Brush Allodynia Research Articles

The First 5 Minutes After Greater Occipital Nerve Block

We performed greater occipital nerve blocks on 24 migraineurs with unilateral migraine and trigeminal nerve distribution allodynia. Using a visual analog scale for migraine pain, brush allodynia in the trigeminal nerve distribution and photophobia were reduced 64%, 75%, and 67%, respectively, after 5 minutes. Allodynia improved faster than headache. The results of this study suggest that greater occipital nerve blocks initiate an inhibitory process that shuts down several symptom generators.

Dihydroergotamine for Early and Late Treatment of Migraine With Cutaneous Allodynia: An Open‐Label Pilot Trial

To explore whether dihydroergotamine (D.H.E. 45) is equally effective and safe for migraine with allodynia, when administered either early or late in an attack. Central sensitization may account for the extracranial tenderness and cutaneous allodynia that can occur with migraine. Once allodynia is established, triptans are less effective. Dihydroergotamine is often effective for patients whose refractory headaches have failed prior triptan therapy. In this single-center, open-label pilot trial, patients with episodic migraine associated with cutaneous allodynia were treated on 2 occasions with dihydroergotamine 1.0 mg intramuscularly. One attack was treated within 2 hours (early) and a second attack at 4 hours (late) after the onset of throbbing pain. Headache pain and any associated symptoms, subjective cutaneous allodynia, and mechanical (brush) allodynia were assessed. All data were analyzed using the Fisher's exact test. Thirteen patients met the entry criteria; however, data from only 9 patients, those who completed treatment for 2 migraine attacks, were used to evaluate the efficacy and safety of dihydroergotamine. Whether they took dihydroergotamine early or late in the attack, most patients (>55%) had headache relief within 2 hours, and at least 44% of patients achieved headache-free status by 8 hours postdose. Subjective cutaneous allodynia started to decline after 30 minutes postdose in the early treated group and after 120 minutes postdose in the late-treated group. Brush allodynia began to decline after 15 minutes postdose in the early treated group and after 90 minutes postdose in the late-treated group. Six of 9 patients (67%) reported at least 1 adverse event. The results of this pilot trial provide proof of concept for the headache-relief benefit of dihydroergotamine in patients with migraine headache and allodynia. A large, placebo-controlled trial of dihydroergotamine in allodynic patients is warranted.

Identifying Cutaneous Allodynia in Chronic Migraine Using a Practical Clinical Method

Cutaneous allodynia is common in migraine. In the majority of previous studies on allodynia in migraine, only patients with episodic migraine (EM) were included. Little is known on patterns of allodynia in chronic migraine (CM). Since the presence of allodynia is associated with a poor response to triptans, a clinically practical method to test migraine patients for allodynia would be useful to the clinician. The aim of this study was to assess the prevalence of dynamic mechanical (brush) allodynia (BA) in CM, using a clinically practical method. Eighty-nine CM patients were prospectively recruited. Patients were given a structured questionnaire regarding demographic data and migraine characteristics. Allodynia was tested using a 10 x 10-cm gauze pad to brush various areas of the skin lightly. The prevalence of BA in the entire study population and in different patient subgroups was calculated. BA was present in 42.7% (38/89) of the patients. The presence of allodynia was unrelated to age, disease duration or to the occurrence of an acute headache exacerbation at the time of testing. Allodynia was positively associated with a history of migraine aura. BA was most common in the cephalic area, but was also seen in cervical dermatomes. BA is common in CM and, unlike in EM, is not significantly affected by the occurrence of an acute headache exacerbation. This suggests that central trigeminovascular neurons are chronically sensitized in patients experiencing migraine headache >15 days per month. The testing of BA in the clinical setting is possible using a simple and brief approach. It allows the clinician to determine whether the patient is sensitized, a diagnosis that affects treatment decisions.

