Tic Versus TAC: Differentiating the Neuralgias (Trigeminal Neuralgia) from the Cephalalgias (SUNCT and SUNA)

Abstract

Trigeminal neuralgia, short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) and short-lasting unilateral neuralgiform headache attacks with autonomic symptoms (SUNA) are classified as distinct disorders in the International Classification of Headache Disorders 3 beta (ICHD-3 beta). SUNCT and SUNA are primary headache disorders included among the trigeminal autonomic cephalalgias. Trigeminal neuralgia is classified under painful cranial neuropathies and other facial pains. The classification criteria of these conditions overlap significantly which could lead to misdiagnosis. The reported overlap among these conditions has called into question whether they should be considered distinct entities or rather a continuum of the same disorder. This review explores the known overlap and how other features not included in the ICHD-3 beta criteria may better differentiate the "Tics" (trigeminal neuralgia) from the "TACs" (SUNCT and SUNA).

Tic, Triggering, and Tearing: From CTN to SUNHA

“…Interestingly, patients with V1 CTN showed progressive involvement of lower trigeminal branches in long‐term follow‐up . Similar late‐phase co‐involvement of V2 and V3 has not been reported in SUNCT series, but may be an interesting research focus. Is the spread of pain to trigeminal and extra‐trigeminal sites in SUNHAs a specific feature or part of the spectrum reflecting central sensitization with disease progression?…”

“…However, in contrast to CTN, where pain is exclusive to the trigeminal dermatomes, in SUNHAs, pain can occur outside the trigeminal dermatomes, such as the back of the head (28% of SUNCT and 22% of SUNA). 10,36 In the largest SUNCT and SUNA series published, 67% of SUNCT patients complained of pain in V1, 33% in V2, and none in V3, in contrast to 56% of SUNA patients who reported the maximal intensity of the pain in V1 and V2, and 33% in V3, suggesting a continuum with CTN in which the majority of the patients report attacks in V2, V3, or both. 10,18,37 Since CAS are not part of the diagnostic criteria of CTN, but are part of the comments, cases presenting with V1 pain distribution and lacrimation will be most likely diagnosed as SUNCT/SUNA and not as CTN.…”

“…10,26,45 The recognition of the varying pain patterns in SUNHA is significant, as the short attacks of pain could be mistaken for CTN and the longer-duration patterns of stab groups and sawtooth could be mistaken for CTN with background pain, CH, or paroxysmal hemicranias (PH). 36 Although according to ICHD-3 criteria, CTN duration has a cutoff at 2 minutes, 1 it is important to note that attack duration in CTN has not been thoroughly validated, and we continue to rely on patient reports. This reliance has significant potential for error but is still customary.…”

“…Primary location in SUNHAs is therefore similar to that seen in CTN. However, in contrast to CTN, where pain is exclusive to the trigeminal dermatomes, in SUNHAs, pain can occur outside the trigeminal dermatomes, such as the back of the head (28% of SUNCT and 22% of SUNA) …”

“…A mixture of short attacks on top of the typical plateau pattern termed “plateau‐like plus exacerbations” has also been described . The recognition of the varying pain patterns in SUNHA is significant, as the short attacks of pain could be mistaken for CTN and the longer‐duration patterns of stab groups and sawtooth could be mistaken for CTN with background pain, CH, or paroxysmal hemicranias (PH) …”