Blood flow velocity changes in migraine attacks--a transcranial Doppler study

Cerebral hemodynamics in the different phases of migraine and cluster headache

Headache is one of the most common ailments; migraine is one of the most prevalent and disabling neurological disorders and cluster headache presents as one of the most excruciating pain disorders. Both are complex disorder characterized by recurrent episodes of headache. A key feature is that various triggers can set off an attack providing the opportunity to explore disease mechanisms by experimentally inducing attacks. This review summarizes neuroimaging and hemodynamic studies in human in provoked and spontaneous attacks of migraine and cluster headache. Cerebral hemodynamics during different phases of the migraine attack demonstrate alterations in cerebral blood flow and perfusion, vessel caliber, cortical and sub-cortical function, underscoring that migraine pathophysiology is highly complex. Migraine attacks might begin in diencephalic and brainstem areas, whereas migraine aura is a cortical phenomenon. In cluster headache pathophysiology, the hypothalamus might also play a pivotal role, whereas the pattern of cerebral blood flood differs from migraine. For both disorders, alterations of arterial blood vessel diameter might be more an epiphenomenon of the attack than a causative trigger. Studying cerebral hemodynamics in provocation models are important in the search for specific biomarkers in the hope to discover future targets for more specific and effective mechanism-based anti-headache treatment.

Vasomotor reactions in the face and head of patients with migraine

Objective:

To systematically review extracranial vasomotor reactions in patients with migraine, and to discuss potential overlaps with rosacea.

Background:

Autonomic manifestations are common in migraine and may reflect trigeminovascular system activation. Flushing during migraine attacks may indicate altered extracranial vasomotor reactivity which resembles that of the facial skin disorder rosacea.

Methods:

PubMed and EMBASE were searched for studies investigating extracranial vascular reactions in migraine and rosacea published until January 2018.

Results:

We uncovered 41 studies investigating extracranial circulation in migraine and 12 studies in rosacea. Skin temperature was generally lower on the forehead, nose and hands of migraine patients compared to controls. The superficial temporal artery (STA) showed greater amplitude variations in migraine patients compared to controls, and compression of either the STA or the common carotid artery during attacks led to transient pain relief in about one-third of the investigated patients. Facial skin blood flow was asymmetrical in migraine patients compared to healthy volunteers.

Conclusion:

Findings on extracranial microcirculation suggest an altered function of the autonomic nervous system in migraine patients. Similar signs of autonomic nervous system dysfunction are reported in rosacea. We suggest an overlap in autonomic and neurovascular pathophysiology in migraine and rosacea.

Cerebral blood flow velocity in migraine and chronic tension-type headache patients

Introduction

The present study seeks to use transcranial Doppler ultrasound to evaluate cerebral blood flow velocities in anterior and posterior circulation arteries, during an attack-free episode in migraine patients, with and without aura, as well as in chronic tension-type headache patients who were not receiving prophylactic medication.

Methods

A total of 50 patients (35 female, 15 male) were evaluated during a headache-free episode: 30 migraine patients without aura (mean age: 32±8 years), 10 migraine patients with aura (mean age: 34±4 years), and 10 patients with chronic tension-type headache (mean age: 34±5 years).

Results

No significant difference was present between anterior, middle, and posterior cerebral and vertebral arteries' blood flow velocities between migraine patients, with and without aura, or in patients with a tension-type headache, and normal controls (p>0.05). However, a significant increase in basilar artery cerebral blood flow velocities relative to controls was present in patients with a tension-type headache (p>0.001).

Conclusion

It is difficult to predict the main reason for the significant increase in basilar artery blood flow velocities in patients with chronic tension-type headache. It may be due to constriction of conductance or the dilatation of the resistance vessels.

