Is stress a trigger factor for migraine?

BACKGROUND

Although mental stress is commonly considered to be an important trigger factor for migraine, experimental evidence for this belief is yet lacking.

OBJECTIVE

To study the temporal relationship between changes in stress-related parameters (both subjective and objective) and the onset of a migraine attack.

METHODS

This was a prospective, ambulatory study in 17 migraine patients. We assessed changes in perceived stress and objective biological measures for stress (saliva cortisol, heart rate average [HRA], and heart rate variability [low-frequency power and high-frequency power]) over 4 days prior to the onset of spontaneous migraine attacks. Analyses were repeated for subgroups of patients according to whether or not they felt their migraine to be triggered by stress.

RESULTS

There were no significant temporal changes over time for the whole group in perceived stress (p=0.50), morning cortisol (p=0.73), evening cortisol (p=0.55), HRA (p=0.83), low-frequency power (p=0.99) and high-frequency power (p=0.97) prior to or during an attack. Post hoc analysis of the subgroup of nine stress-sensitive patients who felt that >2/3 of their migraine attacks were triggered by psychosocial stress, revealed an increase for perceived stress (p=0.04) but no changes in objective stress response measures. At baseline, this group also showed higher scores on the Penn State Worry Questionnaire (p=0.003) and the Cohen Perceived Stress Scale (p=0.001) compared to non-stress-sensitive patients.

CONCLUSIONS

Although stress-sensitive patients, in contrast to non-stress-sensitive patients, may perceive more stress in the days before an impending migraine attack, we failed to detect any objective evidence for a biological stress response before or during migraine attacks.

[Narcolepsy: a new perspective on diagnosis and treatment]

The 5 classic symptoms of narcolepsy are excessive daytime sleepiness, cataplexy, sleep paralysis, hypnagogic hallucinations and disturbed nocturnal sleep. The presence of cataplexy is strongly associated with a deficiency of the neuropeptide hypocretin. This discovery has led to new diagnostic subclassifications: narcolepsy without cataplexy, which can be demonstrated by a multiple sleep latency test, and narcolepsy with cataplexy, which can be confirmed with a multiple sleep latency test or a cerebrospinal fluid deficiency of hypocretin I. Various treatment options are available, including psychostimulants and gamma hydroxybuterate.

Does modafinil enhance activity of patients with myotonic dystrophy?: a double-blind placebo-controlled crossover study

We performed a double-blind placebo-controlled crossover study in 13 patients with myotonic dystrophy to address the question whether modafinil, known to improve hypersomnolence in myotonic dystrophy, may improve levels of activity as well. We used the Epworth Sleepiness Scale as a measure of hypersomnolence and a structured interview of the patient and the partner or housemate as a measure of activity. We additionally used a restricted form of the RAND-36 to relate a possible improvement of activity to perceived general health. We confirmed earlier positive findings of modafinil regarding reduced somnolence (p = 0.015), but no significant effects were seen regarding activity levels (p = 0.2 for patients’ self-reports and 0.5 for partners’ reports).

Memory activation enhances EEG abnormality in mild cognitive impairment

This exploratory study investigated EEG power changes during memory activation in patients with amnestic mild cognitive impairment (MCI). Twelve MCI patients and 16 age-matched controls underwent EEG registration during two conventional EEG conditions ('eyes closed' and 'eyes open') and three memory conditions ('word memory', 'picture memory' and 'animal fluency'). For all conditions, EEG power in the theta (4-8 Hz), lower alpha (8-10.5 Hz) and upper alpha (10.5-13 Hz) bands were expressed as percentile changes compared to 'eyes closed'. MCI patients showed significantly less decrease in the lower alpha band than controls (p=0.04) during picture memory activation. The word memory task showed a trend towards a similar effect (p=0.09). This study suggests that memory activation reveals EEG differences between MCI patients and controls while conventional EEG conditions do not.

Interobserver variation in the interpretation of SSEPs in anoxic–ischaemic coma

OBJECTIVE

To study interobserver variation in the interpretation of median nerve SSEPs in patients with anoxic-ischaemic coma.

METHODS

SSEPs of 56 consecutive patients with anoxic-ischaemic coma were interpreted independently by 5 experienced clinical neurophysiologists using guidelines derived from a pilot study. Interobserver agreement was expressed as kappa coefficients.

