Common Impairments in Neurological Disorders.

1.Tone disorders

2.Fatigue

3.Disorders of coordination

3.Disorders of motor planning

4.Vestibular Disorders

5.Visuospatial Disorders

6.Sensory disorders

7.Secondary Complications

8. References

Muscle tone disorders

Hypertonia refers to increased muscle tone. Spasticity and rigidity are at times used synonymously with hypertonia. Their usage may lead to confusion, especially if used to explain general hypertonia. Spasticity is used to describe a type of hypertonia that is velocity dependent and usually is accompanied by hyperreflexia. Hypertonia is generally associated with upper motor neuron (UMN) lesions.2 Hypertonia is generally associated with upper motor neuron (UMN) lesions. Assessment can be done using the modified Ashworth scale.

Hypotonia (hypotonus) is a diminution or loss of normal muscular tone, causing floppiness of the limbs. This is particularly associated with peripheral nerve or muscle pathology, as well as lesions of the cerebellum and certain basal ganglia disorders such as hemiballismus–hemichorea dystonia. Weakness preventing voluntary activity rather than a reduction in stretch reflex activity appears to be the mechanism of hypotonia1. Management of hypotonia should not be considered in isolation. Strength, power and neuromuscular control may be key targets when hypotonia is present.2

Rigidity is an increased resistance to the passive movement of a joint which is constant throughout the range of joint displacement and not related to the speed of joint movement.

Rigidity differs from Spasticity in these terms:

  • Resistance in rigidity is present in both agonist and antagonist muscles
  • Resistance in rigidity is not velocity dependent.

Lead pipe rigidity

This type of rigidity is more common and has a ‘lead pipe’ nature of resistance. The resistance is consistent.

Cogwheel rigidity is common in parkinsonism2 the resistance is felt in presence of an underlying tremor; jerky.

Many of the secondary problems associated with rigidity are managed with physical therapy that aims to improve posture, strength, range and general conditioning.

Dystonia is a motor syndrome of sustained involuntary muscle contractions causing twisting and repetitive movements, sometimes tremor, and/or abnormal postures. Dystonic movements may initially appear with voluntary movement of the affected part (‘action dystonia’) but may eventually occur with voluntary movement elsewhere in the body (‘overflow’). The severity of dystonia may be reduced by sensory stimulation; using tactile or proprioceptive stimuli to lessen or eliminate posturing; this feature is unique to dystonia. Dystonia may develop after muscle fatiguing activity, and patients with focal dystonia’s show more rapid fatigue than normal.1

Dystonia can have an impact on many facets of daily life, including chronic pain, balance/mobility, employment and driving.2

The word spasm implies a sudden, involuntary, muscle contraction, which may be painful (cramp).1 In muscle spasms the identification of any trigger is very important, such as skin lesions, pressure ulcers, musculoskeletal pains, ill-fitting splints or infections (especially urinary tract infections). Positioning and postural triggers have implications for lying postures, which impact on sleep and sexual relationships. Seating systems can be designed to minimize spasms and improve comfort and control.2

Dyskinesia may be used as a general term for excessive involuntary movements, encompassing tremor, myoclonus, chorea, athetosis, tics, stereotypies, and hyperekplexia.1 The neurotherapist plays a key role in identification and advice, liaising with the medical team and providing reinforcement about medication dose and timing over the 24-hour cycle.2 

Fatigue

Fatigue can be described as both a sign and as a symptom. As a sign it can be seen through the reduction in muscle strength or endurance with repeated muscular contraction.1 In our case this is the motor fatigue.

Fatigue as a symptom is the enhanced perception of effort and limited endurance in sustained physical and mental activities.1 This what can be described as general fatigue.

Fatigue permeates all facets of life and can impact heavily on employment and quality of life. It is this impact that distinguishes the fatigue experienced in healthy people. Although physical performance can deteriorate with fatigue, the neurotherapist must also consider the additional effects of fatigue on cognitive function2

Exercise interventions should monitor motor fatigue with performance and therapists should design programmes that incorporate frequent rests and consider the risk for falls and injury. This may allow for increased participation as fatigue is often a major barrier.2

Disorders of coordination

The cerebellum is the primary center that is responsible for coordination of movement. Coordination means that there is optimal interaction of muscles to execute the intended movement; the ability to execute smooth accurate, controlled motor responses.