Therapeutic use of botulinum toxin in migraine: mechanisms of action

Migraine pain represents sensations arising from the activation of trigeminal afferents, which innervate the meningeal vasculature and project to the trigeminal nucleus caudalis (TNC). Pain secondary to meningeal input is referred to extracranial regions innervated by somatic afferents that project to homologous regions in the TNC. Such viscerosomatic convergence accounts for referral of migraine pain arising from meningeal afferents to particular extracranial dermatomes. Botulinum toxins (BoNTs) delivered into extracranial dermatomes are effective in and approved for treating chronic migraine pain. Aside from their well-described effect upon motor endplates, BoNTs are also taken up in local afferent nerve terminals where they cleave soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins, and prevent local terminal release. However, a local extracranial effect of BoNT cannot account for allthe effects of BoNT upon migraine. We now know that peripherally delivered BoNTs are taken up in sensory afferents and transported to cleave SNARE proteins in the ganglion and TNC, prevent evoked afferent release and downstream activation. Such effects upon somatic input (as from the face) likewise would not alone account for block of input from converging meningeal afferents. This current work suggests that BoNTs may undergo transcytosis to cleave SNAREs in second-order neurons or in adjacent afferent terminals. Finally, while SNAREs mediate exocytotic release, they are also involved in transport of channels and receptors involved in facilitated pain states. The role of such post-synaptic effects of BoNT action in migraine remains to be determined.

Sensitization of the trigeminovascular pathway: perspective and implications to migraine pathophysiology

Migraine headache is commonly associated with signs of exaggerated intracranial and extracranial mechanical sensitivities. Patients exhibiting signs of intracranial hypersensitivity testify that their headache throbs and that mundane physical activities that increase intracranial pressure (such as bending over or coughing) intensify the pain. Patients exhibiting signs of extracranial hypersensitivity testify that during migraine their facial skin hurts in response to otherwise innocuous activities such as combing, shaving, letting water run over their face in the shower, or wearing glasses or earrings (termed here cephalic cutaneous allodynia). Such patients often testify that during migraine their bodily skin is hypersensitive and that wearing tight cloth, bracelets, rings, necklaces and socks or using a heavy blanket can be uncomfortable and/or painful (termed her extracephalic cutaneous allodynia). This review summarizes the evidence that support the view that activation of the trigeminovascular pathway contribute to the headache phase of a migraine attack, that the development of throbbing in the initial phase of migraine is mediated by sensitization of peripheral trigeminovascular neurons that innervate the meninges, that the development of cephalic allodynia is propelled by sensitization of second-order trigeminovascular neurons in the spinal trigeminal nucleus which receive converging sensory input from the meninges as well as from the scalp and facial skin, and that the development of extracephalic allodynia is mediated by sensitization of third-order trigeminovascular neurons in the posterior thalamic nuclei which receive converging sensory input from the meninges, facial and body skin.

Transcranial Doppler measurements in migraine and nitroglycerin headache

The objective of this study was to examine the cerebral circulation during spontaneous migraine attacks and to compare changes to an experimental headache model induced by nitroglycerin (NTG) infusion. This prospective study was carried out in a tertiary care hospital on migraineurs with or without aura. Healthy volunteers served as controls. There were no interventions. Flow velocity (FV) and pulsatility index (PI) were measured in migraineurs between and during headache attacks. In controls, FV and PI of the middle cerebral arteries were performed at baseline and after each IV infusion of 0.125, 0.25 and 0.5 microg/kg/min of NTG. In migraineurs, a significant increase in the mean flow velocity (MFV) in the left vertebral artery (VA) and the PI of the right VA during spontaneous migraine headache was found. In controls, all FV significantly decreased after infusion of NTG. The NTG model produces expected and substantially different vascular effects than those seen with spontaneous migraine headache.

Reduced impact of migraine in everyday life: an observational study in the Dutch Society of Headache Patients

OBJECTIVE

To explore the percentage of patients who report a reduced impact of migraine on their life, and to which factors this improvement can be attributed.

METHODS

Four hundred forty-eight members of the Dutch Society of Headache Patients answered a set of structured questionnaires, including the Migraine-Specific Quality of Life instrument (MSQOL).

RESULTS

Of this group, 70% reported a reduced impact of migraine. The most frequently reported reason for this reduction was a change in medication (77%); in particular, change to a triptan. Other favorable factors included a change in life-style (56%): 42% of patients reported more relaxed coping with migraine, a reduction of stress in general (28%) and of stress related to work (24%), and leading a more regular life-style (21%). In addition, social support was frequently mentioned, particularly that offered by the Dutch Society of Headache Patients (58%), family (46%), and their general practitioner (28%). The patients who reported a reduced impact of migraine had less migraine attacks and a higher quality of life than those who did not report such a reduction.