RESULTS

Kappa ranged from 0.20 to 0.65 (mean 0.52, SD 0.14). Disagreement was related with noise level and failure to adhere strictly to the guidelines in 15 cases. The presence or absence of N13 and cortical peaks caused disagreement in 5 cases each. For recordings with a noise level of 0.25 microV or more, mean kappa was 0.34; for recordings with a noise level below 0.25 microV mean kappa was 0.74.

CONCLUSIONS

Interobserver agreement for SSEPs in anoxic-ischaemic coma was only moderate. Since the noise level strongly influenced interobserver variation, utmost attention should be given to its reduction. If an artefact level over 0.25 microV remains, absence of N20 cannot be judged with sufficient certainty and the SSEP should be repeated at a later stage.

SIGNIFICANCE

Because of its moderate interobserver agreement, great care has to be given to accurate recording and interpretation of SSEPs before using the recordings for non-treatment decisions.

Syncope in migraine: the population-based CAMERA study

OBJECTIVE

To examine the association between migraine and syncope-related autonomic nervous system (ANS) symptoms.

METHODS

A population-based study among migraineurs with and without aura (n = 323) and control subjects (n = 153) was conducted. A systematic questionnaire and cardiovascular measurements during rest, while standing, and after venipuncture addressed the prevalence of syncope, orthostatic intolerance, orthostatic hypotension (OH), and the postural tachycardia syndrome (POTS) in migraineurs and control subjects.

RESULTS

The lifetime prevalence of syncope in all participants was 41%, more often in women (45 vs 32%; p = 0.02). Compared with control subjects, migraineurs had a higher lifetime prevalence of syncope (46 vs 31%; p = 0.001), frequent syncope (five or more attacks) (13 vs 5%; p = 0.02), and orthostatic intolerance (32 vs 12%; p < 0.001). There was no association between ANS symptoms and the severity of migraine or migraine subtype. Cardiovascular measurements and the prevalence of POTS and OH did not differ significantly between migraineurs and control subjects.

CONCLUSION

This population-based study demonstrated an elevated prevalence of syncope and orthostatic intolerance in migraineurs without clear interictal signs of autonomic nervous system dysfunction.

Stress induced hypotension in pure autonomic failure

A 47 year old woman with pure autonomic failure complained of dizziness during emotional stress. Emotional stimuli have not previously been reported to cause hypotension in patients with autonomic failure. In the patient, ambulatory blood pressure recording revealed severe hypotension (50/30 mm Hg) after a stressful event. During a tilt table test, hyperventilation was shown to cause a significant fall of blood pressure. This suggests that emotional stress can induce hypotension, probably through hyperventilation, in subjects with autonomic failure.

Recognising F-response interference as a source of increased jitter in stimulated single fibre EMG

OBJECTIVE

To determine the source of an abnormal pattern of latency shifts leading to falsely high jitters in single fibre electromyography (SFEMG).

METHODS

We observed a sudden shortening of the latency to an individual single fibre spike component followed by a gradual return to baseline values during stimulation single fibre electromyography (SFEMG) of the facial muscle. The pattern could be reproduced in healthy controls.

RESULTS

The sudden decrease in latency proved to follow an additional discharge of the muscle fibre, not due to the external stimulus. This additional discharge was identified as an F-response.

CONCLUSIONS

The mechanism is thought to be a higher muscle fibre conduction velocity resulting from a temporary increase in stimulus frequency, in the form of an extra impulse along the muscle fibre represented by the F-response.

SIGNIFICANCE

The typical abnormal pattern should be recognised because it can falsely increase the mean jitter. We advice to increase the time base to 50 ms if this pattern is observed and to exclude the affected potentials from jitter measurements.

[Terms in use for transient loss of consciousness in the emergency ward; an inventory]

OBJECTIVE

To investigate the terminology for transient loss of consciousness in use in a Dutch emergency ward and to compare it with European definitions.

DESIGN

Descriptive.

METHOD

The records of all consecutive patients seen during an eight-week period in the Emergency Clinic of Leiden University Medical Centre, the Netherlands, were reviewed. Patients were enrolled in one of the following Dutch terms was encountered, expressing either a specific form or a general description of non-traumatic transient loss of consciousness (TLOC): 'collaps' (collapse), 'syncope' (syncope), 'flauwvallen' (fainting), 'wegraking' (TLOC) and 'insult' (seizure). The use of these terms was compared with the definitions of the European Society of Cardiology (ESC).