Caused by lesions to the cerebellum or its incoming or outgoing connections.

Defective timing of agonist and antagonist muscle contraction (asynergia) produces jerking, staggering, inaccurate movements (decomposition of movement), which may manifest as intention tremor, dysmetria (past pointing), dysdiadochokinesia, ataxic dysarthria, excessive rebound phenomenon, macrographia, head tremor (titubation), gait ataxia, and abnormal eye movements (nystagmus, square wave jerks, saccadic intrusions).1

The Scale for the Assessment and Rating of Ataxia (SARA) is used for the assessment of cerebellar ataxia.

In sensory ataxia lack of coordination results from impaired proprioception.

Rehabilitation strategies will involve increasing additional alternative sensory feedback through vision and tactile cues. Training techniques that encourage sensory integration can help to improve balance and mobility.2

Tremor is an involuntary movement, roughly rhythmic and sinusoidal.

They are can be classified into:

  • resting tremor

Resting tremor is the most common form of tremor seen in Parkinson’s that can be observed at rest or with an unchanging posture.

  • intention tremor

Intention tremor can involve dyssynergia and dysmetria often with increased oscillations or tremor as limb actively approaches the intended target.

Dexterity often refers to reduced individualized and selective control of each digit of the hand, reduced ability in the complex shaping of the palm/fingers to manipulate objects and reduced fine motor control.2

Disorders of motor planning

Apraxia is defined as the lack of ability to understand an action or perform an action on command or imitation despite an intact motor system and without impairment in level of consciousness. Automatic/reflex actions are preserved, hence there is a voluntary–automatic dissociation.

Bradykinesia is described as an overall slowness of movement with a reduction in the amplitude and speed as the movement is continued. It is common in parkinsonism due to reduction of dopamine.2

Freezing of gait (FOG) is common in Parkinson’s and occurs as brief episodes of an absence or marked reduction of the forwards progression of the feet despite the intention to walk.

Vestibular disorders

Signs of vestibular dysfunction include oculomotor dysfunction such as gaze evoked and/or nystagmus, reduced gaze stability because of altered vestibular-ocular reflex, reduced balance and sensitivity to various types of motion.

Includes disorders such as benign paroxysmal positional vertigo (BPPV), vestibular neuronitis and vestibular hypofunction.

Central lesions that involve vestibular inputs and key integrative pathways in the brainstem and cerebellum can also lead to oculomotor dysfunction, signs and symptoms of imbalance, disequilibrium and vertigo.

Visuospatial Disorders

Homonymous hemianopia (HH) is common after stroke and results in visual field loss on the same side of both eyes. It is caused by any lesion along the retro chiasmal visual pathway.

Unilateral neglect (UN) is a perceptual disorder commonly seen in stroke, more often with lesion in the right hemisphere. Patients with UN fail to respond to any stimuli from the contralateral space (often left), with characteristic ipsilesional bias of head and eye gaze.

Contraversive pushing, often referred to as ‘pusher syndrome’ or ‘lateropulsion’, is another perceptual disorder following stroke that leads to a postural bias towards the hemiplegic side. This disorder can be quite difficult to manage because of the characteristic ‘pushing’ or resistance to postural correction to vertical upright in either sitting or standing. It is thought to be caused by an altered perception of postural verticality.

Sensory Disorders

Sensory loss is both associated with upper and lower motor neuron lesions and can have considerable impact on movement and function. Lower limb sensory loss can contribute to problems with balance and mobility. Sensory loss to the upper limbs and hands can have a dramatic effect on dextrous, skilled hand movements for both perception and action.

Paraesthesia can often be hard for patients to describe, but common descriptions may be ‘pins and needles’ and ‘tingling’. If these sensations become uncomfortable, they can be termed ‘dysaesthesia’.