CONCLUSION

The results confirm that factors that are proven effective in clinical trials on migraine also have these effects outside a formal experimental environment.

Normalization of high interictal cerebrovascular reactivity in migraine without aura by treatment with flunarizine

BACKGROUND

Modification of migraine-associated cerebrovascular reactivity may provide insight into the mechanism of action of a given therapeutic intervention.

METHODS

With transcranial Doppler and a breath-holding index, cerebrovascular reactivity to hypercapnia was evaluated in 20 patients with migraine without aura interictally and in 11 healthy controls. Patients were started on prophylactic treatment with flunarizine 10 mg per day, and measurements were repeated at the end of every month for 3 months. Headache status was evaluated clinically via a headache index. Headache index; breath-holding index; systolic, diastolic, and mean blood flow velocities; and pulsatility index measurements were recorded at every session.

RESULTS

The baseline breath-holding index was significantly higher in the migraine group compared to the control group (P =.002). No difference in other parameters was found between the groups. The change in the headache index was significant (P<.001), indicating a beneficial effect from flunarizine. The breath-holding index improved significantly after treatment (P<.001), and the baseline difference in the breath-holding index between the pretreatment migraine group and the control group was no longer evident at 3 months. There was no significant change with treatment in the other transcranial Doppler parameters.

CONCLUSIONS

Our finding of unchanged blood flow velocities but normalized cerebrovascular reactivity after treatment suggests that the mechanism of action of flunarizine in migraine does not involve a vasodilatory effect on cerebral vessels. It may be instead that flunarizine modifies cerebrovascular reactivity through its action on centrally located structures that subserve autonomic vascular control.

Quality of life in young Italian patients with primary headache

OBJECTIVE

To compare the quality of life of young Italian patients with headache with that of the juvenile Italian population free of chronic disease.

METHODS

The Quality of Life Headache in Youth (QLH-Y) Questionnaire developed by Dutch investigators was translated into Italian and validated in a young Italian population. The forward/backward translation and, for psychometric testing, the factor analysis and Cronbach coefficient alpha were used. A new instrument (Questionnaire for Young Subjects Affected by Primary Headache) was developed to assess psychological, physical, and social functioning and functional status and was used to compare the quality of life of the patients with headache with that of headache-free controls. For psychometric testing (via the questionnaire), we selected a sample of 394 subjects (178 males and 216 females, aged 10 to 18 years): 320 subjects from three schools of North Italy and 74 patients with headache from the Paediatric Headache Center of Padua. In the latter group, 48 patients had tension-type headache and 26 had migraine without aura, according to the International Headache Society diagnostic criteria.

RESULTS

The data derived from the comparison of 84 headache-free subjects (control group) and the 74 young patients with headache confirmed that primary headache negatively influenced the latter's quality of life: patients scored significantly (P<.05) lower on psychological, physical, and social functioning than the headache-free controls.

CONCLUSIONS

Quality of life is compromised significantly in young patients with primary headache disorders. The questionnaire used in this study is a valid and reliable self-administered instrument that may facilitate clinical research in headache.

Intranasal lidocaine for the treatment of migraine headache: a randomized, controlled trial

OBJECTIVE

To evaluate the effect of intranasal lidocaine for immediate relief (5 minutes) of migraine headache pain.

METHODS

A randomized, double-blind, placebo-controlled clinical trial at two university-affiliated community teaching hospitals enrolled patients 18-50 years old with migraine headache as defined by the International Headache Society. Patients who were pregnant, lactating, known to abuse alcohol or drugs, or allergic to one of the study drugs, those who used analgesics within two hours, or those with a first headache were excluded. Statistical significance was assessed by using chi-square or Fisher's exact test for categorical variables and Student's t-test for continuous variables. Patients rated their pain on a 10-centimeter visual analog scale (VAS) prior to drug administration and at 5, 10, 15, 20, and 30 minutes after the initial dose. Medication was either 1 mL of 4% lidocaine or normal saline (placebo) intranasally in split doses 2 minutes apart and intravenous prochlorperazine. Medications were packaged so physicians and patients were unaware of the contents. Successful pain relief was achieved if there was a 50% reduction in pain score or a score below 2.5 cm on the VAS.

