb line dropped from the seventh cervical vertebra — the vertebra prominens — and the sacrum. The plumb line should pass through the centre of the sacrum. The degree of shift of the occiput from the midline, often taken as the middle of the sacrum, may give an indication of severity of the imbalance. The scapula will be unduly prominent on the convex side and the hip bone on the concave side. The rib angles may protrude on the convexity of the curve.


The effect of spinal flexion and sitting on the scoliosis is noted. In postural scoliosis, the deformity disappears with forward spine flexion (forward bend test) or on sitting. Postural scoliosis may be due to the person’s posture or it may be compensatory for a true limb length inequality or an apparent limb length inequality due to fixed abduction or adduction hip deformities.


In fixed (structural) scoliosis, the deformity persists or becomes more prominent on flexion and is unaffected by sitting.


The patient is finally asked to stand back to a wall, when normally feet, buttocks, shoulders and occiput make contact.


With the patient still standing, they are asked to squat in order to assess the strength of the proximal thigh musculature — particularly the quadriceps. The strength of the gastrocnemius is determined by asking the patient to stand on tiptoe. Compression of the first sacral nerve root may lead to an inability to stand on tiptoe. This may be associated with a reduced or absent ankle jerk on the same side (also a first sacral nerve root test). The patient is also asked to stand on their heels with the toes elevated to test the strength of ankle dorsiflexion. They can be asked to walk in these postures to isolate both sides.


The patient is now examined prone on the couch. The step up to the couch affords the opportunity to test the ability to step up on each leg, in turn.


Examination with the patient prone. The prominences of the spinal processes are rechecked and any bony or soft tissue tenderness observed. The bulk and tone of spinal and buttock muscles are noted. The sacroiliac joints are palpated for tenderness and hip extension tested. One hand may be placed on one side of the pelvis and the other hand used to raise the opposite leg into extension; this results in rotation at the sacroliac joints. It is important to note that when the fourth lumbar nerve root is compressed the patient will also experience pain radiating down the anterior aspect of the thigh with prone extension of the hip joint. This is called the femoral stretch test. The patient is now asked to turn over and is examined supine.


Examination with the patient supine. A careful neurological examination of the lower limbs is performed, starting with inspection for wasting or other signs, followed by an assessment of tone, then a systematic examination of muscle strength, comparing each side to the other, as well as with your expectation of normal. It is best to start distally, as pain can compound the assessment of proximal strength. Dorsiflexion of the toes is important as this may be reduced in L5 lesions. Inversion and eversion of the ankles should be tested, as well as dorsi and plantar flexion, then flexion and extension at knee and hip. In interpreting these observations, it is essential to be familiar with the myotomes and dermatomes, as outlined in standard anatomy texts.


Subsequently, the deep tendon reflexes should be examined. Unusually brisk reflexes may indicate upper motor neuron pathology, while reduced reflexes suggest lower motor neuron disturbance. The plantar reflex is also important.


Subsequently, sensory function should be assessed in all dermatomes in a sytematic fashion. The patient may report subjective differences in sensory perception rather than absolute numbness. In spinal cord lesions, you may observe specific alteration in proprioception and vibration sense if the posterior columns are disturbed or temperature and pain sensation if the spinothalamic tracts are abnormal.


Subsequently, the straight leg raising (SLR) and flexed leg raising tests are performed. It is best to elevate the flexed leg first to observe the patient’s response, then perform rotation and adduction/abduction of the hip to assess for pathology at the hip/pelvic level. Subsequently, the extended leg is lifted actively by the patient and then by the clinician until pain in the buttock, leg and/or back is felt and the angle at which this occurs is observed. The leg should be raised slowly and the knee kept at full extension during this manoeuvre. At this level, if the knee is flexed the pain of nerve root irritation should abate and, if the ankle is dorsiflexed, the pain is exacerbated. Sudden firm pressure on the tibial nerve in the popliteal fossa may elicit further pain — sometimes known as the bowstring sign — and confirm an underlying organic aetiology. Straight leg raising of the opposite leg giving rise to pain in the affected leg is known as crossover pain, suggesting that the disc lesion is in the axilla of the nerve root or medial to the nerve root (Fig 5.1). Sciatica due to nerve root compression in the lumbar spine will typically cause pain down the back of the leg on the straight leg raise but not with the flexed leg raise. Cadaver studies have shown that the L5 and S1 nerve roots move by 2 cm or more in the spinal canal during the SLR.



The knee and ankle joints must be examined. Arthritis of the hip or knee combined with low back pain due to spondylosis may confuse the clinician into thinking that the leg pain may be due to the spinal degeneration and that spinal surgery might be considered. It is important to note that severe chronic arthritis can cause muscle wasting, particularly of the quadriceps, but would not cause changes in the reflexes nor sensory change.


Femoral and pedal pulses are checked and capillary return to the toes. This may assist in the differentiation of lumbar canal stenosis from peripheral vascular disease. The groin and abdomen are palpated for any masses or tenderness.