Mapping out the areas of paraesthesia or dysaesthesia can help pinpoint areas of nerve injury, particularly in the peripheral nervous system. There are common areas where a peripheral nerve can be compromised by direct impact or compression at either distal or proximal sites. Knowledge of the common areas where a peripheral nerve might be compromised is also helpful in diagnosis.

Injury or disease affecting peripheral and central nerves can lead to many forms of pain. Terms like neuralgia, neuropathic pain are used. Other terms that suggest nerve root involvement might include radicular pain or sciatica. If pain becomes chronic, the brain might maladapt and this may result in another cluster of symptoms controlling temperature, blood supply and sweating.

Weakness refers to reduced muscle strength. Assessment is done using Manual Muscle testing (MMT). Total weakness; paralysis which correlates with an MMT of 0 is denoted through use of the suffix -plegia while partial weakness is denoted using the suffix -paresis i.e.

Paraplegia – Total weakness of the lower limbs

Paraparesis – Weakness of the lower limbs short of complete weakness.

Both upper and lower motor neuron lesions will lead to weakness.

Secondary Complications

UMN or LMN weakness can quickly lead to structural changes within the muscle. Loss of sarcomeres can occur within hours and rapid muscle atrophy can take place. This shortening might become permanent and this leads to contractures.

Contracture can lead to unwanted biomechanical changes that can lead to musculoskeletal deformity and reduced function. Secondary complications can include joint capsule and ligament changes, pain and pressure area.

People with neurological conditions are faced with many barriers that make it difficult to remain physically active. This state on inactiveness will hurriedly lead to an increased risk of lifestyle diseases.

Exercises that focus on strength and cardiovascular fitness have therefore become an essential part of the neurological rehabilitation.

Due to weakness, the muscle pump is unable to function properly this leads to accumulation of fluid in the lower extremities.

Learned Non – use

Moderate to severe sensorimotor impairments of the upper and lower limb can quickly lead to a cascade of compensatory movement behaviors that favor use of the less affected limb with functions. This results in ‘learned nonuse’ of the hemiparetic extremity. Learned non-use behavior reduces the potential for recovery of the hemiparetic limb.

  1. Larner, A. J. (2011). A Dictionary of Neurological Signs (3rd). Liverpool, UK: Springer.
  1. Lennon, S., Ramdharry, G., & Verheyden, G. (2018). Physical Management for Neurological Conditions (4th). Elsevier.
  1. Ulrichsen, K. M., Kaufmann, T., Dørum, E. S., Kolskår, K. K., Richard, G., Alnæs, D., … & Nordvik, J. E. (2016). Clinical utility of mindfulness training in the treatment of fatigue after stroke, traumatic brain injury and multiple sclerosis: a systematic literature review and meta-analysis. Frontiers in psychology, 7, 912.
  1. Teodoro, T., Edwards, M. J., & Isaacs, J. D. (2018). A unifying theory for cognitive abnormalities in functional neurological disorders, fibromyalgia and chronic fatigue syndrome: systematic review. Journal of Neurology, Neurosurgery & Psychiatry, 89(12), 1308-1319.

References

  1. Larner, A. J. (2011). A Dictionary of Neurological Signs (3rd). Liverpool, UK: Springer.
  1. Lennon, S., Ramdharry, G., & Verheyden, G. (2018). Physical Management for Neurological Conditions (4th). Elsevier.
  1. Ulrichsen, K. M., Kaufmann, T., Dørum, E. S., Kolskår, K. K., Richard, G., Alnæs, D., … & Nordvik, J. E. (2016). Clinical utility of mindfulness training in the treatment of fatigue after stroke, traumatic brain injury and multiple sclerosis: a systematic literature review and meta-analysis. Frontiers in psychology, 7, 912.
  1. Teodoro, T., Edwards, M. J., & Isaacs, J. D. (2018). A unifying theory for cognitive abnormalities in functional neurological disorders, fibromyalgia and chronic fatigue syndrome: systematic review. Journal of Neurology, Neurosurgery & Psychiatry, 89(12), 1308-1319.