RESULTS

Twenty-seven patients received lidocaine and 22 placebo. No significant difference was observed between groups in initial pain scores, 8.4 (95% CI = 7.8 to 9.0) lidocaine and 8.6 (95% CI = 8.0 to 9.2) placebo (p = 0.75). Two of 27 patients (7.4%, 95% CI = 0.8, 24.3) in the lidocaine group and three of 22 patients (13.6%, 95% CI = 2.8 to 34.9) in the placebo group had immediate successful pain relief (p = 0.47), with average pain scores of 6.9 (95% CI = 5.9 to 7.8) and 7.0 (95% CI = 5.8 to 8.2), respectively. No difference in pain relief was detected at subsequent measurements.

CONCLUSION

There was no evidence that intranasal lidocaine provided rapid relief for migraine headache pain in the emergency department setting.

Lysine-acetylsalicylic acid in acute migraine attacks

Vasoconstrictive agents have been widely used in the treatment of migraine. These types of drugs have various side effects and are not suitable for many patients. Due to nausea or vomiting, nonoral treatment is often required, but only a few nonvasoconstrictive drugs exist in a parenteral form and are suitable for the treatment of acute migraine in the emergency setting. In a randomized, double-blind, crossover trial we evaluated the efficacy of 1,000 mg lysine-acetylsalicylic acid i.v. (LAS) compared to 0.5 mg ergotamine s.c. in 56 patients (112 attacks) with acute migraine. To gain further insight into the possible role of vasoconstriction, blood flow velocities (BFV) were measured in intra- and extracranial arteries using duplex sonography and transcranial Doppler sonography. Both agents were equally potent in relieving headache. Intravenous LAS resulted in a significantly faster relief and had fewer side effects. LAS had no effect on BFV. Ergotamine increased BFV in the middle cerebral artery only. No correlation was found between changes in BFV and the relief of headache. This is the first trial to compare the intravenous formulation of LAS in the treatment of migraine with another antimigraine medication and suggests that it is an effective and safe drug for the parenteral treatment of acute migraine attacks.

Further development and testing of the migraine-specific quality of life (MSQOL) measure

OBJECTIVE

To evaluate the longitudinal performance of the migraine-specific quality of life (MSQOL) instrument.

METHODS

Psychometric tests evaluated data obtained from 1383 migraineurs who completed the 20-item MSQOL questionnaire during a noncomparative, long-term, observational study of zolmitriptan (Zomig), 5 mg, for the acute treatment of migraine attacks of any intensity.

RESULTS

There was a relationship between a history of a high frequency of migraine attacks and low baseline MSQOL scores, indicating a lower quality of life. Principal components analyses confirmed three domains and an overall score. Cronbach alpha coefficients for the overall score (.93) indicated high internal consistency. Responsiveness analysis over 180 days of treatment indicated a significantly greater improvement in MSQOL scores (P <.05) in treatment responders compared with nonresponders. The average effect size (0.25) and Guyatt responsiveness statistic (0.46) for the MSQOL instrument exceeded those for the eight domains of the Medical Outcomes Study Short Form Health Survey (MOS SF-36) (-0.05 to 0.14 and 0.01 to 0.12, respectively). Change from baseline for responders in MSQOL total score was 4.7 to 5.4 compared with 1.1 to 2.7 for nonresponders.

CONCLUSIONS

Cumulative evidence for the MSQOL instrument meets established criteria for validity, consistency, and reproducibility and shows moderate responsiveness to treatment. This instrument fulfils the need for an MSQOL measure to be used as an adjuvant measure in the assessment of long-term outcomes of therapy.