Rectal and vaginal examination should not be omitted if any uncertainty exists as to the precise diagnosis and are mandatory in the setting of symptoms suggesting a cauda equina syndrome. You must be concerned that a cauda equina syndrome may be present if: there is pain in the perineum or both legs; there is unilateral or bilateral leg weakness; or there is a sensory deficit in the perineum, buttocks, posterior aspect of the legs and feet, that is, the sacral dermatomes (stand on S1, sit on S3 and S4 and the pee runs down S2) and both ankle jerks are compromised. Rarely, compression in the sacral canal can cause sphincter and perineal problems but spare all lower limb functions.


Non-organic pathology may also require exclusion with the assistance of a series of signs described by Waddell. Tenderness in such cases is superficial and non-anatomical. Simulated axial loading such as pushing down on the patient’s skull or shoulders is reported as painful in the lumbar spine as is simulated rotation of the lumbar spine by rotating the shoulder and pelvis together. The pain, if present, should not be increased by this manoeuvre. Distraction tests such a extending the knee joint while the patient sits on the edge of the examination couch should produce the same pain as a straight leg raise. If it does not then the pathology may be non-organic. Regional weakness and giving way that cannot be explained on a neurological basis — myotomal/dermatomal or peripheral nerve in their pattern of involvement — should also raise suspicion. Overreaction during the examination process, such as facial expressions, tremor and collapsing, may also be suggestive of non-organic pathology. However, you must also be sensitive to cultural differences that may result in these overreactions. Inconsistency between different phases of the assessment may also be a clue. It is very common for there to be some non-organic overlay to a fundamentally organic situation.



5.2 Back pain


Chronic back pain is one of the most frequent problems in patients presenting to a hospital outpatient clinic. Chronic back pain is defined as pain persisting beyond the time course of healing for an acute injury (often taken as three months because 90–95% of low back pain settles within a three-month period). Pain may be related to chronic disease. In the case of degenerative disease, attacks of disability may recur episodically for years. In the case of tumour or infection, the disease tends to follow an inexorable progressive course. It is important, yet often difficult, to define those experiencing chronic back pain with an underlying physiological basis from those with no underlying organic pathology — particularly as pain becomes increasingly disassociated from an underlying physiological basis with the passage of time.


Radiation of back pain is common. Radiation may take the form of a vague diffuse ache in the buttock and lower limb or may be severe and radiate along the well-defined course of the sciatic nerve distribution. Evidence of nerve root compression with sensory and motor loss usually indicates mechanical compression from disc prolapse or other pathology. The numbness and paraesthesia of nerve compression may be postural. Morning stiffness easing with activity and reappearing near the end of the day suggests arthritis. Litigious and work-related associations of chronic back pain are very common and may be difficult to assess and treat.




Special tests in the assessment of spinal pain


A CT or MRI of the lumbar spine as well as FBE, ESR and CRP is always required where a patient presents with persistent or recurrent back pain. Plain radiology is a very blunt tool in diagnosis but remains useful in understanding spinal posture and instability (erect and supine views, with flexion/extension when appropriate) Currently, the MRI scan is the investigation of choice for detailed understanding of persistent cases or those requiring surgery. Many consider that it should replace CT as the first-line investigation as it avoids radiation and is more accurate. The unique challenge in spinal assessment is the high incidence of abnormal findings that are asymptomatic or minimally relevant to the presenting problem. An accurate clinical assessment is paramount in understanding the significance of the radiological findings.



1 Chronic lumbar ligamentous strain


This term is one of many used to describe the condition of persistent backache without demonstrable pathology. The condition is common in unskilled manual workers of both sexes and tends to recur with physical activity and to be work related. Depressive illness is a common association. The onset of the pain may also be dated from a specific injury, occasionally from an operation or from a past medical illness. The pain is diffuse, radiates widely but usually without definite anatomical features and tends to be worse on stooping and lifting. Usually, clinical examination yields no abnormal objective physical signs. Pain on straight leg-raising is variable. In nearly half the patients presenting with chronic back pain, a precise pathological diagnosis is not possible. In contrast to the diffuse pain of chronic back strain, patients with focal pathology usually have more localised pain at or near the site of the lesion. X-rays, CT and MRI are normal or a minor degree of spondylosis is seen. A rehabilitative approach is generally recommended, and often helpful.


A history of pain after lifting at work is common with chronic and recurring back pain. The WorkCover context complicates the situation considerably. Most patients still get better with rest, gentle activity and time. In those cases that pass into chronic pain, the significance of neurosis or malingering in the pathogenesis of this litigation-linked condition can rarely be determined with absolute assurance. True malingering in the sense of complete fabrication of a set of symptoms and signs is uncommon; exaggeration of symptoms and signs in the absence of demonstrable organic disease and persistence of symptoms and signs while litigation is pending is common.



