Short-lasting unilateral neuralgiform headache attacks with ispilateral facial flushing is a new variant of paroxysmal extreme pain disorder.

Background: We encountered a 5-year-old girl who had short-lasting, severe, unilateral temporal headaches with ipsilateral lacrimation, nasal congestion and rhinorrhoea, and facial flushing after severe attacks. Family history revealed similar short-lasting, severe headaches in an older brother, younger sister, mother, maternal aunt, and maternal grandfather's brother.

Methods: We performed routine laboratory examinations and electrophysiological and radiological studies for three children, and whole-exome sequencing to determine the genetic causality in this family.

Results: Focal hyperperfusion of the right trigeminal root entry zone was seen during a right-sided attack in one child, while left-sided temporal headache attacks were provoked by bilateral electrical stimulation of the upper extremities in another. We identified a novel SCN9A mutation (NM_002977: c.5218G>C, p.Val1740Leu) in all affected family members, but not in any of the unaffected members. SCN9A encodes the voltage-gated sodium-channel type IX alpha subunit known as Na(v)1.7.

Conclusions: Gain-of-function mutations in Na(v)1.7 are well known to cause paroxysmal extreme pain disorder (PEPD), a painful Na-channelopathy characterized by attacks of excruciating deep burning pain in the rectal, ocular, or jaw areas. The SCN9A mutation suggests that our patients had a phenotype of PEPD with a predominant symptom of short-lasting, severe, unilateral headache.