SUNCT and SUNA: The Essentials

While it’s common for people with Migraine to also experience Primary Stabbing Headaches, SUNCT and SUNA can both be confused with these “ice pick” headaches. Primary Stabbing Headache, SUNCT, and SUNA all involve brief, stabbing pain. That is where the similarities end.

SUNCT and SUNA are not types of Migraine, but are classified as a type of headache disorder known as trigeminal autonomic cephalalgias, abbreviated as TAC. TACs are different than Migraine in the following ways:

• TACs don’t usually involve nausea, vomiting, light or sound sensitivity.
• TACs involve watering eyes, reddness of the eyes, runny or congested nose, or facial sweating.
• The pain of TACs is one-sided, usually concentrated in just one eye.
• The pain of TACs is characterized as burning or stabbing and is severe.
• TACs always involve head pain, where Migraine may or may not involve a headache.

SUNCT and SUNA are acronyms for:

• Short-lasting Unilateral Neuralgiform with Conjunctival injection and Tearing
• Short-lasting Unilateral Neuralgiform with cranial Autonomic symptoms

The names of these two headache disorders are quite descriptive. Once we understand the terms, we can also learn the primary symptoms.

• Short-lasting – 10 minutes or less (in the context of SUNCT and SUNA)
• Unilateral – one-sided
• Neuralgiform – resembling nerve pain
• Conjunctival injection – redness of the eye, as if injured
• Tearing – producing tears
• Autonomic – involuntary

Difference between the two:

• SUNCT includes BOTH redness of the eyes and tears
• SUNA may have EITHER one, but not both.

SUNCT and SUNA also have symptoms in common with:

• Cluster Headache
• Hemicrania Continua
• Paroxysmal Hemicrania
• Trigeminal Neuralgia

What’s different about these others?

• Primary Stabbing Headaches don’t involve the redness of the eyes, tears, nasal congestion, or runny nose. The pain can occur anywhere on the head.
• Cluster Headache attacks last at least 15 minutes and can continue for up to three hours.
• Hemicrania Continua attacks can last all day, with variable intensity.
• Paroxysmal Hemicrania attacks last for up to 30 minutes.

ICHD-3 Diagnostic Criteria:

Description:

Attacks of moderate or severe, strictly unilateral head pain lasting seconds to minutes, occurring at least once a day and usually associated with prominent lacrimation and redness of the ipsilateral eye.

Diagnostic criteria:

1. At least 20 attacks fulfilling criteria B–D
2. Moderate or severe unilateral head pain, with orbital, supraorbital, temporal and/or other trigeminal distribution, lasting for 1–600 seconds and occurring as single stabs, series of stabs or in a saw-tooth pattern
3. At least one of the following five cranial autonomic symptoms or signs, ipsilateral to the pain:
   1. conjunctival injection and/or lacrimation
   2. nasal congestion and/or rhinorrhoea
   3. eyelid oedema
   4. forehead and facial sweating
   5. miosis and/or ptosis
4. Occurring with a frequency of at least one a day¹
5. Not better accounted for by another ICHD-3 diagnosis.

Note:

During part, but less than half, of the active time-course of 3.3 Short-lasting unilateral neuralgiform headache attacks, attacks may be less frequent.

Comment:

Longer-duration attacks are characterized by multiple stabs or a saw-tooth pain pattern.

Two subtypes of 3.3 Short-lasting unilateral neuralgiform headache attacks are recognized: 3.3.1 Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) and 3.3.2 Short lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA). 3.3.1 SUNCT may be a subform of 3.3.2 SUNA, although this requires further study. Meanwhile, each is classified as a separate subtype, described below.

3.3.1 SUNCT and 3.3.2 SUNA can usually be triggered without a refractory period. This is in contrast to 13.1.1 Trigeminal neuralgia, which usually has a refractory period after each attack.

3.3.1 Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT)

Diagnostic criteria:

Attacks fulfilling criteria for 3.3 Short-lasting unilateral neuralgiform headache attacks, and criterion B below
Both of the following, ipsilateral to the pain:

1. conjunctival injection
2. lacrimation (tearing)

Comment:

The literature suggests that the most common mimic of 3.3.1 SUNCT is a lesion in the posterior fossa.

Patients have been described in whom there is overlap between 3.3.1 SUNCT and 13.1.1 Trigeminal neuralgia. Differentiation is clinically complex. Such patients should receive both diagnoses.

Patients with both 3.3.1 SUNCT and 3.1 Cluster headache have been reported; the pathophysiological significance of this overlap is yet to be determined.

3.3.2 Short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA)

1. Attacks fulfilling criteria for 3.3 Short-lasting unilateral neuralgiform headache attacks, and criterion B below
2. Only one or neither of conjunctival injection and lacrimation (tearing).

Sources:

1. International Headache Society (IHS) (2018). 3.3 Short-lasting unilateral neuralgiform headache attacks. (n.d.). Retrieved April 23, 2018, from https://www.ichd-3.org/3-trigeminal-autonomic-cephalalgias/3-3-short-lasting-unilateral-neuralgiform-headache-attacks/.
2. Lucas S. (11 September 2009). SUNCT (Short-lasting Unilateral Neuralgiform headache attacks with Conujuctival injection and Tearing). National Headache Foundation (11 September 2009). Retrieved September 25, 2016, from http://www.headaches.org/2009/09/11/case-studies-in-headache-archive-septemberoctober-2009/.
3. SUNCT Headache Information Page: National Institute of Neurological Disorders and Stroke (NINDS). National Institutes of Health (23 September 2015). Retrieved September 25, 2016, from http://www.ninds.nih.gov/disorders/sunct/sunct.htm
4. OUCH (UK). SUNCT Syndrome. OUCH (UK). Retrieved September 25, 2016, from https://ouchuk.org/sunct-syndrome