SUNCT & SUNA — Short-lasting Unilateral Neuralgiform Headache Attacks: Ultra-short, Ultra-frequent, and Difficult to Treat

The two conditions overlap in that both produce severe, brief, unilateral facial pain and both can be triggered by light touch. The key differences are: (1) SUNCT has associated autonomic features — eye redness and tearing — which trigeminal neuralgia does not; (2) SUNCT has a longer attack duration (seconds to 4 minutes vs the typical split-second stabs of classical TN); (3) SUNCT has no refractory period (successive stimulation triggers successive attacks), while TN has a brief refractory period; (4) SUNCT does not respond to carbamazepine as reliably as TN does; (5) TN responds to microvascular decompression in the majority of cases, while SUNCT responds much less predictably. The distinction matters because the treatments are different, and carbamazepine — first-line for TN — is not first-line for SUNCT.

Indomethacin produces absolute, complete pain relief in paroxysmal hemicrania through a mechanism that is not fully understood but appears to involve inhibition of a specific prostanoid pathway and nitric oxide-mediated processes that are uniquely relevant to PH. This mechanism is not operative in SUNCT/SUNA. The absence of response to indomethacin is, in fact, part of the diagnosis — if a patient's attacks completely resolve with indomethacin, the diagnosis is paroxysmal hemicrania, not SUNCT or SUNA.

Oxygen and sumatriptan work for cluster headache by mechanisms targeting the trigeminovascular pathway activation in cluster headache specifically. The neurobiological mechanisms underlying SUNCT/SUNA, while sharing the trigeminal-autonomic arc involvement, appear to differ in ways that make the cluster-specific treatments ineffective. The extremely short duration of SUNCT/SUNA attacks also means that even if a treatment were partially effective, the attack would often be over before the drug could take effect. The evidence base for both treatments in SUNCT/SUNA is negative.

Lamotrigine must be titrated very slowly to avoid the risk of rash (Stevens-Johnson syndrome), starting at 25mg/day and increasing by 25–50mg every 2 weeks to a target of 100–400mg/day. This means the titration to effective dose may take 4–8 weeks. At each dose level, the patient and clinician assess attack frequency to determine whether to continue or increase. Some patients show response at lower doses; others require the maximum tolerated dose. The slow titration is non-negotiable — faster titration increases the risk of the rare but potentially fatal Stevens-Johnson syndrome.

Triggers vary significantly between patients. The most commonly reported triggers are cutaneous: light touch to the face, jaw movement, eating (particularly chewing hard food), drinking cold or hot liquids, talking for prolonged periods, brushing teeth, neck movement, and eye movement. Identifying your personal triggers through observation is helpful — a headache diary can include a column for what preceded each attack. However, trigger avoidance alone does not constitute treatment and in many patients is insufficient to significantly reduce attack frequency given the spontaneous nature of most attacks.

For truly refractory SUNCT, several options are being explored in published case series and small trials. Greater occipital nerve block provides temporary relief in some patients and can be repeated. Occipital nerve stimulation — a semi-permanent neurostimulation device — has shown moderate benefit in published refractory cases. Deep brain stimulation of the posterior hypothalamus has been performed in a small number of severely affected patients in European centres with reported benefit. Calcitonin gene-related peptide (CGRP) pathway medications are being explored in TACs as a class; published evidence specifically for SUNCT/SUNA is limited but accumulating. At KIMS, patients with refractory SUNCT/SUNA are reviewed by the multidisciplinary headache and pain team to assess candidacy for these options.

SUNCT and SUNA are not life-threatening as primary conditions. However, the secondary causes that can produce a SUNCT/SUNA phenotype — including posterior fossa tumours — may be serious. This is why MRI is mandatory before a primary diagnosis is made. As a primary headache disorder, SUNCT/SUNA is profoundly disabling in severe cases but does not directly endanger life. The psychological burden of refractory chronic pain, however, is significant — access to pain psychology support is an important part of comprehensive management.

Yes, in the episodic form. The episodic pattern consists of active periods — typically weeks to months of daily attacks — separated by remissions of at least one month during which the patient is pain-free or near pain-free. These remissions are spontaneous and may last weeks to years. The chronic form, by definition, does not have remissions of more than one month. In the episodic form, treatment is typically continued during active periods and then reviewed during remission; many patients and clinicians choose to taper or stop preventive medications during extended remissions and restart when attacks recur.