Comparison of Dynamic (Brush) and Static (Pressure) Mechanical Allodynia in Migraine

Allodynia has been described in migraine but has not been fully investigated for the different sensory modalities. The aim of this study was to compare the prevalence of dynamic (brush) and static (pressure) mechanical allodynia in migraine patients and to suggest a practical method of testing them in a clinical setting. Patients with International Headache Society-defined episodic migraine (EM) or with transformed migraine (TM) as defined by Silberstein and Lipton were prospectively recruited from the Jefferson Headache Center out-patient clinic. A questionnaire of migraine features and symptoms of allodynia was administered. Brush allodynia (BA) was tested by cutaneous stimulation with a gauze pad and pressure allodynia (PA) was tested using von Frey hairs (VFH). The prevalence of BA and PA in all patients and in the different subgroups was calculated and correlated with migraine features. We recruited 55 migraine patients. Twenty-five had EM and 30 had TM. BA was present in 18 (32.7%) patients and PA in 18-24 (32.7-43.6%). Allodynia to both brush and pressure was found in 13-17 (23.6-30.9%) patients. If a patient had allodynia to one modality only, it was more likely to be PA than BA. Both BA and PA were more common in patients with TM compared with those with EM [BA 46.7% vs. 16.0%; PA (differences significant for the medium and thick VFHs) 50% vs. 20% and 50% vs. 12%, respectively]. Both types of allodynia were also more common in patients with migraine with aura compared with those with migraine without aura (BA 57.1% vs. 17.6%; PA 57.1-61.9% vs. 17.6-32.7%). There was a positive correlation between allodynia score (as obtained by examination) and allodynia index (as obtained by history) for both BA and PA. The incomplete, although considerable, overlap between BA and PA suggests that allodynia to different sensory modalities is associated with sensitization of different neuronal populations. Because PA was more common than BA, it may be a more sensitive indicator of allodynia in migraine. PA can be tested clinically in a practical and systematic manner.

The Effects of Greater Occipital Nerve Block and Trigger Point Injection on Brush Allodynia and Pain in Migraine

The Effects of Greater Occipital Nerve Block and Trigger Point Injection on Brush Allodynia and Pain in Migraine

Brush Allodynia in Hospitalized Headache Patients

To describe the incidence and time course of dynamic mechanical allodynia (brush allodynia, BA) in an inpatient headache population. Four types of cutaneous allodynia (heat, cold, static mechanical [pressure], and dynamic mechanical [brush] allodynia) can be studied in headache patients. In episodic migraineurs, the development of cutaneous allodynia heralds a change in treatment response. However, little is known about the functional significance of BA, and little is known about the frequency of any type of cutaneous allodynia among patients with chronic or more severe headache disorders. Methods.-The protocol was approved by the institutional review board of our university hospital. A total of 78 subjects were tested for allodynia on days 1, 3, and 5 of an inpatient hospital stay using a 4 x 4 folded gauze pad stroked 10 times at three bilateral sites (forehead, jaw, and forearm). Subjects were queried about the signs and symptoms of their headaches. Headache intensity was graded with a verbal 11-point scale and the intensity of allodynia was graded using a 10 cm visual analog scale. A total of 61 patients had transformed migraine (TM). BA was present at some point during the hospitalization in 32 subjects (41%). Neither age nor duration of daily headache correlated with headache severity. Headache intensity, a history of sensory symptoms or weakness, and subjective blurred vision accompanying the headache correlated with the presence of BA (P< or = .05). Unilateral headaches were more likely to be associated with BA (P = .01), independent of headache severity. When headache was unilateral, BA was greatest ipsilateral to the headache. BA did not influence outcome as measured by length of stay or the likelihood of being discharged headache-free. The rate of decline of headache intensity and allodynia score were similar. BA is common in hospitalized headache patients. Subjects with more severe unilateral headaches were more likely to have BA. The presence of BA did not predict treatment failure in an inpatient setting.