2 Degenerative disc disease, spondylosis and osteoarthritis


With disc degeneration, especially following recurrent disc prolapse, gradual flattening of the disc and displacement of the posterior facet joints occur, eventually gives rise to osteoarthritis in those joints (Fig 5.2). A past history of lumbar pain is common, with subsequent recurrent attacks of pain over a period of several years. The onset of such attacks is often related to exertional trauma, such as repetitive bending or lifting a weight, or strain from sitting in an uncomfortable position during a long journey. Sciatic radiation of the pain to the buttock and sometimes down the backs of the legs, on one or both sides, is common. With the development of osteoarthritis of the facet joints, pain becomes constant and nocturnal. On examination, tender areas may be felt over the spine. There is limitation of all lumbar spine movements and residual neurological signs of disc prolapse, such as an absent ankle jerk, may be present. Most instances of chronic recurring back pain fall into this category; however, it is surprising how many patients have minimal symtoms despite impressive changes on scans.










Diagnostic plan


Collapse or destruction of the vertebral body, narrowing of the disc space and soft tissue changes may be assessed on plain X-ray, but this test is relatively insensitive. The most common X-ray features found in the spine are those of chronic disc degeneration, spondylosis, osteoarthritis and sometimes spondylolisthesis. In the case of spondylolisthesis, the early signs of narrowing of the anterior disc space and displacement of the more proximal vertebrae against the one below are seen best on the lateral view. The disc spaces most often involved are those between L4 and L5 and L5 and S1. Later, marginal osteophytes appear at the edge of the disc and there is increased radiolucency of the vertebral body. Lateral and oblique views may show facet joint malalignment and osteoarthritis.


CT scanning and more recently MRI have significantly improved the safety of investigation by reducing the need for contrast myelography in the investigation of a patient for disc prolapse with signs of nerve root impingement. The strength of MRI scanning is the ability to characterise pathological tissue plus the ability to provide multiplanar imaging without the use of ionising radiation. However, the clinician ordering the MRI should have a working diagnosis that the MRI will confirm. This is because the test has a high sensitivity for detecting pathological processes at many spinal levels — some of which may be asymptomatic. However, MRI is currently the test of choice, if available, and is the only test required in most cases.


Full blood examination (FBE) and erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are usually normal but, if they are abnormal, they give clues to serious causes such as infection, malignancy and ankylosing spondylitis.



Treatment plan


The treatment of chronic lumbar ligamentous strain and chronic disc degeneration are similar. The inital approach is conservative and rehabilitative, teaching the patient how to improve posture and lift with minimal strain and active exercises to strengthen the spinal muscles. Physiotherapy based on the McKenzie or Pilates method is often helpful. Hydrotherapy can be helpful in severe cases. Local heat and short-wave treatment are often beneficial symptomatically for acute exacerbations. If these measures fail after several weeks of treatment, external corset support may be useful. The obese patient is urged to lose weight. The majority of patients improve with conservative treatment, but patience is often required because this may take months in some cases. In the case of work-related chronic back strain, recovery often must await compensation payment.


Patients with sciatica without neurological deficits may benefit from epidural steroid injections. Steroid injections into facet joints, and local anaesthetic injections or radiofrequency applications to the nerves supplying these joints, may help pain due to facet joint arthtitis. Sometimes the condition needs to be managed in a chronic sense. Work or lifestyle change may be very important in controlling symptoms. Swimming, running and cycling are generally good forms of exercise for those with chronic spinal problems, whereas competitive sport may promote exacerbations of pain and disability.


Patients with severe and unremitting sciatica, or those with significant neurological deficits, may be best treated with surgery after careful clinical and MRI assessment. The results of surgery for suitably selected cases are good in the modern era, but surgery for low back pain without well-defined pathology is associated with poor results.


Spondylolisthesis with neurological symtoms or signs may require surgery, typically with decompression of the nerves followed by fusion using internal fixation and bone grafts. Infection needs prompt diagnosis, identification of the organism by blood cultures, direct radiological aspiration or surgery, followed by prolonged intravenous antibiotic therapy. Epidural abscess is an emergency that requires urgent surgery in many cases, as well as antibiotics.


Once bone mass is lost in patients with osteoporosis the disorder is extremely difficult to correct. A combination of calcium, biphosphonates and vitamin D may be helpful in some patients, after assessment by a physician. The fractures will heal and symptoms typically will improve with gentle physical therapy and time. Surgery has no role unless severe neurological deficits are present.


Radiotherapy will often assist the relief of pain from metastatic disease of the vertebrae, and prevent further progression. Radical surgical excision and reconstruction can be considered in selected cases. Spinal cord compression is a common sequel of untreated spinal metastases. The patient may benefit from urgent surgery to decompress the cord, supplemented with internal fixation to prevent later progression, then radiotherapy and/or chemotherapy.

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Jul 18, 2017 | Posted by in GENERAL SURGERY | Comments Off on Back and related limb neurological problems

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