Biomedical subjects
D Bowsher
Publications and source records attributed to D Bowsher.
Central pain: clinical and physiological characteristics.
OBJECTIVES: To study the clinical and pathophysiological features of central pain due to damage to the CNS. METHODS: 156 patients (mostly with ischaemic strokes, some with infarct after subarachnoid haemorrhage and other cerebral conditions; one with bulbar and others with spinal pathology) with central pain have been investigated clinically and varying numbers instrumentally with respect to quantitative somatosensory perception thresholds and autonomic function. RESULTS: Pain onset was immediate in a minority; and from a week or two up to six years in > 60%. For those with supraspinal ischaemic lesions, the median age of onset was 59; dominant and non-dominant sides were equally affected. Two thirds of the patients had allodynia, including a previously undescribed movement allodynia apparently triggered from group I afferents. Most patients exhibited autonomic instability in that their pain was increased by physical and emotional stress and alleviated by relaxation; cutaneous blood flow and sweating may also be affected. Pain occurred within a larger area of differential sensory deficit. The critical deficit seems to be for thermal and pinprick sensations, which were more pronounced in areas of greatest than in areas of least pain; whereas low threshold mechanoceptive functions, if affected, did not vary between areas of greatest and least pain. Skinfold pinch (tissue damage) pain thresholds were only slightly affected in supraspinal cases, but greatly increased in patients with spinal lesions; thermal (heat) pain did not show this dissociation. CONCLUSION: The pathogenetic hypothesis which seems best to fit the findings is that there is up regulation or down regulation of receptors for transmitters, possibly mainly noradrenergic, over time.
The management of central post-stroke pain.
Central post-stroke pain (CPSP) used to be known as 'thalamic syndrome'. Early post-mortem studies showed that many cases had extrathalamic lesions, and modern imaging methods have confirmed and extended these findings. CPSP affects between 2 and 6% of stroke patients, ie, there is an annual incidence in the UK of between 2000 and 6000. Most patients with CPSP appear to be younger than the general stroke population, and usually to have relatively mild motor affliction; thus they may live for many years, giving a prevalence perhaps as high as 20,000. True CPSP, characterised by a partial or total deficit for thermal and/or sharpness sensations, is best treated initially with adrenergically active antidepressants. If these do not work, mexiletine may be added in suitable cases. Recent studies suggest that stimulation of the motor cortex or spinal cord by implanted electrodes may help patients resistant to medical treatment. Positive relaxation, as an adjuvant therapy, should be used in nearly all cases. Considerable or even total relief can be achieved in almost two thirds of patients. There is evidence that the sooner antidepressant treatment is begun, the more likely the patient is to respond; time should not be wasted trying conventional analgesics, which rarely have any significant effect.
Pathophysiology of postherpetic neuralgia: towards a rational treatment.
Explore the source record for details and available documents.
Neurogenic pain.
Explore the source record for details and available documents.
Post-herpetic neuralgia in older patients. Incidence and optimal treatment.
Post-herpetic neuralgia (PHN) is a disease caused by having had herpes zoster; it is not a continuation of shingles. Up to 50% of elderly patients who have had shingles may develop PHN. PHN is defined as pain recurring or continuing at the site of shingles, 1 or more months after the onset of the rash. Because many cases resolve spontaneously in the early stages, no claims of 'pharmacological cure' can be entertained before 3 months post-rash. In fact, some authorities will not accept claims made before 6 months. Antivirals administered systemically within the appropriate time-window greatly relieve the pain of acute shingles, and to a large extent prevent scarring. There is no evidence that they prevent the subsequent development of PHN. However, patients with PHN whose acute shingles were treated with aciclovir obtain pain relief with antidepressants in half the time required by those patients who did not receive aciclovir for their acute shingles. If patients with acute shingles are given low dose amitriptyline from the onset, only half as many are in pain at 6 months as a group not so treated, irrespective of the antiviral treatments given. The most effective treatment of established PHN to date consists of adrenergically active antidepressants. There is a strict correlation with the brevity of the interval between acute shingles and initiation of such treatment. 75% of patients starting treatment with antidepressants within 3 to 6 months after shingles obtain pain relief, whereas if antidepressants are not started for 2 years, only 25% obtain pain relief.(ABSTRACT TRUNCATED AT 250 WORDS)
The cost of treatment for post-herpetic neuralgia in the UK.
