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Biomedical subjects

Yair Sharav

Publications and source records attributed to Yair Sharav.

12 recordsLinked to original sources
PubMed2006

Focused hypnotic analgesia: local and remote effects.

Suggestion for hypnotic analgesia aimed at a specific body area is termed "focused hypnotic analgesia". It is not clear, however, whether this analgesia is limited to a specific body location or spread all over the body. Focused hypnotic analgesia was studied, in response to ascending electrical stimuli, when analgesia and stimulation were applied to the same area (local), and when analgesia was applied to one location and stimulation was delivered to a different area (remote). The face or leg served alternately as the local or remote areas, and the effect was tested in 12 high-hypnotizable (HH) and 13 low-hypnotizable (LH) subjects. Hypnotic analgesia in the local site produced a significant pain reduction compared to the remote site in HH subjects (P<0.0001) but not in LH subjects (P=0.68). As stimuli increased in intensity the reduction in pain as a result of hypnosis was larger both in HH and LH subjects (P<0.0001). Nevertheless, significant analgesia occurred in the 3 highest intensities in the local and remote location of HH subjects, but only in 2 highest intensities in the local and 1 in the remote of LH subjects. We conclude that in HH subjects focused hypnotic analgesia is mostly confined to the area aimed at, but some spread of analgesia to remote areas cannot be dismissed all together. Alternatively, this "spread" of analgesia could be due to a placebo effect in the remote area. Focused hypnotic analgesia requires increased attention to the body area aimed at, unlike analgesia achieved by distraction of attention.

Adult↗
PubMed2005

Jaw clenching modulates sensory perception in high- but not in low-hypnotizable subjects.

AIMS: To investigate the effect of jaw clenching on the sensations evoked at segmental and nonsegmental levels by painful and nonpainful stimuli and in relation to hypnotic susceptibility. METHODS: The effect of jaw clenching on painful and nonpainful sensations on the face and leg was studied in high-hypnotizable (HH) and low-hypnotizable (LH) subjects. Sixteen healthy subjects were selected and assigned to either the HH group (n = 8) or the LH group (n = 8). Painful and nonpainful electrical stimuli were delivered in random order to the face and leg. The subjects rated the intensity of the evoked sensation on a visual analog scale (VAS) while clenching or not clenching their jaw. RESULTS: Jaw clenching significantly attenuated the VAS sensory ratings of all the subjects under various conditions (F(1-31) = 6.15, P < .02). When the HH and LH subjects were analyzed separately, jaw clenching was found to be effective in reducing sensations only in the HH subjects (F(1-15) = 8.30, P = .01), only those evoked in the face (segmental level), and only those evoked by nonpainful stimuli (tied Z = 2.52, tied P < .02). CONCLUSION: Sensory modulation produced by jaw clenching may be related to hypnotic susceptibility. On the whole, jaw clenching had a weak, local effect in modulating sensation, in contrast to its known widespread effect on motor behavior.

Adult↗
PubMed2004

Focused analgesia and generalized relaxation produce differential hypnotic analgesia in response to ascending stimulus intensity.

This study was designed in order to examine the effects of different types of hypnotic suggestion on hypnotic analgesia. Generalized relaxation and focused analgesia were induced in seven high-hypnotizable (HH) and eight low-hypnotizable (LH) subjects. Subjects were not aware to which group they belonged. The two groups did not differ in their expectation rates to achieve analgesia under hypnosis. Pain intensity and unpleasantness were rated on visual analogue scales in response to painful electrical stimuli, delivered in random order in five ascending intensities. Both focused analgesia and generalized relaxation decreased pain intensity significantly (P < 0.01). However, stimulus-intensity response curves differed under the two hypnotic conditions. As stimulus intensity became higher pain reduction was enhanced under focused analgesia, while a constant reduction occurred under generalized relaxation. The interaction between hypnotic state and stimulus intensity was significant for focused analgesia (P < 0.05) but not for generalized relaxation (P > 0.07), difference became more pronounced when analyzed for HH subjects only (P < 0.002 for analgesia, P > 0.10 for relaxation). Pain reduction was significantly higher in HH than in LH subjects under focused analgesia (P < 0.02) but not under generalized relaxation (P > 0.5). We conclude that by utilizing two modes of hypnotic suggestions in response to ascending stimuli, we were able to discover two components of hypnotic analgesia. One shows a parallel shift in the stimulus-response function, has features similar to placebo and bears no clear relationship to hypnotic susceptibility. The other shows a slope change in the stimulus-response curve and has a positive relationship to hypnotic susceptibility.

Adult↗
PubMed2003

Management of chronic orofacial pain: today and tomorrow.

