Acquired brain injury: stroke, cerebral palsy and traumatic brain injury

6 Acquired brain injury


stroke, cerebral palsy and traumatic brain injury



CHAPTER CONTENTS


































Part 1 Stroke





Mortality


Stroke is a devastating condition for both patients and carers, with a high mortality rate throughout the first year after the lesion: 30% at 3 weeks, 40% at 6 months and 50% at 1 year [8]. Morbidity is high, with 12% estimated to be in long-term care 1 year after the event [9]. The risk of recurrence is also high: 7% for at least 5 years after the initial stroke and 15 times the stroke risk for the general population [10]. The figures suggest that each health district can expect 550 patients to present with stroke each year and each general practitioner can expect to see four or five new cases a year and be caring for 12 survivors, of whom seven or eight will be disabled [11]. Stroke is therefore a major financial burden to the NHS and consumes more than 4% of total NHS expenditure and more than 7% of community health and social care resources [12].



Risk factors


There are many health factors which appear to predispose a patient to stroke. Age is the most important factor [13], but in general raised blood pressure [14], smoking [15] and alcohol consumption [16] are associated with a greater risk of occlusive and haemorrhagic stroke. Diabetes mellitus is associated only with occlusive stroke. Other factors that may be important are obesity, poor diet, febrile illness, oral contraception, taking hormone replacement therapy and, in some cases, wide seasonal variation in temperature, although this can be either extreme cold or heat [17]. It has also been suggested that the seasonal availability of vitamin C may be a factor [18], although with the wide variety of non-seasonal foods now available this may not be an issue in industrial nations.



Diagnosis



Differentiation from other diseases











Medical treatment



Acute


Most patients with stroke are admitted to hospital, although some, those with generally less severe symptoms, remain at home for their nursing and subsequent rehabilitation. In practice it is difficult to be certain how many people are not admitted to hospital because they are not routinely recorded.


A welcome innovation has been a widespread advertising campaign to alert the public to the first signs of stroke [24], emphasizing that stroke should be recognized as a medical emergency requiring fast admission and specialist management. Patients who have suffered a stroke remain at increased risk of a further incident: therefore secondary prevention is part of treatment.


Measurement of the underlying structural changes within the brain has only recently become routine. Now the idea of cell death or apoptosis is better understood, it is becoming clear that there are two types of damage. Firstly, the focus of the stroke, where the cells are deprived of oxygen, for whatever reason, and subsequently die, and, secondly, the so-called penumbra or area surrounding the focal point, where the cells are damaged by pressure from temporarily swollen tissues but may not necessarily be destroyed. Since the penumbra has the potential to be reperfused there is a limited time period for interventions to be effective before the cells die. It would be desirable to increase the blood supply to the penumbra without increasing the haemorrhage.


Considerable research has been undertaken to investigate drug treatment in the immediate aftermath of stroke. Drugs such as aspirin and heparin seem to have some purpose in preventing further damage immediately after the stroke but two recent major studies have not entirely supported their use.


The International Stroke Trial investigated 19 435 patients within 48 hours of acute stroke and randomized them between two different doses of heparin or placebo [25]. The design also randomized patients to receive daily aspirin or no aspirin. The researchers used a 2×2 factorial design with patients randomized to one of four possible groups: heparin and aspirin, aspirin or heparin alone or no treatment. Treatment lasted 14 days or until discharge, if sooner.


The results from the International Stroke Trial study showed that there was no overall benefit in mortality or limitation of brain damage from the use of heparin; indeed, there was a slightly higher – 9 per 1000 – rate of haemorrhagic strokes and more deaths within 14 days. Neither heparin regimen gave any clinical advantage at 6 months. There was no interaction between heparin and aspirin in the main outcomes.


The other major study, the Chinese Acute Stroke Trial [26], randomized 20 000 patients to daily low-dose aspirin or a placebo, also within 48 hours of the stroke. Treatment lasted 4 weeks. The Chinese Acute Stroke Trial study showed that aspirin started in the acute stage was associated with small benefits. The difference in death rates between the aspirin and control groups was only 0.5%. Combining the data from these two very large trials detects a small treatment effect for aspirin, thus supporting the early prescribing of aspirin, as long as continuing haemorrhage has been excluded. As aspirin is prescribed in any case for long-term prevention it becomes imperative that CT scans take place routinely very soon after stroke.