The Effects of Greater Occipital Nerve Block and Trigger Point Injection on Brush Allodynia and Pain in Migraine

To evaluate the effect of GONB, with or without trigger point injection (TPI), on dynamic mechanical (brush) allodynia (BA) and on head pain in migraine. Background.-Patients with migraine often have cutaneous allodynia that is related to sensitization of central pain neurons. Greater occipital nerve block (GONB) is an effective treatment for migraine headache; however, its effect on cutaneous allodynia in migraine is unknown. We studied patients with migraine and BA who were treated with GONB with or without TPI. Demographic data, migraine history, and headache features were documented. Allodynia was evaluated using a structured questionnaire and by applying a 4 x 4-inch gauze pad to skin areas in the trigeminal and cervical dermatomes. Degree of allodynia (the allodynia score) was measured on a 100-mm visual analog scale (VAS) before treatment and 10 and 20 minutes thereafter. Headache levels were assessed using an 11-point verbal scale. Allodynia scores, as well as headache levels, before and after treatment were compared. Nineteen patients were studied. Mean age was 43.6+/-11.8 years. Twenty minutes after treatment, headache was reduced in 17 patients (89.5%) and did not change in 2 (10.5%). The average headache level was 6.53 before treatment and 3.47, 20 minutes after it. The average allodynia score decreased after 20 minutes in all patients. Average allodynia score per site was reduced by 18.69 mm and 13.74 mm in the trigeminal and cervical areas, respectively. There was a positive correlation between allodynia index, obtained through the questionnaire, and allodynia score, obtained by examination. GONB, with or without TPI, reduced both head pain and brush allodynia in this migraine patient group.

Chronic Oral Gabapentin Reduces Elements of Central Sensitization in Human Experimental Hyperalgesia

In chronic pain, increased activity from intact or damaged peripheral nerve endings results in an enhanced response in central pain transmission systems, a mechanism known as central sensitization. Central sensitization can also be invoked in human experimental models. Therefore, these models may be useful to characterize novel analgesics in humans. The anticonvulsant gabapentin has demonstrated efficacy in patients with neuropathic pain, but its mode of action remains unclear. This study examined the effects of gabapentin on signs of central sensitization (brush and pinprick hyperalgesia) in a human model of capsaicin-evoked pain, using a gabapentin dosing regimen similar to that used in the clinic. The aims were to determine whether gabapentin, dosed in a manner similar to that used in the clinic, affected the various components of central sensitization and to assess the utility of this model for characterizing novel analgesics. Intradermal capsaicin (100 microg/20 microl) was administered in the volar forearm of 41 male human volunteers to induce pain and clinical signs of central sensitization. Gabapentin (titrated to 2,400 mg daily) or placebo was given orally for 15 days in a randomized, double-blind, parallel-group design. The capsaicin test was conducted at baseline and after gabapentin or placebo. Endpoints were the size of areas of brush-evoked allodynia (with cotton gauze) and pinprick hyperalgesia (with von Frey filament), and the intensity of ongoing brush- and pinprick-evoked pain. Gabapentin significantly reduced the area of brush allodynia compared with placebo (P </= 0.05) and insignificantly attenuated the area of pinprick hyperalgesia. Gabapentin had no significant effect on spontaneous and evoked pain intensity. Oral gabapentin, administered to healthy volunteers in a regimen similar to that used in treating chronic neuropathic pain, reduces measures of central sensitization evoked by intradermal capsaicin. This suggests that the pain-relieving effect in chronic neuropathic pain condition is linked to the effect of gabapentin on central sensitization. The ability of the capsaicin model to detect the efficacy of this standard treatment of neuropathic pain suggests that it may have a predictive value for detection of efficacy in human subjects.

Dynamic Mechanical (Brush) Allodynia in Cluster Headache

To examine the occurrence of dynamic mechanical (brush) allodynia (BA) in patients with cluster headache (CH). Cutaneous allodynia was described in migraine. It was related to sensitization of neurons in the trigeminal nucleus caudalis (TNC). This phenomenon has not been previously described in cluster headache. We examined adult patients with episodic or chronic CH for the presence of BA. Demographic data and the characteristics of CH were obtained through a questionnaire. Allodynia testing was performed by repetitively applying a 4x4-inch gauze pad to skin areas in the trigeminal and cervical dermatomes. Degree of allodynia was measured on a 100-mm visual analog scale (VAS). The relations between the location and severity of headache and allodynia were assessed. Ten patients (all male, mean age 39.3) were included in the study. Seven had episodic CH (ECH) and 3 had chronic CH (CCH). Two patients were in acute attack when tested for BA. In total, 4 (40%) of the 10 patients had BA (2 [28.6%] of the 7 with ECH and 2 [66.7%] of the 3 with CCH). Median disease duration was 22 years for patients with BA and 12 years for patients without BA. Of the two patients in acute attack, one had BA, ipsilateral to the headache, which was reduced 20 minutes after treatment, along with reduced headache severity. This is the first report on the occurrence of cutaneous allodynia in CH. The presence of BA in CH may be related to CH type (episodic vs. chronic) and to the duration of disease. These results support the concept that allodynia in CH may result from a time-dependent process of neuronal sensitization.