In the facial region, chronic pain syndromes include musculoskeletal pain, neuropathic disorders, vascular pain, and other chronic headaches. Therapy of chronic facial pain syndromes often relies on long-term psychotropic medications that cause severe side effects and offer nontotal pain relief. In this article, therapeutically relevant advances in science, which will change the approach to pain management, are reviewed. Understanding the mechanisms involved in chronic pain enables the clinician to skillfully apply this knowledge when selecting a therapy.

Afferent Pathways↗
PubMed2002

Hemicrania continua.

Unilateral throbbing headaches may present similar signs and symptoms as dental pathology and are a diagnostic challenge for dental practitioners. Cases may be seen with a primary complaint of unilateral pain or referred by medical colleagues for exclusion of dental causes. In the present article the authors add a new case of hemicrania continua (HC), which is one such unilateral headache, and review the previously published cases. HC is relatively easy to treat since it responds completely to treatment with indomethacin. However, as is presented in this case, HC may masquerade as dental pain. Cases secondary to trauma, systemic disease, and nervous system pathology have been described in the literature, and the clinician must exclude these possible causes. A thorough knowledge of this entity is therefore essential.

Adult↗
PubMed1989

Autotomy behavior in rats following peripheral deafferentation is suppressed by daily injections of amitriptyline, diazepam and saline.

Amitriptyline, a tricyclic antidepressant (TCA), was effective in suppressing self-mutilation of a peripherally deafferented hind paw in rats ('autotomy'). This effect was not due to the drug's sedative effect, since locomotor activity was not lower in treated than untreated rats. Daily injections of normal saline also suppressed autotomy, but for a shorter period of time than amitriptyline. This effect was not apparent in diazepam-treated rats, suggesting that the saline injection delayed autotomy as a result of stress-induced anti-nociception. Since amitriptyline is effective in humans in alleviating certain chronic pain disorders, these results further corroborate the suggestion that autotomy is a model of chronic pain, sensitive to centrally acting analgesics and to some forms of stress.

Amitriptyline↗
PubMed1987

The analgesic effect of amitriptyline on chronic facial pain.

The efficacy of amitriptyline was evaluated in 28 patients with chronic oral-facial pain. Most of the patients had evidence of musculoskeletal pain while some had a history suggesting pain of neurogenic origin. Two patients had mixed elements of neurogenic and musculoskeletal pain. Amitriptyline was more effective than placebo in reducing pain after 4 weeks of treatment. No effect was found after only 1 week of drug administration in either dose range. When the patients were divided into depressed and non-depressed groups based on their Hamilton depression scores, amitriptyline reduced pain in the depressed and in the non-depressed groups as compared to placebo. Amitriptyline reduced the depression scores in the depressed group but had no effect on the depression scores in the non-depressed group. Thus, pain reduction was not associated with a change in mood in the non-depressed group. Amitriptyline had no effect on patients' ratings of the intensity of experimental heat stimuli. We conclude that amitriptyline is effective in the treatment of chronic oral-facial pain and that its efficacy is independent of its effects on depression. It appears that tricyclic antidepressants act in a fashion different from opiate drugs that alter the sensory discriminative component of pain.

Adult↗
PubMed1981

Masseter inhibitory periods and sensations evoked by electrical tooth pulp stimulation.

The masseter inhibitory period and sensations evoked by electrical tooth pulp stimulation were assessed in 30 human subjects. Five intensities of electrical stimuli, producing sensations varying from below sensory detection threshold to suprathreshold pain, were applied to upper central incisors. At each stimulus intensity a train of 30, 1-msec, cathodal pulses with an interpulse interval of 2 sec was applied. The averaged masseter activity evoked by the 30 pulses at a fixed stimulus intensity was compared to the quality of the sensation elicited. The threshold for the masseter inhibitory period coincided approximately with an individual's detection threshold for the tooth pulp stimulation. Three configurations of masseter inhibitory periods (single, double and merged) were produced by different stimulus intensities. However, no particular configuration was associated unequivocally with pain sensation. Increases in stimulus intensity evoked changes both in the configuration of the masseter inhibitory period and in the quality of the sensation produced. Chi square analyses showed significant, but progressively weaker, associations between: (1) masseter inhibitory period configuration and stimulus intensity; (2) quality of sensation and stimulus intensity; and (3) quality of sensation and masseter inhibitory period configuration. The weakness of the association between the quality of sensation and masseter inhibitory period configuration also was demonstrated in a double-blind study of the effects of a narcotic analgesic, fentanyl. Although the strengths of non-pain and pain sensations were reduced significantly after fentanyl, there were no changes in the masseter inhibitory periods.

Adolescent↗