Thrombolytic drugs have also been investigated, particularly tissue plasminogen activator (tPA, alteplase) given within just 3 hours of an acute ischaemic stroke. The most recent Cochrane review [27] balances the increase in deaths within the first to seventh days and deaths at final follow-up with the reduction in disability in the survivors. It suggests that intravenous recombinant tPA may be the best method of delivery but is cautious about recommending general use.


However the current advice given to physicians [28] is that thrombolytics may be given but haemorrhage must definitely be excluded and that the patient should be in a specialist centre with appropriate experience and expertise.





Prognosis



Body structure and function, activity and participation


The effect of stroke, or indeed any neurological condition, is described in varying ways. The International Classification of Functioning, Disability and Health (ICF) suggests that an individual’s disability and resultant function is a result of the interactions between his or her health condition and contextual factors such as the physical environment or social attitudes [33]. A full description is included in this chapter, although it applies equally to the others.


ICF highlights the relationship between problems with body structure and function and the individual’s level of activity and participation (Table 6.1).


Table 6.1 Definitions of major International Classification of Functioning, Disability and Health categories


















Category World Health Organization definition (33)
Body structure Anatomical parts of the body such as organs, limbs and their components
Body function Physiological functions of body systems, including psychological functions
Activity The execution of a task or action by an individual
Participation Involvement in a life situation

ICF goes on to identify three levels of functioning of the human: at the body level, at the whole-person level and within society in general.


Disability involves functional difficulties in one or more of these levels and may include the following:





Contextual factors also contribute to the overall disability. External environmental factors might include steps into the person’s home limiting access or uneven footpaths en route to the local shops posing a risk of tripping. Personal factors might include the individual’s personal coping style and past experience as well as educational and social background.


Disability is often measured in terms of the ability to carry out activities of daily living (ADL) using scales such as the Barthel ADL Index. The main emphasis in stroke research has been on the domains of physical activity and self-care but it is useful to remember that the World Health Organization definition of disability is much broader than this.


The relationships between impairments and activity or participation restriction are not fixed. Individuals with very severe impairment may participate fully within their local community with an appropriate level of support. Another individual with relatively mild impairment may be severely restricted in activity and participation, possibly due to substantial impact of contextual factors. This highlights the complexity of carrying out research in the stroke population.



Effects of stroke


The primary effect of stroke is impairment of muscle function caused by motor and/or sensory deficits commonly affecting the face, arm and leg on the contralateral side. This will result in the characteristic hemiparesis or hemiplegia leading to physical disability of a temporary or permanent nature.


Unfortunately there are many other possible effects, depending on the site of the brain lesion and the quality of the poststroke care. Among them are:












Depending on the site of the lesion there may be varying degrees of speech loss or swallowing difficulties and there is a real danger of food aspiration in the acute stage of stroke. Most patients with moderate to severe stroke are incontinent at admission, and many are discharged still incontinent. Both urinary and faecal incontinence are common in the early stages and need urgent management in order to prevent these problems delaying the patients’ eventual rehabilitation. Urinary incontinence directly after stroke is an indicator of poor prognosis for both survival and functional recovery [34]. Care must be taken to prevent infection.


Anxiety is an equally common problem accompanied by feelings of fear and apprehension with physical symptoms such as breathlessness, palpitations and trembling. The specific causes of anxiety after stroke are not known; it may simply be a product of the sudden physical disability or may more closely resemble an anxiety disorder and require antidepressive drug treatment. Anxiety after stroke has certainly been shown to be associated with increased severity of depressive symptoms and greater functional impairment [35].


Long periods of inactivity produce a danger of skin breakdown and the possibility of pressure sores is increased if the patient is also incontinent. The lack of voluntary movement also increases the risk of deep-vein thrombosis and pulmonary embolus. Early mobilization after stroke has been shown both to cut rates of poststroke depression by 50% and also to be cost-effective [36, 37]. This has implications for early acupuncture treatment of this condition. The link between exercise and general feeling of well-being and mood elevation is well documented in healthy subjects [38], and the chemical action of acupuncture has often been compared to that of exercise [39].