Other: Cutaneous sensory abnormalities in children with complex regional pain syndromes (CRPS)

Diagnostic criteria for CRPS types I and II, while standardized in adults, are yet to be validated in children. We prospectively evaluated characteristics of pain and cutaneous sensitivity in children who met the modified adult IASP criteria for CRPS using standardized neurologic examinations and quantitative sensory testing (QST). After IRB approval, parental consent, and patient assent, 55 children with unilateral CRPS (52 females, 3 males) ages 7-17 years underwent neurologic examination and QST by a single blinded investigator. Differences in mechanical and thermal thresholds between the affected limb and an identical area of the contralateral asymptomatic limb were measured. Variables were compared using the Mann-Whitney U-test with a Bonferroni-corrected significance level of P < 0.01. Results: All patients developed pain and altered skin sensitivity after trauma. Two distinct groups were apparent: those with brush Allodynia (WA) and those with no brush Allodynia (NA) (median thresholds 6.6 vs. 0, P < 0.01). Groups had similar demographics, duration and type of pain, skin temperature and autonomic signs. All patients had spontaneous pain, median visual analog pain scores were similar between the WA and NA groups (6.4 vs. 5.6, P = 0.21). Cold and warm temperature sensation thresholds were slightly elevated but not significantly different between WA and NA (0.7 vs. -1.5°C; 0.2 vs. 0.6 °C, P < 0.05). Median thresholds for mechanical and thermal hyperalgesia and temporal summation of pricking pain were significantly lower in WA compared to NA group: pricking pain (6.3 vs. 0), temporal summation (8.2 vs. 0), cold pain (5.6 vs. 0.2°C)) and heat pain (-2.2 vs. 1.2°C) (all P < 0.01) Altered cutaneous sensitivity occurred more commonly in the symptomatic area of children with CRPS having mechanical allodynia compared to those with no allodynia and may reflect peripheral and/or central sensitization. Additional studies are needed to elucidate the pain mechanisms of CRPS in children.

Capsaicin-evoked mechanical allodynia and hyperalgesia cross nerve territories. Evidence for a central mechanism.

The finding in some patients with neuropathic pain that mechanical allodynia (pain evoked by light touch) and hyperalgesia (supranormal pain evoked by painful stimuli) extend beyond the territory of a single nerve or spinal sensory root (extraterritorial pain) often prompts a diagnosis of psychiatric illness. The hypothesis that focal nociceptive input in a single nerve territory can result in allodynia and hyperalgesia in a nerve territory adjacent to the input was investigated in normal human subjects. On separate days, 13 healthy volunteers each received left radial and ulnar nerve blocks. After block of either nerve, sensation remaining for three classes of afferents (A beta low-threshold mechanoreceptors, A delta nociceptors, and C polymodal nociceptors) allowed inference of the nerve territory of the adjacent nerve, and the area of overlapping innervation. On a third day, 1,000 micrograms intradermal capsaicin was administered into a site such that C-nociceptor input was confined to the ulnar nerve territory. Areas of brush allodynia and pinprick hyperalgesia were determined. Spread of brush allodynia beyond all three borders of the ulnar nerve territory occurred in 9 of 13 patients (for these subjects, range 5-28 mm), whereas spread of pinprick hyperalgesia beyond all borders of the ulnar nerve territory occurred in 12 of 13 subjects (range 1-31 mm). Spread of brush allodynia beyond the A beta border of the ulnar nerve territory occurred in 10 of 13 subjects (range 4-35 mm); and spread of pinprick hyperalgesia beyond the A delta border of the ulnar nerve territory occurred in 12 of 13 subjects (range 1-31 mm). It is concluded that activation of C-nociceptors evokes a state of central sensitization that may manifest itself by the appearance of extraterritorial pain abnormalities.