Management of motor neurone disease

Journal of the Neurological Sciences, 1984, 6 4 : 6 5 - 7 1

65

Elsevier

MANAGEMENT OF MOTOR NEURONE DISEASE

M A L C O L M J. C A M P B E L L L2'* and P A M E N D E R B Y T M

tBristol Royal Infirmary and 2Frenchay Hospital, Bristol (Great Britain)

INTRODUCTION

Motor neurone disease (MND) or amyotrophic lateral sclerosis (ALS) is a progressive, non-inflammatory, degenerative disease of motor nerve cells in the central nervous sytem of adults. It is invariably a fatal condition with a mean course of 3-4 years, although about 20~ of patients survive 5 years and 10~ survive 10 years (Mulder and Howard 1976). It is an uncommon but ubiquitous disease with a prevalence of 2.5-7 per 100 000 population, although pockets of high prevalence exist in certain tribal communities of the Western Pacific Islands, especially on Guam. There is a 5-10~o familial incidence in most other countries. The combined loss of function of the upper motor neurones (UMN) in the parietal cortex with that of the brain stem and spinal lower motor neurones (LMN) causes a mixture of spastic paralysis and flaccid muscular weakness and wasting. Patchy and asymmetrical dysfunction of these motor neurones is common, c/tusing several different clinical syndromes. The commenest presentation is of progressive LMN weakness and wasting of the limbs, or progressive muscular atrophy; signs of spasticity and upper motor neurone involvement almost invariably appear later in these cases. Charcot (1874) coined the term amyotrophic lateral sclerosis to describe the pathological changes in the spinal cord of clinical cases where spasticity and UMN signs predominated in the absence of muscle wasting, but such a picture is generally very short-lived. In approximately 25~o of patients, the weakness commences in the musculature supplied by the cranial nerves and presents with difficulty in speech, swallowing or respiration, the so-called progressive bulbar palsy. Despite a full knowledge of the clinical picture and pathological fmdings of the disease for more than a century, the cause of MND remains unknown and hence not surprisingly no specific form of treatment is known. Few drugs have been shown to have any symptomatic value in MND. The anti-cholinesterase drugs may be of short-lived benefit in some patients, especially those with progressive bulbar weakness. A myasthenic-like neuromuscular fatigue with response to anti-cholinesterase drugs has * Consultant Neurologist. * * Principal Speech Therapist. 0022-510X/84/$03.00 © 1984 Elsevier Science Publishers B.V.

66 been demonstrated electrophysiologically in MND (Lambert and Mulder 1957). These drugs are thought to aid neuromuscular transmission in damaged terminal nerve endings or more probably in weak re-innervative nerve sprouts (St~lberg et al. 1975). Muscle spasticity and painful spasms may be eased by Baclofen, a synthetic GABA-Iike inhibitory drug. Anti-cholinergic drugs may be helpful in the case ofhyper-salivation (see later). However, we are not totally powerless in treating or managing the clinical effects of the disease and to show this disease and this is the purpose of this paper. UPPER LIMB WEAKNESS

The commonest presentation of MND, occurring in approximately 40~/o of patients, is of progressive weakness and wasting of muscles of one upper limb, usually commencing in the hand. The muscles of the thenar eminence are commonly involved with loss of adduction and opposition of the thumb. This causes impairment of pinch grip between thumb and index finger resulting in loss of fine finger control. The patient experiences difficulty in picking up small objects and in dressing, especially where buttons are concerned. Where the dominant hand is involved there is also progressive difficulty with writing and also with the more mundane but important day-to-day tasks of holding toilet paper, etc. Some benefit may be obtained in the earlier stages of this disability from the use of an adduction splint which simply holds the thumb in the adducted position. Corrective surgery by tendon transfer of a long flexor tendon has been tried in the past in a few cases but the progressive disease overtakes any re-education of thumb function. The problem of dressing may be eased by the use of a button hook or later by a switch to Velcro fastenings. Progressive wasting of the small intrinsic muscles of the hand causes clawing of the fingers and a generally useless hand. Localised weakness of the forearm extensor muscles causing wrist drop may result in weakness of hand grip which is more apparent than real, as may be demonstrated when the wrist is held in extension by a "cock-up" splint. Active physiotherapy has been claimed to be of benefit in MND (Lehman 1959; Sinaki and Mulder 1978). A course of general exercise will maintain full joint mobility and prevent contractures. The exercises should also encourage the compensatory hypertrophy of surviving motor units which is known to occur both in clinically and sub-clinically affected muscles. This functional compensation may be so efficient in some patients that it is claimed that up to 80-90~o of motor units in a muscle may be lost without significant loss of strength (McComas et al. 1975). The typical course of the disease is for progressive involvement of other muscles of the same limb and then spread to the opposite upper limb to occur before lower limb or butbar muscle involvement is noted. LOWER LIMB WEAKNESS