RESULTS

The prevalence of a non-traumatic TLOC diagnosis in the Emergency Clinic was 2.9% (123/4300). 'Collaps' was the most frequently used term (53%), followed by 'insult' (31%), 'wegraking' (11%), 'flauwvallen' (3%) and 'syncope' (2%). The term 'collaps' was found to have been used in the context of the ESC category 'syncope' (n=47), TLOC (n=5), 'no TLOC' (n=9) or for situations that could not be classified (n=4). The term 'insult' was used exclusively in the context of epilepsy and the term 'syncope' exclusively in the context of the ESC category 'syncope'. The term 'wegraking' proved to have been used in the context of the ESC category 'TLOC' (n=11), 'epilepsy' (n=1) or for situations that could not be classified (n=1). 'Flauwvallen' was used in the context of the ESC category 'syncope' (n=3) or the category 'no TLOC' (n=1).

CONCLUSION

It would be advisable to give the terms mentioned above a specific meaning: reserve 'collaps' for a fall without an obvious external cause, 'wegraking' for transient loss of consciousness without a clear cause, and 'syncope' for loss of consciousness due to temporary low cerebral blood flow.

Diagnostic value of history taking in reflex syncope

The medical history, in combination with the physical examination and a 12-lead electrocardiogram, plays a key role in the diagnosis and risk stratification of patients with syncope. However, diagnostic clinical criteria are not uniformly applied. In older studies, the diagnostic criteria for vasovagal or reflex syncope often included typical precipitating events and warning symptoms. More recent studies have documented that a variety of unrecognized stressors can trigger reflex syncope and that warning signs and symptoms may be minimal. A characteristic medical history (a trigger and/or prodromi) is enough to diagnose reflex syncope if the risk for a cardiac cause of syncope is low (e. g. patients < 65 yrs, without a history of heart disease and no ECG abnormalities). In elderly subjects with a higher risk of cardiac syncope, the yield of the medical history is lower. However, a prospective study of the value of the medical history for the diagnosis of syncope with long-term follow-up has not been performed.

Gene dosage-dependent transmitter release changes at neuromuscular synapses of Cacna1a R192Q knockin mice are non-progressive and do not lead to morphological changes or muscle weakness

Ca(v)2.1 channels mediate neurotransmitter release at the neuromuscular junction (NMJ) and at many central synapses. Mutations in the encoding gene, CACNA1A, are thus likely to affect neurotransmitter release. Previously, we generated mice carrying the R192Q mutation, associated with human familial hemiplegic migraine type-1, and showed first evidence of enhanced presynaptic Ca(2+) influx [Neuron 41 (2004) 701]. Here, we characterize transmitter release in detail at mouse R192Q NMJs, including possible gene-dosage dependency, progression of changes with age, and associated morphological damage and muscle weakness. We found, at low Ca(2+), decreased paired-pulse facilitation of evoked acetylcholine release, elevated release probability, and increased size of the readily releasable transmitter vesicle pool. Spontaneous release was increased over a broad range of Ca(2+) concentrations (0.2-5mM). Upon high-rate nerve stimulation we observed some extra rundown of transmitter release. However, no clinical evidence of transmission block or muscle weakness was found, assessed with electromyography, grip-strength testing and muscle contraction experiments. We studied both adult ( approximately 3-6 months-old) and aged ( approximately 21-26 months-old) R192Q knockin mice to assess effects of chronic elevation of presynaptic Ca(2+) influx, but found no additional or progressive alterations. No changes in NMJ size or relevant ultrastructural parameters were found, at either age. Our characterizations strengthen the hypothesis of increased Ca(2+) flux through R192Q-mutated presynaptic Ca(v)2.1 channels and show that the resulting altered neurotransmitter release is not associated with morphological changes at the NMJ or muscle weakness, not even in the longer term.

Single-fiber EMG in familial hemiplegic migraine

Twelve familial hemiplegic migraine (FHM) patients (6 with the I1811L mutation in CACNA1A, 3 with M731T mutation in ATP1A2, and 3 without known mutations) and 10 control subjects underwent single-fiber EMG. Mean jitter did not differ significantly between patients and control subjects or among patients. No blocking was found. The results suggest that neuromuscular function is normal in FHM.