Serotonin in migraine: theories, animal models and emerging therapies

A role for serotonin in migraine has been supported by changes in circulating levels of serotonin and its metabolites during the phases of a migraine attack, along with the ability of serotonin-releasing agents to induce migraine-like symptoms. The development of serotonin receptor agonists with efficacy in the clinic for the alleviation of migraine pain further implicates serotonin as a key molecule in migraine. Several theories regarding the etiology of migraine have been proposed. The vasodilatory theory of migraine suggested that extracranial arterial dilation during an attack was related to migraine pain; a theory supported when vasoconstrictors such as sumatriptan alleviated migraine pain. The neurological theory of migraine proposed that migraine resulted from abnormal firing in brain neurons. Cortical spreading depression, one facet of the neurological theory, could explain the prodrome of migraine. The neurogenic dural inflammation theory of migraine supposed that the dural membrane surrounding the brain became inflamed and hypersensitive due to release of neuropeptides from primary sensory nerve terminals. Substance P, calcitonin gene related peptide and nitric oxide are all though to play a role in the dural inflammatory cascade. Animal models of migraine have been utilized to study the physiology of migraine and develop new pharmaceutical therapies. One model measures the shunting of blood to arteriovenous anastomoses based on a proposal that migraine primarily involves cranial arteriovenous vasodilation. Another model utilizes electrical stimulation of the trigeminal ganglion to induce neurogenic dural inflammation quantified by the resulting extravasation of proteins. Pharmacological agents such as meta-chlorophenylpiperazine (mCPP) and nitroglycerin have also been used to induce dural extravasation in animals. Both compounds also induce migraine attacks in individuals with a history of migraine. In addition, Fos, a protein produced by activation of the c-fos gene, has been measured as an index of migraine-like pain transmission to the CNS following chemical or electrical stimulation of the trigeminal nerve. A role for serotonin in migraine is further supported by the efficacy of serotonin receptor ligands. Sumatriptan is an agonist at 5-HT1D and 5-HT1B receptor subtypes, and effective in treating migraine pain and associated symptoms. Recently, selective 5-HT1F agonists have been proposed for the treatment of migraine, without the side effects associated with the present 5-HT1D and 5-HT1B receptor agonists. A role for 5-HT2B receptors has also been suggested the initiation of migraine, supporting use of selective 5-HT2B receptor antagonists in migraine. Thus, agents that modulate 5-HT1B, 5-HT1D, 5-HT1F and 5-HT2B receptors either have or may have clinical utility in the therapy of migraine headache.

The pharmacodynamics of sumatriptan in nitroglycerin-induced headache

Migraine is a common disorder that causes significant morbidity in those afflicted. Many novel antimigraine compounds are in clinical development, yet full characterization of each one's pharmacodynamic behavior is a formidable task due to the difficulty in studying a migraineur during an attack. Nitroglycerin (NTG) administration commonly causes a headache with some features similar to those of a migraine. As such, NTG has been used as a model of vascular headaches, including migraine. The pharmacodynamic effects of nitroglycerin and sumatriptan on middle cerebral artery blood flow velocity (MCAv) and headache scores were studied in 10 healthy male volunteers. An intravenous infusion of NTG titrated to 0.5 mcg/kg/min over 30 minutes resulted in a median reduction from baseline in MCAv of 27% (range: 16.4%-37.3%). Nine of the subjects developed a headache with a median verbal score of 3.5 of 10 (range: 0-5). Subjects received sumatriptan either 2 mg intravenously or 6 mg subcutaneously, which abated clinical headache in 9 of the 10 subjects (p = 0.030). A median sumatriptan-induced increase in MCAv of 21% (p = 0.054) suggested a constricting effect on the NTG-induced dilated MCA. A two-compartment pharmacokinetic/indirect-effects pharmacodynamic model was fit to the sumatriptan concentration and MCAv data using iterative two-stage analysis. This model was unbiased and fit the concentration (r2 = 0.98) and the MCAv (r2 = 0.79) data well. These results suggest that NTG-induced headache and the development of pharmacokinetic/pharmacodynamic models could serve as a useful method for exploring the mechanisms of abortive migraine drugs.

Changes in cerebral blood flow velocity after treatment with sumatriptan or placebo and implications for the pathophysiology of migraine

Whether the primary mechanisms of migraine are vascular or neurogenic is, as yet, unresolved. In humans it is still unclear whether sumatriptan acts via constriction of dilated arteries or through other mechanisms. Doppler sonography is a non-invasive method for measuring blood flow velocities (BFV), an indirect marker of vessel diameter. This double-blind crossover placebo-controlled trial investigated changes in BFV in extra- and intracranial arteries in 132 migraine attacks (66 patients) before and after treatment with either 6 mg sumatriptan s.c. or placebo. Significant increases in BFV were observed only in the middle cerebral artery (MCA) and the basilar artery (BA) after administration of sumatriptan. However, the majority of the patients showed no change in BFV following sumatriptan. No difference in BFV could be detected between headache and non-headache side or between migraine and headache free periods. Despite a slight increase in BFV in intracerebral arteries, this study does not support the concept that vasoconstriction is sumatriptan's principal mechanism in pain relief.

