Occipital nerve stimulation decreases attack frequency of intractable chronic cluster headache: Lancet

Chronic cluster headaches are a type of painful headaches that occur in regular patterns of cluster periods. It is characterized by migraine-like nausea and aura. It disturbs one's sleep at night as it generally causes severe pain in or around one eye on one side of the head. These episodes of frequent attacks are also called cluster periods, which can last from weeks to months. Occipital nerve stimulation (ONS) has shown promising results in small uncontrolled trials in patients with medically intractable chronic cluster headache (MICCH).

A study was conducted by a group of researchers from the Netherlands, to demonstrate if occipital nerve stimulation could prove to be an efficient treatment for patients with medically intractable chronic cluster headache.

The researchers conducted a controlled clinical trial at a total of six hospitals, four hospitals in the Netherlands, one hospital in Belgium, one in Germany, and one in Hungary. After 12 weeks' baseline observation, a total of 150 patients were enrolled with a history of being non-responsive to at least three standard preventive drugs between October 12, 2010, to December 3, 2017. They were randomly allocated to treatment 131 (87%) to treatment for 24 weeks; out of which 65 (50%) patients were assigned to 100% Occipital nerve stimulation and 66 (50%) were assigned to 30% Occipital nerve stimulation. One of the 66 patients assigned to 30% ONS was not implanted and was therefore excluded from the intention-to-treat analysis. As occipital nerve stimulation causes paraesthesia, preventing masked comparison versus placebo, they compared high-intensity versus low-intensity occipital nerve stimulation, which is hypothesized to cause similar paraesthesia, but with different efficacy. The primary outcome was the weekly mean attack frequency in weeks 21-24 compared with baseline across all patients and if a decrease was shown, to show a group-wise difference.

The findings of the study are as follows:

· Median weekly mean attack frequencies in the total population decreased from baseline to 7·38) in 21-24 weeks, with a median change of -5·21 attacks per week.

· In the 100% occipital nerve stimulation group, mean attack frequency decreased from 17·58 (9·83 to 29·33) at baseline to 9·50 (3·00 to 21·25) at 21-24 weeks.

· While in the 30% occipital nerve stimulation group, mean attack frequency decreased from 15·00 (9·25 to 22·33) to 6·75 (1·50 to 16·50; -6·50, -10·83 to -0·08).

· The difference in median weekly mean attack the frequency between groups at the end of the masked phase in weeks 21-24 was -2·42

· In the masked study phase, adverse events occurred more in the 100% occipital nerve stimulation group (n=129) as compared to 30% occipital nerve stimulation group (n=95)

· The most common adverse events were local pain, impaired wound healing, neck stiffness, and hardware damage.

· All the adverse events were expected but 17 with 100% occipital nerve stimulation group and 8 with 30% occipital nerve stimulation group were labeled as serious, as they required hospitalization.

Thus, the researchers concluded that both 100% and 30% occipital nerve stimulation substantially reduced attack frequency and were safe as well as well-tolerated. Hence, future studies should focus on optimizing stimulation protocols and disentangling the underlying mechanism of action.

Reference:

Safety and efficacy of occipital nerve stimulation for attack prevention in medically intractable chronic cluster headache (ICON): a randomized, double-blind, multicentre, phase 3, electrical dose-controlled trial by Wilbrink L et. al published in The Lancet Neurology journal.

DOI: 10.1016/S1474-4422(21)00101-0