Neurophysiological tests and neuroimaging procedures in non-acute headache: guidelines and recommendations

The use of instrumental examinations in headache patients varies widely. In order to evaluate their usefulness, the most common instrumental procedures were evaluated, on the basis of evidence from the literature, by an EFNS Task Force (TF) on neurophysiological tests and imaging procedures in non-acute headache patients. The conclusions of the TF regarding each technique are expressed in the following guidelines for clinical use. 1 Interictal electroencephalography (EEG) is not routinely indicated in the diagnostic evaluation of headache patients. Interictal EEG is, however, indicated if the clinical history suggests a possible diagnosis of epilepsy (differential diagnosis). Ictal EEG could be useful in certain patients suffering from hemiplegic and basilar migraine. 2 Recording of evoked potentials is not recommended for the diagnosis of headache disorders. 3 There is no evidence to justify the recommendation of autonomic tests for the routine clinical examination of headache patients. 4 Manual palpation of pericranial muscles, with standardized palpation pressure, can be recommended for subdividing patient groups but not for diagnosis. Pressure algometry and electromyography (EMG) cannot be recommended as clinical diagnostic tests. 5 In adult and paediatric patients with migraine, with no recent change in attack pattern, no history of seizures, and no other focal neurological signs or symptoms, the routine use of neuroimaging is not warranted. In patients with atypical headache patterns, a history of seizures and/or focal neurological signs or symptoms, magnetic resonance imaging (MRI) may be indicated. 6 If attacks can be fully accounted for by the standard headache classification [International Headache Society (IHS)], a positron emission tomography (PET) or single-photon emission computerized tomography (SPECT) and scan will generally be of no further diagnostic value. 7 Nuclear medicine examinations of the cerebral circulation and metabolism can be carried out in subgroups of headache patients for diagnosis and evaluation of complications, when patients experience unusually severe attacks, or when the quality or severity of attacks has changed. 8 Transcranial Doppler examination is not helpful in headache diagnosis. Although many of the examinations described are of little or no value in the clinical setting, most of the tools have a vast potential for further exploring the pathophysiology of headaches and the effects of pharmacological treatment.

Impairment of trigeminal sensory pathways in cluster headache

Cluster headache (CH) typically presents in clusters of attacks of intense (peri)orbital, unilateral pain. The distribution of the pain implies involvement of central and/or peripheral trigeminal pathways. These can be investigated by means of trigeminal somatosensory evoked potentials (TSEP) and blink reflexes (BR). We aimed to relate functional changes in trigeminal sensory pathways to the presence of cluster periods. TSEP and BR were performed in 28 episodic CH patients during a cluster period and repeated in 22 outside a cluster period. TSEP latencies (N1, P1 and N2) and amplitude (N1-P1 and P1-N2) and BR latencies (R1, R2 ipsilateral and R2 contralateral) were compared between sides, during and outside a cluster period and with healthy control data (n = 22). During a cluster period, N2 TSEP latencies were longer on the symptomatic side compared with the non-symptomatic side (27.2 +/- 3.0 ms vs. 26.3 +/- 3.4 ms, P = 0.02), and compared with the same side outside the cluster period (26.7 +/- 3.1 ms vs. 25.1 +/- 3.0 ms, P = 0.01). N1, P1 and N2 latencies on the symptomatic side in patients during the cluster period (14.8 +/- 2.3 ms, 20.4 +/- 2.5 ms and 27.2 +/- 3.0 ms, respectively) were significantly longer than those of healthy controls (13.4 +/- 1.9 ms, 18.8 +/- 2.4 ms and 25.0 +/- 2.6 ms, respectively, P < 0.03). Outside the cluster period, N1 latencies of both sides (15.3 +/- 2.8 ms symptomatic side and 15.4 +/- 2.6 ms asymptomatic side) were longer compared with controls (13.4 +/- 1.9 ms, P < 0.04). TSEP amplitudes and BR latencies revealed no significant differences. We conclude that abnormalities of the afferent trigeminal pathway are present in patients with cluster headache, most prominent during the cluster period, and on the symptomatic side. This seems primarily due of changes within the higher cerebral regions of the system.

[Initial diagnostic strategy in the case of transient losses of consciousness: the importance of the medical history]

It is estimated that almost half of the people experience a transient loss of consciousness at some time during their life. In young patients (< 35 years) the cause is mostly a reflex syncope. In older patients the common causes are orthostatic and postprandial hypotension, sinus caroticus syndrome, cardiac arrhythmias and valvular disorders. The medical history can identify a probable cause of the transient loss of consciousness in almost all young patients (< 35 years) and in the majority of older patients. A physical examination and an ECG should be performed in all patients who have experienced a transient loss of consciousness, other than those with classical vasovagal syncope, in order to exclude orthostatic hypotension and dangerous cardiac causes.