A further complication of recovery is spastic hypertonia associated with exaggerated deep tendon reflexes. This is often associated with central nervous system disorders due to lesions in the brain that affect descending tracts normally inhibiting spinal reflex pathways. The resulting excessive muscle tone can cause many problems, including loss of free movement, difficulties performing daily activities and pain [40]. It may also cause the limb to become ‘frozen’ or fixed in an uncomfortable position.


Pain is most common in the affected shoulder. It is to be hoped that it is less often present now that much emphasis is placed on correct positioning of the paralysed limbs [41]. Unfortunately the initial loss of muscle tone in the hemiplegic arm often results in damage to the capsule with subsequent pain. Use of functional electrical stimulation can help prevent this unpleasant complication [42].


Falls are not uncommon in elderly patients even if they have not suffered a stroke. Paretic limbs become osteopenic or less dense and since the stroke patient is likely to fall to the affected side, poststroke fractures are a frequent complication in the process of rehabilitation. Fear of falling can be damaging too, leading to reduction in possible mobility and social withdrawal.



Patterns of recovery


The aim of all treatment should be independence in self-care within a year after the stroke. This is achieved in a range between 60% [43] and 83% [44] of surviving patients, both measured at 1 year after stroke. However the same data suggest that between 16 and 31% may be institutionalized by the end of the year.


Recovery of rolling, sitting balance, transfers and walking among patients referred for rehabilitation seems to follow a relatively predictable pattern over the first 8 weeks [45]. The majority of muscle recovery occurs within the first 3 months after the stroke with subsequent recovery taking place at a slower pace [46]. Some useful recovery still occurs between the sixth and twelfth months. In the hemiplegic hand it is thought that if there is no active hand grip after 3 weeks there is unlikely to be much improvement [47].


The accepted wisdom within the physiotherapy profession is that there is little to be gained from the rehabilitation process as late as 2 years after the stroke, but there may be unused potential for physical improvement in the period before this cut-off, depending on previous access to treatment. Overall recovery is thought to be adversely affected by the patients’ age [48]. This assumes that there may be co-pathology, including mobility problems such as osteoarthritis.



Recurrence


One in five strokes is a recurrent stroke and a patient who has had one stroke is at 10-fold increased risk of another [49]. Despite similar neurological impairments, patients with recurrence on the opposite side to their original episode tend to have markedly more severe functional disability after completed rehabilitation than patients with an ipsilateral recurrence, implying that functional ability to compensate is decreased. These figures serve to underline the importance of a prophylactic dose of aspirin or even acupuncture.



Stroke and physiotherapy



Current physiotherapy


Physiotherapists are an important part of the hospital rehabilitation team and, working alongside the occupational therapists, are particularly concerned with regaining functional movement in the paralysed limbs. In order to achieve this many of the primary movement patterns need to be relearned by the patient. Progress is often hindered by the state of the muscle tissue, which may exhibit weakness, spasticity or no tone at all, remaining flaccid. Progress can also be inhibited by the development of contractures and resulting pain produced by poor postural positioning in the bed and chair. This will also be made worse by early, incorrect attempts at movement.


The modalities used by the physiotherapist are many and varied, based essentially on the retraining of physical movement and incorporating forms of biofeedback to retrain balance and proprioception [50], functional electrical stimulation [51], gait retraining and treadmill training [52]. Transcutaneous electrical nerve stimulation (TENS) has also been used successfully [53], usually utilizing acupuncture points. Approaches to treatment vary but may also include techniques drawn from the Bobath approach, movement science and, on occasion, proprioceptive neuromuscular facilitation. Research has failed to identify substantial differences between the different approaches but a clear finding is the need for intensive training [54]. More research on the individual components of rehabilitation is still required.

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May 25, 2016 | Posted by in NEUROLOGY | Comments Off on Acquired brain injury: stroke, cerebral palsy and traumatic brain injury

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