Cerebral blood flow velocities are reduced during attacks of unilateral migraine without aura

It has been disputed whether or not large intracranial arteries are dilated during migraine attacks. In order to answer this question the present transcranial Doppler study focused on side-to-side differences of middle cerebral artery blood velocity during unilateral attacks of migraine without aura in 25 patients. Blood velocity in the middle cerebral artery was lower on the headache side (59 cm/s) than on the non-headache side (65 cm/s) during the migraine attack. No such difference was found outside of attack (65 cm/s both sides). The difference (headache side minus non-headache side) was on average -6.1 cm/s during attack compared to -0.4 cm/s outside of attack (p = 0.01). Assuming that rCBF is unchanged during attacks of migraine without aura, our results suggest a 9% increase in middle cerebral artery lumen (cross-sectional area) on the affected side during unilateral attacks of migraine without aura. The findings, however, do not necessarily mean that arterial dilatation is the only or even the most significant cause of pain.

CO2 measurements during transcranial Doppler examinations in headache patients: methodological considerations

Transcranial Doppler (TCD) examinations are increasingly being used in studies of headache pathophysiology. Because blood velocity is highly dependent on PCO2, these parameters should be measured simultaneously. The most common way of performing measurements during TCD examinations is as end-tidal pCO2 with a capnograph. When patients are nauseated and vomit, as in migraine, the mask or mouthpiece connected to the capnograph represents a problem. We therefore evaluated whether a transcutaneous pCO2 electrode was as useful as the capnograph for pCO2 measurements in TCD examinations. We conclude that this is not the case, and recommend capnographic end-tidal pCO2 measurements during TCD examinations. However, transcutaneous pCO2 measurements may represent a supplement to spot measurements of end-tidal pCO2 in stable conditions when long-term monitoring is needed, and the mask or mouthpiece of the capnograph has to be taken on and off between recordings.

Endothelin 1 in migraine and tension-type headache

We determined the plasma levels of ET1, both interictally and ictally, in 50 migraine patients, 20 with aura (MPA) and 30 without aura (MPWA), comparing them with the levels of 40 age-matched tension-type headache patients (20 episodic and 20 chronic) (ETTHP and CTTHP) and the levels of a group of 20 healthy control subjects (CS). No statistically significant difference was evident between the mean ET1 plasma levels of MPA and those of MPWA, assessed in headache-free periods. The mean ET1 plasma levels of MPA and MPWA, assessed interictally, were significantly higher than those of CS. However, the values of plasma ET1 in ETTP and in CTTHP did not differ statistically from those of CS. MPA and MPWA ET1 plasma levels increased significantly within 2 h from the onset of attacks (p < 0.0001) and remained significantly higher between 4 and 6 h from the onset. The ET1 plasma levels of ETTHP and CTTHP assessed during attacks did not differ statistically from those of the same patients assessed in the headache-free periods. The increase in ET1 levels in MPA and MPWA patients when assessed ictally, suggests that this peptide is involved in the haemodynamic changes and vascular tone modifications observed during migraine attacks, particularly in the first phase of the ictal period.

Lack of asymmetry of middle cerebral artery blood velocity in unilateral migraine

BACKGROUND AND PURPOSE

A recent transcranial Doppler study found reduced blood velocity in seven patients during migraine attacks in the middle cerebral artery at the headache side. This would implicate vasodilation of the middle cerebral artery in the pathogenesis of headache in migraine. We attempted to confirm this finding.

METHODS

We determined blood velocity with transcranial Doppler ultrasonography in the middle cerebral arteries of 51 migraine patients with unilateral headache (5 with aura, 46 without aura) and of 14 patients with bilateral headache, during and outside attacks. During attacks, median time from onset of attack to transcranial Doppler examination was 6 hours (range, 1 to 35 hours).

RESULTS

We found no difference between blood velocity at the headache and nonheadache sides nor between blood velocity during and outside attacks. Similar results were obtained in a subgroup of 11 patients who were investigated in the first 4 hours of an attack. There were also no differences between attacks with unilateral or bilateral headache.