Post-herpetic neuralgia (PHN) following acute shingles caused by the herpes simplex virus is a painful and often disabling condition. Treatment of the condition can involve a range of drug therapies. In addition, patients with continuing pain may make several visits to general practitioners and hospital outpatient departments. The costs of treatment for these patients may be substantial. The main objective of this study was to estimate the costs and consequences to the UK National Health Service (NHS) of the treatment of PHN following shingles, and the effect of the condition on patients' lives in terms of pain and time off usual activities such as work. The lifetime direct treatment costs of a cohort of people from onset of PHN to resolution of the disease or death were calculated. These costs were estimated from data on the type and quantity of health resources used, and the unit costs or prices of those resources. This study has shown that PHN can be a costly consequence of acute shingles. For patients attending a tertiary referral centre the lifetime cost was 770 British pounds sterling. For a 1-year incidence cohort of people with shingles in the UK, the lifetime costs of treating PHN are between 4.8 million British pounds sterling (incidence of 21 000 people) and 17.9 million British pounds sterling (incidence of 78 200 people). Efforts are needed to reduce the incidence or severity of PHN.(ABSTRACT TRUNCATED AT 250 WORDS)
Percutaneous cervical cordotomy: a review of 181 operations on 146 patients with a study on the location of "pain fibers" in the C-2 spinal cord segment of 29 cases.
The authors present a review of 146 patients who underwent 181 percutaneous cervical cordotomies for intractable pain. In addition, an anatomical-clinical correlation was carried out for 29 of these patients. It was found that the fibers subserving pain sensation in the C-2 segment lie in the anterolateral funiculus between the level of the denticulate ligament and a line drawn perpendicularly from the medial angle of the ventral gray-matter horn to the surface of the cord. The best analgesic results have been obtained by creating lesions that extend 5.0 mm deep to the surface of the cord and destroy about 20% of the hemicord. There is a somatotopic organization with sacral fibers running ventromedially and cervical fibers running dorsolaterally. The authors believe that the ascending fibers subserving the distinct sensations of pain induced by tissue damage and pinprick, although mixed (overlapping) in the anterolateral funiculus of the spinal cord, are physiologically distinct from one another. Whereas some cordotomies, both in the current series and as reported in the literature, may affect these functions differentially, optimum pain relief seems to be obtained only when pinprick sensation is also abolished in the affected segments. Evoked pain sensation is not abolished by cordotomy, but its threshold is greatly raised. When pathological pain is completely abolished, so is pinprick sensation. However, in a number of cases where pathological pain was only partially alleviated, pinprick sensation remained intact. The significance of these and other cases reported in the literature is discussed. The importance of clinically distinguishing between pain caused by tissue damage and pinprick sensation is emphasized, as well as that between return of pre-existing or new tissue-damage pain and painful dysesthesia.
Sensory consequences of stroke.
Explore the source record for details and available documents.
Pain syndromes and their treatment.
Neurogenic pain (encompassing all types of neuropathic and central pain) is discussed. Experimental work is presented in a model in which the rat sciatic nerve is loosely ligatured. In painful human neuropathies, tricyclic antidepressants have been found to be effective in proportion to the degree they facilitate monoaminergic activity. Several papers also stress the importance of early treatment with amitriptyline or desipramine, and the ineffectiveness of analgesics, including narcotics. In nociceptive pain, recent findings in humans emphasize the importance of both the retroinsular (SII) and the anterior cingulate cortices in the conscious appreciation of pain. Opioid studies have revealed individual differences in the metabolism of morphine to its 3- and 6-glucuronosides; patients with nociceptive pain who respond poorly to morphine or diamorphine probably have a high 3:6 ratio. It has been pointed out that methadone may be useful in such cases, as it is not broken down to glucuronosides.
Responsiveness of chronic pain to morphine.
Explore the source record for details and available documents.
CSF enkephalins in diabetic neuropathy.