The initial manifestations of MND in the lower limb may be simply spastic stiffness rather than weakness. This may be relieved by judicious use of the anti-spastic

67 drug Baclofen at doses of 10-30 mg 6-8 hourly, although excess therapy often uncovers latent weakness. Other known anti-spastic drugs are rarely helpful and the peripherallyacting anti-cholinerglc drug, Dantrolene may cause an alarming weakness in this disease. Progressive muscular atrophy affecting the legs may result in weakness of ankle dorsiflexion causing foot drop, or instability around the joints. In mild cases of foot drop, or instability around the ankle, light-weight calf-length boots rather than shoes may give adequate compensation. Alternatively a polypropylene moulded appliance (Harhill splint) fitting inside the shoe and extending up the posterior aspect of the lower leg with a strap around the calf may be helpful. In more severe cases of weakness a sturdy external caliper with toe-spring attached to the shoe or boot is required. Weakness of the quadriceps muscle causing sudden instability of the knee in standing or walking necessitates the additional support of a stick or crutches, but may be helped by a long-leg external caliper with knee-locking device. Progressive bilateral leg weakness leads to increasing reliance on a suitable wheelchair to maintain mobility. Localised leg weakness restricting driving control can be compensated in suitable cases by conversion of the car to hand controls. DYSPHAGIA AND EXCESS SALIVATION

Progressive weakness of the oro-pharyngeal muscles presents with difficulty in speech and swallowing. Among the early symptoms is often a detectable slowness in drinking when the patient finds it difficult to take successive swallows without pausing between them. In addition, there is a loss of co-ordination of the tongue which can cause difficulty in propelling solids and liquids around the mouth and then back towards the pharynx. Dysphagia for liquids is more common than for solids, although swallowing solids becomes increasingly difficult with the course of the disorder. The symptom of dysphagia may be related to many different causes and it is important in the management of the disorder to identify the site of muscular inadequacy. The remedies for difficulties due to poor lip closure and poor head position are different from those for poor palatal movement or restricted laryngeal lift. The occasional distressing choking which can be related to pooling of secretions mixed with food particles in the hypopharynx, can be so worrying for both the patient and the relatives, that meal times become a very tense period. Thus, conservative management with regard to the best position for feeding, the type of diet that is most suitable and some simple swallowing routines may be most effective in increasing confidence and reducing anxiety. This is important when one considers that, increasing dysphagla leads to inanition contributing to the overall weight loss and weakness. A simple technique used in speech therapy which has been found to be of assistance where spasticity of the oro-pharyngeal muscles occurs in the absence of significant lower motor neurone wasting, is the sucking of an ice cube a few minutes prior to a meal. Additionally, it has been found that the anti-spasmodic drug Baclofen, may be of limited help in alleviating spasm-related dysphagia. Dysphagia due to lower motor neurone weakness and wasting, may be eased by

68 anti-cholinesterase drugs such as Neostigmine 15-30 mg before meals or Pyridostigmine (Mestinon) 30-60 mg 8 hourly, but such benefit is generally short-lived for a matter of weeks or a few months. Occasionally such drugs are not tolerated because of severe limb or abdominal cramps. Often, appropriate advice with regard to diet, avoiding liquids and increasing the amount of semi-solids, will alleviate some of the troublesome symptoms in early bulbar paralysis. Pooling of secretions in the hypopharynx with the problem of spillage into the larynx and trachea may not only cause severe unpleasant choking but also carries the risk of inhalation pneumonia. It may be helped by crico-pharyngeal myotomy (Mills 1973). This is a relatively simple operation which lowers the resting intrapharyngeal pressure and has been reported as beneficial in a third of ALS patients with severe dysphagia (Lebo et al. 1976). In extreme cases tracheostomy and inflation of a cuffed endotracheal tube during feeding is necessary. Total laryngectomy is rarely justified in such a progressive disease. Inanition and resulting weakness eventually necessitate assisted tube feeding. A small bore plastic nasogastric tube is well tolerated and may be left unchanged for several weeks. A gastrostomy or oesophageal tube is rarely necessary or justified, Fully balanced nutrition may be given by these means which can prevent general debility. Drooling may be controlled in milder cases by the use of anti-cholinergic drugs, Atropine sulphate 0.6-1.2 mg 6-8 hourly, or one of its synthetic analogues e. g. trihexyphenidyl HCI (Artane) 2-4 mg 8 hourly, may be adequate but sometimes cause troublesome side-effects e.g. blurred vision or hallucinations. Alternatively, salivation may be reduced by bilateral transtympanic neurectomy under local anaesthesia (Zalin and Cooney 1974). This divides the parasympathetic nerve supply to all the salivary glands and effectively lowers salivation by up to 95 ~o. Xerostomia is rarely a problem afterwards. DIFFICULTIES WITH SPEECH AND COMMUNICATION

