Pain, 47 (1991) 145-149 © 1991 Elsevier Science Publishers B.V. All rights reserved 0304-3959/91/$03.50

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PAIN 01882

Cephalic and extracephalic pressure pain thresholds in chronic tension-type headache J. Schoenen ~, D. Bottin b, F. Hardy ~ and P. Gerard ~ Departments of " Neurology, Headache Clinic, and b Gynaecology and Obstetrics, CHR Citadelle, UniL,ersity of Libge, Liege (Belgium) (Received 23 November 1990, revision received 25 February 1991, accepted 20 March 1991)

Summary Pressure pain thresholds were assessed with an algometer (Somedic Inc.), over the forehead, temple and suboccipital region as well as over the Achilles tendon. A group of 32 patients suffering from chronic tension-type headache was compared to 20 healthy controls and to 10 migraineurs without aura. Although individual values were widely scattered, pressure pain thresholds were on average significantly lower in chronic tension-type headache, not only at pericranial sites but also over the Achilles tendon. Only 50% of these patients had one or more pericranial thresholds 1.5 S.D. below the mean of controls. After muscular biofeedback therapy, all pain thresholds were on average increased. Along with results obtained previously, the present data support the hypothesis that diffuse disruption of central pain-modulating systems, possibly due to a modified limbic input to the brain-stem, is pivotal in the pathophysiology of chronic tension-type headache. Key words: Chronic tension-type headache; Migraine without aura; Pain thresholds; Pressure algometer

Introduction

The pathogenetic mechanisms underlying tensiontype headache are still unclear. Abnormal contraction of pericranial and neck muscles has been considered a possible cause of pain, but electromyographic activity in these muscles is increased only in a proportion of patients and under certain recording conditions [1,8,10,20,22]. Tenderness of pericranial muscles is a common finding in tension-type headache sufferers [3,6,15] but also in patients presenting other types of headache [18] or in so-called primary fibromyalgia [29]. It has been suggested that disregulation of endogenous pain control systems, so-called "central dysnociception," may play a pivotal pathophysiologic role in idiopathic headaches [25]. Abnormal pain sensitivity was found in paravertebral muscles [16] but not in fingers [6] of patients with severe tension headache. The purpose of the present study was to determine pressure pain thresholds in pericranial muscles as well as at an extracephalic site, the Achilles tendon, in Correspondence to. Jean Schoenen, M.D., Ph.D., University Department of Neurology, Headache Unit, CHR Citadelle, Bd. du 12° de Ligne, B-4000 Liege, Belgium.

patients suffering from chronic tension-type headache and to compare them with those measured in migraineurs or healthy controls. Patients and methods

Only females were included in this study. Thirty-two patients presenting with the chronic form of tensiontype headache (mean age: 41 + 8 years) were compared with ten patients suffering from mirgraine without aura (mean age: 39 + 10 years) and with a group of twenty female healthy volunteers of comparable ages (mean age: 40 + 9 years). Clinical diagnoses were made by one of us (J.S.) according to the operational criteria of the new Headache Classification of the International Headache Society (code 2.2) [4]. Patients taking more than 3 analgesic tablets/week or treated with psychotropic drugs were excluded, as were patients who had taken such drugs less than 24 h before investigation. Migraineurs did not receive prophylactic therapy and were recorded in headache-free intervals. In patients and controls, degree of tenderness to manual palpation and pain thresholds using a pressure algometer were evaluated at three pericranial spots and at the Achilles tendon 1 cm above the calcaneum.

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The per•cranial sites chosen were the temple ( u p p e r a n t e r i o r part of the temporalis muscle), the forehead Oust above the superciliary notch) and the suboccipital region (at the suboccipital fossa). Since a previous pilot study had shown no significant side to side differences, only m e a s u r e m e n t s m a d e on the left side of the body were taken into account. M a n u a l p a l p a t i o n was p e r f o r m e d with the 3rd finger of the right h a n d while the subject's head was supported with the left hand placed on the opposite side. T e n d e r n e s s was assessed according to a 4-point scale: 11 = no pain; 1 = report of t e n d e r n e s s without visible reaction; 2 = report of painful t e n d e r n e s s and visible reaction; 3 = report of severe pain and m a r k e d reaction [1528]. A pressure algometer (Somedic Inc.) with a tip of 0.5 cm= was used to evaluate pain thresholds [11]. It consists of a g u n - s h a p e d stinmlator, with the tip situated at the e n d of the barrel, c o n n e c t e d to a pressure t r a n s d u c e r built into the h a n d l e of the gun. Five meas u r e m e n t s with an approximate pressure loading rate of 20 k P a / s e c were p e r f o r m e d in each subject and at each spot of interest at 30 sec intervals. In our hands pain thresholds after an initial decrease r e m a i n stable from the 4th m e a s u r e m e n t onward (Fig. 1). Hence,

only values o b t a i n e d during the 4th trial were hlkcn into consideration. The subjects were asked to push the b u t t o n that i n t e r r u p t e d the digital scale of the device as soon as the pressure exerted was fell as painful. All subjects were placed in a reclining position and were evaluated m a n u a l l y as well as with the pressure algometer by two of us (D.B., F.H.) who were not aware of the clinical diagnoses. D u r i n g 5 weeks, some patients in the chronic tension-type h e a d a c h e group received 2 weekly sessions of E M G biofeedback coupled to sophrological relaxation before u n d e r g o i n g a second evaluation. For comparison b e t w e e n groups, S t u d e n t ' s t test was used. The same test for paired variables was used to assess the effect of t r e a t m e n t in the same group and S p e a r m a n ' s rank test to describe the level of correlation b e t w e e n two variables.

Results C o r r e l a t i o n b e t w e e n evaluation of t e n d e r n e s s by m a n u a l p a l p a t a t i o n a n d pain threshold m e a s u r e m e n t s m a d e with the pressure algometer (Fig. 2) was good (r = 0.65) and statistically significant ( P < 0.001). We

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Cephalic and extracephalic pressure pain thresholds in chronic tension-type headache.

Pressure pain thresholds were assessed with an algometer (Somedic Inc.), over the forehead, temple and suboccipital region as well as over the Achille...
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