4 Western medical acupuncture in neurological conditions
Application of acupuncture in neurological conditions
Presenting symptoms may be broadly categorized as: (1) sensory symptoms; (2) motor symptoms; (3) visceral symptoms; and (4) generalized symptoms such as mood disturbance. The development of clearly reasoned treatments for patients based on Western science requires some understanding of these presentations and an awareness of current literature. This chapter will explore these presentations and consider possible treatment options, including acupuncture.
Basic mechanisms of action of acupuncture
White et al. [1] have clearly summarized the main mechanisms underlying the effects of acupuncture. These include: (1) local effects; (2) segmental effects; (3) extrasegmental and central regulatory effects; and (4) effects relating to myofascial trigger points.
Part 1 Sensory function
Absent or impaired sensation
Damage to sensory pathways within the nervous system may lead to impairments in sensation. The degree of impairment will depend on the site and extent of the lesion. Sensation and proprioceptive deficits may lead to considerable difficulties with balance and mobility as well as functioning of the upper limbs [2]. The loss of sensory information due to lesions within the pathways has a substantial effect on cortical responsiveness and topographical organization of the primary sensory cortex [3].
Prevalence of impaired sensation in neurological conditions
Sensory deficits are common in neurological conditions, with an estimated prevalence of up to 65% in stroke [4], 80–90% of those with multiple sclerosis [5] and most individuals with spinal cord injury. Sensory features are also prominent in peripheral neuropathies involving the sensory nerves, such as alcoholic peripheral neuropathy and the acute motor and sensory axonal neuropathy subtype of Guillain–Barré syndrome [6, 7].
Acupuncture for impaired sensation
We are unaware of any studies specifically using acupuncture to improve sensation, although studies by Napadow et al. [8] indicate that modifications of the primary sensory cortex may be induced by acupuncture. Many studies in neurorehabilitation have used various types of sensory stimulation, but these usually measure the outcome in terms of improved motor function rather than commenting on sensory function [9]. Perhaps this is an area that merits further exploration.
Abnormal sensations, including paraesthesia and pain
Pain is common and problematic in neurological conditions (Table 4.1). Effective management is needed and acupuncture may be of value in this situation. It is important to understand the nature of the pain presentation to guide acupuncture intervention and expected outcomes.
Table 4.1 Prevalence of pain in common neurological conditions
| Condition | Nociceptive pain | Neuropathic pain |
|---|---|---|
| Stroke | No data | |
| Traumatic brain injury | ||
| Parkinson’s disease | Up to 70% | 10% |
| Cerebral palsy (adult) | 82% | No data |
| Multiple sclerosis | No data | 28% |
| Spinal cord injury | Up to 41% | |
| Guillain–Barré syndrome | 55% (acute phase) | 28–49% |
References: MacGowan et al. (147); Moulin et al. (148); Weimar et al. (149); Siddall et al. (150); Jahnsen et al. (151); Kogos et al. (152); Nampiaparampil (153); Ruts et al. (154); Beiske et al. (155); Osterberg & Boivie (5).
Is the pain nociceptive or neuropathic?
‘Nociceptive pain’ refers to pain which results from activation of nociceptors in the tissues, for example by injury, inflammation, ischaemia or degeneration [10]. It is commonly described as dull or aching and may affect the musculoskeletal system or the viscera. This type of pain is very common and often responds well to simple interventions such as analgesics, exercise, transcutaneous electrical nerve stimulation (TENS) or acupuncture (Tables 4.2 and 4.3).
Table 4.2 Definitions of nociceptive and neuropathic pain
| Type of Pain | IASP* Definition, 2008 | Subdivisions of pain |
|---|---|---|
| Nociceptive pain | Pain arising from stimulation of nociceptors | |
| Neuropathic pain | Pain arising as a direct consequence of a lesion or disease affecting the somatosensory system | |
* IASP, International Association for the Study of Pain.10
Table 4.3 Clinical examples of nociceptive and neuropathic pain
‘Neuropathic pain’ refers to pain which arises as a direct consequence of a lesion or disease affecting the somatosensory system [10]. As such it is common in neurological conditions. This type of pain may develop spontaneously or may be evoked by various stimuli, which are normally innocuous. It is commonly described as burning, shooting, pricking or throbbing. Neuropathic pain may affect the peripheral or central neural pathways (Tables 4.2 and 4.3). It is challenging to treat and may require the use of medications such as amitriptyline or gabapentin, psychological therapies such as cognitive-behavioural therapy and physiotherapy [11]. Refractory cases may require consideration for spinal cord stimulation or deep brain stimulation.
Mechanisms of neuropathic pain in neurological conditions
Peripheral neuropathy
Peripheral focal or generalized neuropathies involve loss of myelin and/or axonal damage of peripheral nerves. Neuropathic pain may arise from molecular changes in the area of injured or degenerating axons [12]. Hypersensitivity in the peripheral nervous system will then drive the development of hypersensitivity in the spinal cord and central pain transmission pathways.
Stroke, traumatic brain injury, spinal cord injury, multiple sclerosis
In stroke, traumatic brain injury, spinal cord injury and multiple sclerosis functional impairment of the spinothalamocortical tract conveying pain and temperature sensation from the periphery to the cortex seems crucially important in the development of neuropathic pain [5, 13–15]. In spinal cord injury evidence suggests that those individuals with more extensive reorganization of the primary somatosensory cortex experience more severe ongoing pain [16].