The initial difficulty with speech is often difficult for either the patient or the neurologist to categorise but is considerably aided by assessment by a speech therapist. The Frenchay Dysarthria Assessment (Enderby 1983) allows a rapid analysis of the components of speech, and indicates the features that may be disproportionately affected. For example, it often appears that the lips and the palate are more severely affected than the tongue at the onset of the dysarthria. During the course of the disorder the type as well as the degree of the dysarthria changes according to the relative involvement of upper or lower motor neurones. Among the early signs of the dysarthria are difficulty with voice modulation, restriction of pitch change and diffiCulty with controlling air flow for whistling or blowing. Early onset of spastieity of the larynx can cause obvious slowness and stif"mess which gives the voice a "strained-strangled quality" to listeners. As the dysarthria progresses the speech is characterised by imprecise consonant production, hypemasality, harsh voice quality and a stow speaking rate (Dworkin and Hartman 1979). The dysarthria tends to deteriorate until any attempt at rapid speech results in a monotonous hypernasal, fiat, drawling sound. Additionally,

69 patients very often are unable to modulate this sound due to uncontrolled inappropriate adduction of the vocal cords. This dysphonia may be complicated by gurgling sounds or coughing fits caused by pooling of secretions in the hypopharynx. Speech therapy is helpful not only in compensating for the physical and psychological effects of dysarthria, but also in examining alternative methods of communication as the disease relentlessly progresses. The initial treatment concentrates on advice which will maximize the intelligibility by encouraging the patient to pace the delivery, reduce his attempt to speak loudly and use other "avoiding" techniques. If one feature of speech is disproportionately affected, particular aids or therapy may be aimed at this area. For example, a palatal weakness causing hypernasality and difficulty in swallowing may be aided by a passive palatal support or a palatal lift; a smaller loop is adequate for mainly spastic weakness. However, labial weakness, which results in difficulty forming P, B, M and W and in maintaining intra-oral pressure for the plosive sounds, can be aided by using lip seal devices and lip pressure exercises. Speech therapy for partially intelligible speech would have different aims. By employing such methods as pointing to the initial letter of each word on a pointing board one can improve the clarity of speech and ease the pressure on the listener. For example, the patient may be asked to point to the initial letters - - I Live In Bristol. As he says the sentence this will slow down his speech and give a visual clue to the listener. Obviously, simple aids should be employed wherever possible and if the patient is able to write, this is the most effective method. A rapid erasure board (magic slate) will speed this form of communication. The therapist has to consider the physical ability of the patient, his requirements and his environment, when assessing him for an aid. One must bear in mind that, on average, a patient with motor neurone disease affecting the bulbar muscles will require 4 different communication aids with the progressive deterioration of his disorder. Following writing, the next most commonly used aids are those involving direct selection by the patient of a letter or symbol which is displayed on a screen or typewriter. Several such aids are readily available commercially, e.g. Lightwriters, Canon Communicators, Sharp Memowriters and Vocaids. All but the last named give an LED or printed output, but the Vocaid has a synthesized speech output which makes it particularly suitable for blind or partially sighted sufferers. It is interesting that there is no one aid which is more suitable than another for this population as the variety of disabilities and concomitant problems renders it necessary carefully to examine which is most appropriate on each occasion. As the disease progresses, it may be difficult for the patient to use his fingers directly to select a letter or word and therefore he may require a "scanning aid". These provide access to a language display on a visual display unit. A cursor light lights up each letter, word or symbol in order. This light can be halted at the desired symbol by the patient activating a switch, which will have been chosen according to the body activity over which he has the most reliable control. Switches may be activated manually, by head tap, heel switch, blowing, eyebrow movement, etc. In the final stages of the disease the generalised weakness commonly obviates switch activation and communication is frequently restricted to the use of eye movements. These may be utilised for