CONCLUSIONS

We cannot support the hypothesis that migraine is associated with vasodilation of the middle cerebral artery ipsilateral to the headache.

Human brain measures of clinical pain: a review. II. Tomographic imagings

This paper (Parts I and II) reviews the measures employed in studying the brain neurophysiological activities of clinical pain. In Part II, these measures include the imaging and measurement of brain blood flow and hemodynamics in various regions of the brain, the scanning of gross and fine brain structures by computerized axial tomography or magnetic resonance imaging, and the imaging and measurement of brain metabolic changes, energy uptake, and receptors bindings through positron emission tomography or single-photon emission computerized tomography. Molecular chemical transformation by the nuclear magnetic resonance analysis of tissue changes and analgesic-receptor interactions is also noted. Most studies of the cerebral measures of traumatic and pathophysiological pain reported in the literature are concerned with headache. The relationships of brain activities among sensory processes of nociception, subjective experience of pain intensity and quality, emotional reaction, and cognitive coping often are complex and not well elucidated in man. Although significant changes in the cerebral physiological parameters are frequently reported in pain patients, the specificity and sensitivity of these measures as objective markers for human pain, reviewed from Part I and Part II together, has not yet been conclusively defined. Also, normative data basis and criteria for classifying abnormality of these brain measures must be established and their validity and reliability be carefully examined so that they can be confidently applied in diagnosis and management of clinical pain. Nevertheless, advancement on measurement of temporal dynamics in 3-D topographic mapping of cortical activities and source localization modeling, together with tomographic imaging of neurochemical metabolisms in the brain will further our scientific understanding of cerebral pain mechanisms. A window on the brain of human pain is being opened.

Clinical and experimental effects of sumatriptan in humans

Recent reviews on the mode of action of the anti-migraine drug sumatriptan arrived at contrasting conclusions. Whereas some reviewers concluded that vasoconstriction is the most important action, others suggest that neuronal inhibition is essential. Both views were based predominantly on animal or in vitro experiments. In this comment, Michel Ferrari and Pramod Saxena review the experimental effects of sumatriptan in humans and discuss the clinical validity of both theories. In addition, they examine the initial efficacy of treatment and the mechanism of recurrence of headache within 24 hours, which is the most important drawback of sumatriptan in clinical practice, next to its possible cardiac side effects.

Neurogenic versus vascular mechanisms of sumatriptan and ergot alkaloids in migraine

Sumatriptan and the ergot alkaloids are useful tools for deciphering drug mechanisms in migraine and related headaches. Both neuronal and vascular mechanisms have been proposed on the basis of actions of 5-HT at receptors resembling the 5-HT1D subtype. In this Viewpoint article, Michael A. Moskowitz argues that blockade of neural transmission and the neurogenic inflammatory response provides a mechanism by which sumatriptan and ergot alkaloids alleviate vascular headaches. He postulates, with similar arguments, that sumatriptan and ergot alkaloids may block headaches that develop from meningovascular inflammatory disorders such as from viral and bacterial meningitis and from the sequelae of head injury.

Migraine with aura-like syndrome due to arteriovenous malformation. The clinical value of transcranial Doppler in early diagnosis

Arteriovenous malformations are an acknowledged cause of migraine that can long constitute the only clinical manifestation before bleeding. We describe two cases of patients suffering from symptoms like migraine with aura in whom arteriovenous malformations were detected by transcranial Doppler examination. We suggest that a screening of migraine patients to prevent bleeding from a possible underlying unruptured arteriovenous malformation could be performed by using transcranial Doppler, a non-invasive and low cost examination.

Blood flow velocities in the vertebrobasilar system during migraine attacks--a transcranial Doppler study

In this study, blood flow velocity in the basilar artery and both vertebral and middle cerebral arteries was measured with a transcranial Doppler device in 23 migraineurs during and outside a migraine attack. The aim of the study was to compare blood flow velocities during and outside an attack and to examine vascular reactivity to voluntary hyperventilation during both conditions. No differences in blood flow velocity were found. Although blood pressure was increased and end-expiratory CO2 decreased during the attack, this exerted no influence on blood flow velocity. Neither was a difference in vascular reactivity to voluntary hyperventilation detected between the two conditions. These findings support the notion of functional integrity of the examined large arteries during migraine attacks without aura.