Parkinson’s disease
The disturbance of central processing of nociceptive information by the basal ganglia is likely to have a role in the development of central neuropathic pain in Parkinson’s disease [17, 18]. In addition dysfunction of nociceptive processing at spinal cord level is also involved [19].
Evidence for use of acupuncture for pain in neurological conditions
Peripheral neuropathy
Studies have evaluated the use of acupuncture for peripheral neuropathy of various aetiologies (Table 4.4). These reveal some positive results, particularly the finding that acupuncture improved nerve conduction in tibial and sural nerves [20]. Further prospective research is needed.
Spinal cord injury
Studies in spinal cord injury are small. They provide hints that acupuncture may be useful for nociceptive and neuropathic pain (Table 4.5).
Multiple sclerosis
No large-scale trials have been conducted. Descriptive case reports suggest benefit from electroacupuncture at 50 Hz for painful trigeminal neuralgia [21], as well as body and ear acupuncture for leg pain and dysaesthesia affecting the hands [22, 23].
Stroke, traumatic brain injury, Parkinson’s disease and adult cerebral palsy
Descriptive case reports indicate benefits from acupuncture for central neuropathic pain in stroke [24], for nociceptive shoulder pain in stroke [25] and for central neuropathic pain in traumatic brain injury [26]. Implanted percutaneous electrical nerve stimulation (PENS) reduced chronic hemiplegic shoulder pain [27]. No large-scale studies have been conducted.
Paraesthesia and dysaesthesia
At this point it is worth mentioning abnormal sensations which are commonly reported in neurological conditions. ‘Paraesthesia’ refers to abnormal sensations which are not described as unpleasant [28]. This may include sensations such as tingling, prickling, pins and needles, burning, aching and tightness. ‘Dysaesthesia’ is defined as an unpleasant abnormal sensation and includes the more specific categories of allodynia and hyperalgesia. It is therefore included in the category of neuropathic pain [28]. Paraesthesia and dysaesthesia may represent a pure sensory phenomenon such as in cortical strokes affecting the postcentral gyrus, or may be accompanied by motor signs such as tonic spasms in multiple sclerosis [29, 30]. Paraesthesia and dysaesthesia may be spontaneous or evoked. They arise from abnormal activity in the nervous system such as ectopic impulse activity in the central or peripheral nerves, or ephaptic transmission between physically adjacent neurones in areas of demyelination [31]. These sensations cause substantial distress to some individuals. Management of these sensations follows the recommendations for neuropathic pain.
Acupuncture for paraesthesia and dysaesthesia
Carpal tunnel syndrome is an entrapment neuropathy of the median nerve causing paraesthesia and pain. Napadow [8, 32] reported improvements in these symptoms following a course of acupuncture (Table 4.6). Functional magnetic resonance imaging indicated changes in cortical representation as well as reduced activation of the limbic system. These changes accompanied reports of improvement from the patients. It may also be worth attempting needling with patients with dysaesthesia from central sensory lesions. No research has been conducted on this population.
Part 2 Motor function
Weakness and paralysis
Acupuncture for weakness and paralysis
Many studies have assessed the impact of acupuncture on motor recovery in stroke. Fewer studies have assessed weakness in other populations (Table 4.7).
These studies suggest some benefits from a range of interventions, including body, ear and scalp acupuncture, as well as in combination with a strengthening programme. However these studies also raise questions about acupuncture study design, particularly regarding the upper limb. None of the acupuncture studies assessing arm function in stroke had exclusion criteria according to motor ability in the fingers or wrist. Research indicates that the ability to extend the fingers is a powerful prognostic factor for eventual arm function in stroke [33]. Other studies stipulate this ability as minimal entry level to studies, for example in constraint-induced movement therapy [34]. Interestingly, in Liu’s study [35], those individuals with some active finger extension before the acupuncture intervention gained an additional 30° with combined acupuncture and strength training. Design of studies with more defined entry criteria might provide useful information about the effects of acupuncture for motor recovery in specific subpopulations.
Spasticity
Spasticity is a movement disorder observed in individuals with lesions of the upper motor neurone pathways, for example, in stroke, multiple sclerosis or spinal cord injury. Spasticity is classically defined as a motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes [36]. It is accompanied by a range of other features such as weakness and loss of dexterity [37]. The neurophysiology of spasticity is complex but involves abnormalities in proprioceptive, cutaneous and nociceptive reflexes. Persistent spasticity may lead to adaptive changes such as soft-tissue contracture. The impact of spasticity on functional ability is unclear but for many individuals spasticity is problematic [38].
Prevalence of spasticity
The prevalence of spasticity varies according to condition, with over 90% of those with cerebral palsy [39], 84% of people with multiple sclerosis [40], 65–78% of people with spinal cord injury [41] but only around 17% of people with stroke presenting with spasticity [42]. Some people with traumatic brain injury develop severe and chronic spasticity but prevalence figures are not reported [43].
Management of spasticity
Related posts:
Practical application of Western medical acupuncture in neurological conditions
Peripheral nervous system disorders
Current context: neurological rehabilitation and neurological physiotherapy
History and background of traditional Chinese medicine in neurological conditions
Pulling it together
Acquired brain injury: stroke, cerebral palsy and traumatic brain injury
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