70 communication in many different ways. One is the use of an E-TRAN chart, which consists of a clear perspex sheet with items or letters displayed around the periphery. The chart is held up by the observer in front of the patient, who communicates by directing his gaze at the relevant symbol, allowing the observer to construct the message. Another method of eye communication is by the listener pointing to rows of letters on an alphabet chart and the patient communicating by eye movement when the desired letter of the alphabet is reached; slowly in this way messages can be spelt out. There are now approximately 60 different communication aids available for the speechdisabled patient. None of them is ideal and all require a great deal of patience on the part of the user and receiver. However, people, who a few years ago were unable to express even their basic wishes, are now able to do so because of these technological advances. SEVERE GENERAL DISABILITY

The development of severe generalised muscle weakness leads to restricted mobility and reliance on suitable wheelchairs as mentioned earlier. Manual or powered vehicles exist for indoor and outdoor use, either for self control or assistance by others. Ball-bearing jointed arm pieces will assist limited upper limb function. A reclining arm chair is often the most comfortable seat for daytime care as it allows maximum support for the trunk, head and limbs. It can also be used as an alternative to a bed for night-time use, preferably with a sheepskin cover to reduce the risk of decubitus ulcers. The development of trunk and paravertebral weakness requires adequate support. Severe weakness of the neck muscles can lead to painful flexion or extension of the uncontrolled head and also interference with swallowing and speech. Adequate comfortable cervical collars are seemingly difficult to design and fit. A full chest plate support seems preferable. A full spinal brace is usually heavy and uncomfortable and is rarely acceptable or necessary. Breathing difficulties due to hypoventilation are an end-stage problem in management. These are compounded by weakness of cough and difficultyin clearing the ~ a y . Considerable aid is provided by a portable sucker in such situations even in the absence of a tracheostomy. Assisted ventilation is rarely justified as an elective measure. In certain instances an external negative pressure ventilator has been used as a supplementary support at night when the central respiratory drive is reduced during steep. The psychological disturbance in both patients and family of such cases cannot be overstressed. The maintenance of mobih'ty out-of-doors is important in this. Specially adapted motor vehicles both for self-drive and passenger use are commercially available at reasonable cost. Recently standard family vehicles have been adapted for direct incorporation of the wheelchair-bound patient with means of easy access and anchorage (Ford Freelancer, Metro).

71 REFERENCES Charcot, J.M. (1874) De la scl6rose lat6rale amyotrophique, Progr. M~d. (Paris), 2: 325,341,453. Dworkin, J.P. and D.E. Hartman (1979) Progressive speech deterioration and dysphagia in amyotrophic lateral sclerosis - - Case report, Arch. Phys. Med. Rehab., 60: 423-425. Enderby, P. (1983) The Frenchay Dysarthria Assessment, College Hill Press, San Diego. Lambert, E.H. and D.W. Mulder (1957) Electromyographic studies in amyotrophic lateral sclerosis, Mayo Clin. Proc., 32: 441-447. Lebo, C. P., K. S. U and F. H. Norris, Jr. (1976) Crico-pharyngeal myotomy in amyotrophic lateral sclerosis, Laryngoscope, 86: 862-868. Lenman, J. A. R. (1959) A clinical and experimental study of the effects of exercise on motor weakness in neurological disease, J. Neurol. Neurosurg. Psychiat., 22: 182-194. McComas, A.J., A.R.M. Upton and P.B. Jorgensen (1975) Patterns of motoneurone dysfunction and recovery, Canad. J. Neurol. Sci., 2: 5-15. Mills, C.P. (1973) Dysphagia in pharyngeal paralysis treated by crico-pharyngeal sphincterotomy, Lancet, i: 455-457. Mulder, D.W. and F.M. Howard (1976) Patient resistance and prognosis in amyotrophic lateral sclerosis, Proc. Mayo Clin., 51: 537-541. Sinaki, M. and D.W. Mulder (1978) Rehabilitation techniques for patients with amyotrophic lateral sclerosis, Proc. Mayo Clin., 53: 173-178. St~tlberg, E., M.S. Schwartz and J.V. Trontelj (1975) Single fibre electromyography in various processes affecting the anterior horn cell, J. Neurol. Sci., 24: 403-415. Zalin, H. and T.C. Cooney (1974) Chorda tympani neurectomy - - A new approach to sub-mandibular salivary obstruction, Brit. J. Surg., 61: 391-394.