Neurological assessment

Chapter Five Neurological assessment






History


An assessment of the patient’s neurological function is made with every patient and during the taking of the patient’s history, decisions regarding the likelihood of neurological dysfunction will be made by all but the most inexperienced therapist. During the subjective examination, hypotheses regarding the patient’s primary dysfunction may be made following various models of clinical reasoning (Doody & McAteer, 2002). A process of clinical reasoning based on hypothetico-deductive reasoning and pattern recognition will enable the therapist to recognize, formulate and test likely hypotheses of dysfunction during both the subjective and the physical examinations. (See Chapter 3.)


The history has been described as the most important and most productive part of the neurological assessment, the purpose of which is to answer the questions ‘where is the lesion and what is it?’ and ‘is it one lesion or does the condition involve a system within the nervous system?’ Thus, in order to ensure high sensitivity and specificity to neurological dysfunction there are some techniques, commonly used by expert clinicians (King & Bithell, 1998), to make the subjective examination more valid. Development of an awareness of neurological time courses, patterns of presentation, and mechanisms of pain production should increase diagnostic confidence.



Pattern recognition


Thinking of the history of a neurological dysfunction as having a shape, with an onset, a rate of evolution to maximum deficit, and a time at maximum deficit, or a rate of continuing progression or recovery to the present state, is a helpful way of visualizing a pattern of symptoms (Fuller, 1993) (Fig. 5.1).



The physical neurological examination is traditionally structured into five components: assessing alterations in tone, muscle power, coordination, reflexes, and sensory perception (Perkin, 1992). A physical examination will elicit characteristic patterns of presentation from each component which, when combined with subjective information, will enable a clinical diagnosis to be made. Developing an appreciation of subjective patterns of presentation based on these five components should increase the validity of the subjective examination. Thus, by asking about perceptions of weakness (motor power), clumsiness (coordination), limb stiffness and shaking (tone), as well as pain, there will be a greater likelihood of identifying relevant dysfunction in the physical examination. Table 5.1 shows the features typical of two spinal conditions, cervical myelopathy and cervical radiculopathy, and highlights the subjective and physical characteristics of these upper and lower motor neuron lesions as an illustration of their distinguishable features.




Predominant symptom mechanism


The history should guide the therapist regarding the predominant mechanism of symptom production. In the case of pain, a sensitive and specific subjective examination will enable a hypothesis to be made regarding the predominant pain mechanism and thus whether a neurological examination is required. For example, if a patient has nociceptive ‘pinpoint’ pain in their cervical spine and no cues from their history to suggest neurological dysfunction, a neurological examination is not necessary. However, if the pain refers to the shoulder, a neurological examination would be indicated in order that possible radicular pain production and neural conduction loss could be evaluated. Thus, if the decision to conduct an examination is based on a pain mechanism model rather than on the extent of the referred pain, a more rational approach can be adopted. Whilst there is still some debate regarding the validity of the methods of identifying predominant pain mechanisms, the definitions of pain mechanisms are well accepted (Butler, 1995) (Table 5.2).


Table 5.2 Describing the main mechanisms of pain





















Pain mechanism Description
Peripheral nociceptive Local sources within muscles, joints and soft tissues
Peripheral neurogenic Sources in peripheral nerves, nerve roots and cranial nerves
Central Sources within neurons and synapses in the central nervous system
Efferent Pain related to efferent mechanisms, influenced by motor neurons including those of the autonomic nervous system
Affective Related to neurons and circuitry more concerned with the person’s affect



Central or peripheral nervous system lesion


Following a sensitive and specific subjective examination, the therapist should have, as well as a musculoskeletal primary hypothesis, a neurological primary hypothesis. One of the main aims of the physical neurological examination is to try to establish the location of a potential lesion(s). In a musculoskeletal setting, one of the primary aims of the neurological examination is to establish if the patient has a lesion of the CNS or PNS. Typically, manual therapists will encounter patients with predominantly PNS dysfunction and consequently will undertake an examination weighted towards identifying the dysfunction within that system. It is imperative that therapists ensure that potential CNS dysfunction has been screened for before a clinical diagnosis is made. Some of the cardinal features of PNS dysfunction, such as weakness, hyporeflexia and altered sensations can be elicited by CNS lesions and unless the possibility of CNS dysfunction is deliberately excluded there will be uncertainty regarding the validity of any subsequent clinical diagnosis. Within each component of the physical examination the extent of testing will be heavily influenced by the presence of CNS dysfunction.


Typically the physical examination is structured around assessment of tone, power, coordination, reflexes and finally sensation testing (Hawkes, 1996). One of the rationales for this order of testing relates to the need to expand the subsequent components of the examination in the presence of potential CNS dysfunction. For example, symptoms from the history and signs of altered tone and power would indicate an expansion of coordination, reflex and sensory testing components, whilst no such signs and symptoms would suggest only a screening reflex and sensory screen was indicated. This is a principle that applies throughout all the components of the physical examination.



Tone


The extent to which the examination of these systems is performed is governed by information obtained during the subjective examination. Assessments of tone, coordination and gait efficiency can be made as the patient enters the treatment area and during the course of the subjective examination, with more information being gained by observing the patient undressing and getting on and off the treatment couch.


Extrapyramidal disorders affecting the basal ganglia, such as Parkinson’s disease, lead to a more uniform increase in tone distributed amongst flexor and extensor muscle groups with muscular rigidity in trunk and limb muscles (Perkin, 1992). Tremor and involuntary movements are common with loss of speed in intricate movement such as finger-to-thumb opposition and during gait (Harrison, 1996). The rigidity, associated with extrapyramidal lesions, and the spasticity, associated with an upper motor neuron lesion (UMNL), can be reliably tested with two quick upper limb tests: wrist circumduction and the pronator catch test respectively (Donaghy, 1997). The wrist circumduction test involves gripping the patient’s wrist with one hand and repeatedly circumducting the hand, whilst the pronator catch test involves abruptly supinating the patient’s wrist and detecting a sudden jerk of resistance. If these signs are positive, an expansion of the examination of tone would be indicated, to include the lower limbs (Table 5.3).


Table 5.3 The expanded and contracted tone, coordination and reflex examination










Examination Test Rationale
Contracted

Sep 9, 2016 | Posted by in MANUAL THERAPIST | Comments Off on Neurological assessment
Premium Wordpress Themes by UFO Themes