CSF methionine and leucine enkephalins were measured by high performance liquid chromatography and radioimmunoassay in diabetic patients with painful neuropathy (n = 22) and painless neuropathy (n = 5), and non-diabetic subjects with low back pain (n = 11). Wide variations in CSF enkephalin levels were found and they were often below the limit of detection (less than 0.1 pmol/l) in the diabetic and non-diabetic groups. The origin of CSF enkephalins is unknown and CSF levels may not reflect tissue concentrations. In conclusion, CSF enkephalin levels are difficult to interpret and do not provide useful information on the function of enkephalinergic pathways.
Weighted needle pinprick sensory thresholds: a simple test of sensory function in diabetic peripheral neuropathy.
A simple device is described, consisting of 12 weighted 23 gauge disposable needles (0.2 to 5.2 g), for testing sensation in busy diabetic clinics. The pinprick sensory threshold (PPT) is the lightest weighted needle which consistently elicits a sharp sensation. The subjects were 48 healthy controls (hospital staff), 44 diabetic patients without neuropathic symptoms, and 35 diabetic patients with chronic painful neuropathy. In the controls, the mean PPT from the right hand and foot obtained on two test occasions a week apart did not differ significantly. In diabetic patients without symptomatic neuropathy, the mean PPT in the right hand and right foot were significantly higher than in the controls. The diabetic patients with painful neuropathy had clearly increased mean PPT in the right hand and foot compared with controls. Marstock thermal limen in diabetic patients with painful neuropathy correlated significantly with PPT determinations. PPT and thermal thresholds probably give comparable information on small fibre dysfunction in diabetic patients with symptomatic neuropathy. Compared with thermal threshold determinations however, the weighted needle apparatus is inexpensive, simple, and rapid to use.
The location and function of respiratory fibres in the second cervical spinal cord segment: respiratory dysfunction syndrome after cervical cordotomy.
After high cervical percutaneous cordotomy for pain in malignant disease, 12 patients died during sleep at postoperative intervals between 1 and 8 days. Nine died after a first cordotomy and three after a second (contralateral) procedure. All except one had known pulmonary disease before operation. The operated segment of the spinal cord (C2) was studied histologically after death. Superposition of lesion outlines made it possible to determine those parts of the lesioned areas common to all unilateral and bilateral cases respectively. All cases dying of presumed respiratory dysfunction syndrome had lesions involving the region of the anterolateral funiculus in the C2 segment containing "pain" fibres activated from the second to fifth thoracic dermatomes. The fibres whose destruction appeared to be responsible for respiratory dysfunction syndrome were completely intermingled with ascending "pain" fibres. The possibility of these fibres being afferent in function is discussed.
Disturbances of C-fibre-mediated sensibility in lumbosacral disc disease.
Explore the source record for details and available documents.
Acute herpes zoster and postherpetic neuralgia: effects of acyclovir and outcome of treatment with amitriptyline.
This retrospective study was designed to assess the effects of acyclovir treatment of acute herpes zoster on subsequent postherpetic neuralgia, and to examine the effects of amitriptyline in the treatment of postherpetic neuralgia. Eighty seven patients with postherpetic neuralgia of three or more months' duration were studied: 24 of them had had their herpes zoster treated with oral acyclovir. At first presentation, only 25% of the 24 patients who had had their herpes zoster treated with acyclovir selected the word group containing burning on the McGill pain questionnaire compared with 76% of the 63 patients who had not received acyclovir. A higher proportion of patients who had had acyclovir than had not selected the word group which contains the word aching (63% versus 49%). Acyclovir thus appears to change the nature of postherpetic neuralgia. Postherpetic neuralgia was treated with amitriptyline, alone or in combination with distigmine and/or sodium valproate. There was a strong correlation between pain relief and the interval between the occurrence of herpes zoster and the initiation of treatment with amitriptyline--early treatment is almost twice as likely to be successful as late. Since conventional analgesics and sympatholytic drugs are of no benefit in the treatment of established postherpetic neuralgia, the sequelae of herpes zoster must, therefore, be recognized and treated with amitriptyline as soon as possible.