Veranderingen in de blink reflex ten gevolge van zuurstoftherapie voor actieve clusterhoofdpijn.

Rationale:

In order to further unravel the pathophysiology of cluster headache, we want to determine the location at which oxygen exerts its pain reducing effects in humans. We hypothesize a neurogenic effect of oxygen at brainstem level. As a substitute for measurement of impairment of parasympathetic outflow and to determine the influence of interneurons on the trigemino-facial reflex arch, we will look at the effect of oxygen on medullary interneurons by using the ‘nociception specific’ blink reflex.



Objective:

The primary objective is to measure R2 latencies, amplitude, duration and area of the electrically evoked ‘nociception specific’ blink reflex before and after treatment with oxygen at a flow rate of 12 L/min during a cluster headache attack.



Study design:

Repeated measures: The ‘nociception specific’ blink reflex will be measured before a spontaneous cluster headache attack (without and with oxygen treatment), shortly after the onset of the attack and 12-15 minutes after the start of treatment with 100% oxygen.



Study population:

Episodic cluster headache patients in a cluster period and chronic cluster headache patients, aged 18-70 years, of both genders.



Intervention:

All patients will be treated with 100% percent oxygen at a flow rate of 12 L/minute, given 3 minutes after pain onset for 15 minutes, using a non-rebreathing facial mask.



Main study parameters/endpoints:

The main study endpoints are differences in R2 latency, amplitude, duration and area measured on both sides between the time points: before a cluster headache attack (without oxygen treatment), immediately after start of the cluster headache attack and after 12-15 minutes of oxygen treatment for the cluster headache attack.
The secondary study endpoints are differences in change of R2 latencies, amplitudes, durations and areas in the 12-15 minutes of oxygen treatment between the groups: clear responders (reduction of pain of at least 50% within 15 minutes after the start of oxygen inhalation) and non-responders plus moderate responders (reduction of pain of less than 50% within 15 minutes after the start of oxygen inhalation); differences in R2 latency, amplitude, duration and area at the aforementioned 3 time points between the symptomatic and asymptomatic side; differences in R2 latency, amplitude, duration and area before a cluster headache attack without and with oxygen treatment.



Nature and extent of the burden and risks associated with participation, benefit and group relatedness:

Before starting the first blink reflex measurement patients will have to fill in a questionnaire. • Patients will undergo at least four blink reflex measurements during one visit: the blink reflex will be elicited every 2 hours before the onset of a cluster headache attack without oxygen treatment, once before the onset of a cluster headache attack during oxygen treatment, at the onset of the cluster headache attack and 12-15 minutes after the start of oxygen treatment. The stimulations during the blink reflex measurements will produce a pinprick-like pain. • During the first 3 minutes of the cluster headache attack (i.e. during the first blink reflex measurement during the cluster headache attack) the patient will not receive oxygen treatment. However, we assume that this reflects the patient’s situation at home. • Oxygen entails a fire hazard. Very rare side effects of oxygen treatment are pleuritis and respiratory distress syndrome. • The VAS pain score (of 0-10) will be asked for at the onset of the cluster headache attack, at 3 minutes after the onset of the cluster headache attack (i.e. at the start of oxygen treatment) and at 15 and 18 minutes after the onset of the cluster headache attack.
The study will not provide an immediate benefit for the individual participating patient. This study will contribute to a better understanding of cluster headache pathophysiology. A better understanding of the disease pathophysiology will lead to more targeted and therefore probably more effective treatment or applications of treatment in the future, leading to better pain relief and/or prevention of pain.

N/A

Every 2 hours before cluster headache (CH) attack, immediately after CH attack onset and after 12-15 min. of oxygen treatment for CH attack.

100% oxygen at 12 L/min, will be given 3 min. after cluster headache attack onset for 15 min. Blink reflexes will be measured directly after cluster headache attack onset and after 12 min. of oxygen treatment.