Impaired antagonist inhibition may contribute to akinesia and bradykinesia in Huntington's disease

OBJECTIVE

To test the hypothesis that besides impaired agonist facilitation, impaired antagonist inhibition also contributes to delayed initiation (akinesia) and slow execution (bradykinesia) of voluntary movements in Huntington's disease.

METHODS

Fifteen patients with Huntington's disease and 11 age-matched controls participated in the study. The amount of agonist facilitation was measured as the increase in soleus H-reflex amplitude prior to ballistic voluntary plantar flexion (soleus contraction). Antagonist inhibition was measured as the decrease in soleus H-reflex prior to ballistic dorsiflexion (tibialis anterior (TA) contraction). The amount of agonist facilitation and antagonist inhibition was correlated with the time needed for motor initiation (reaction time) and movement execution (movement time).

RESULTS

Starting 50ms prior to soleus contraction, soleus H-reflex increased in control subjects but less so in patients. Soleus H-reflexes decreased in controls 25ms prior to TA contraction, while this antagonist inhibition was completely lacking in patients. Thus, patients with Huntington's disease not only displayed reduced agonist facilitation, but impaired antagonist inhibition as well. Moreover, more impairment of antagonist inhibition correlated significantly with more severe akinesia and bradykinesia.

CONCLUSIONS

Antagonist inhibition prior to and during agonist contractions is markedly impaired in Huntington's disease. This impairment might contribute to motor slowness in these patients.

Reproducibility and feasibility of neurophysiological assessment of the sensory trigeminal system for future application to paroxysmal headaches

As the distribution of pain in primary headaches suggests involvement of the trigeminal sensory pathways, trigeminal somatosensory evoked potentials (TSEP) and blink reflexes (BR) may provide important information about their functional integrity. Functional differences between symptomatic and non-symptomatic sides and between measurements during and outside attacks may be particularly informative. These tests should therefore be reproducible and should require a suitable number of patients for future studies in patients with primary, paroxysmal headaches. We performed TSEP and BR twice in 22 healthy volunteers, in order to calculate sample sizes based on reproducibility data. This is, to our knowledge, the first study investigating the reproducibility of TSEP and BR measurements. Latencies of TSEP and BR are appropriate for future studies, as their reproducibility allows practical sample sizes (less than 25 subjects). Duration, amplitude and area parameters of the BR responses were less appropriate for longitudinal studies.

Obstetric lesions of the brachial plexus

The few studies on prognosis of obstetric lesions of the brachial plexus that are not hampered by selection bias or a short follow-up suggest that functional impairment persists in 20-25% of cases, more than commonly thought. Electromyography (EMG), potentially useful for prognosis, is often considered of little value. Denervation in the first week of life has been interpreted as evidence of an antenatal lesion, but is the logical result of the short axonal length affected. EMG performed at close to the time of possible intervention (3 months) usually shows a discrepancy: motor unit potentials are seen in clinically paralyzed muscles. This can be explained in five ways: an overly pessimistic clinical examination; overestimation of EMG recruitment due to small muscle fibers; persistent fetal innervation; developmental apraxia; or misdirection, in which axons reach inappropriate muscles. Further research into the pathophysiology of obstetric lesions of the brachial plexus is needed to improve prognostication.

Patients with the major and minor form of hyperekplexia differ with regards to disynaptic reciprocal inhibition between ankle flexor and extensor muscles

The aim of the present study was to investigate the contribution of reciprocal inhibition to muscle tone by examining the transmission in the reciprocal inhibitory pathway in patients with a known defect in the glycine receptor. The study was performed in eight patients with hereditary hyperekplexia, six with the major form and two with the minor form of the disease. A mutation in the alpha1-subunit of the glycine receptor had been demonstrated in the patients with the major form, whereas no mutation was seen in the patients with the minor form. Disynaptic reciprocal inhibition, which is presumed to be mediated by glycine, was not seen in the patients with the major form of the disease, while it could be evoked in the patients with the minor form of the disease. Presynaptic inhibition, which is presumed to be mediated by GABA, was seen in both types of patients. It is concluded that the major form of hereditary hyperekplexia is associated with impaired transmission in glycinergic reciprocal inhibitory pathways. The findings demonstrate the importance of reciprocal inhibition for the muscle tone in man, and it is suggested that the impaired reciprocal inhibition seen in patients with a defect in the glycine receptor may contribute to the increased muscle stiffness that is observed in these patients.