Secondary SUNCT Syndrome with Transformation from Trigeminal Neuralgia

Sir,

Trigeminal neuralgia and short-lasting, unilateral, neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) are classified as distinct disorders.[1] Most of SUNCT are idiopathic, but there are some casies in the previous report that are secondary to intracranial neoplasm,[2,3,4] most of which are pituitary tumors and no reports of vestibular schwannoma. Herein, we report a short case of SUNCT syndrome and trigeminal neuralgia secondary to cerebellopontine angle (CPA) vestibular scwannoma.

A 45-year-old woman presented with a chief complaint of paroxysmal pain in the right maxillary region. The initial onset of the patient's chief complaints occurred 3 months earlier, and she noticed pain when she touched her tongue to the palate gingiva. The primary care dentist administered splint therapy and loxoprofen (Loxonin®) 50 mg/day after diagnosing temporomandibular disorder (TMD), which did not alleviate her symptoms. One week before presenting to our clinic, the patient developed severe pain in the entire right upper jaw and temporal region, lasting a few minutes. Exacerbations with lacrimation and sweating of the face occurred 1–2 times/day. Subsequently, the patient complained of hearing loss and double vision on the right side. A clinical diagnosis of trigeminal neuralgia TN was made based on your description of the pain, including type, location and triggers of pain, and the patient was prescribed oral carbamazepine (Tegretol®) 100 mg twice daily (200 mg/day), which resulted in complete remission of pain attacks and autonomic signs. Brain magnetic resonance imaging (MRI) revealed a mass compressing the pons and right fifth cranial nerve complex [Figure 1a-d]. The patient was referred to a neurosurgeon who removed the tumor under general anesthesia; orofacial pain disappeared immediately. The histopathological diagnosis was a vestibular schwannoma.

Figure 1.

MRI axial T1 after contrast agent (a), and heavily T2 2D image (b). The mass compresses the ipsilateral trigeminal root at the CPA. The size of the tumor is 17 × 15 mm. MRI of the coronal plane with T1 contrast (c). MRI of the sagittal plane with T1 contrast (d). Yellow and white arrows indicate tumor and the cerebral blood vessels, respectively

From April 1990 to February 2022, 19 cases of secondary SUNCT due to neoplasm have been reported so far. Of these, five cases were pituitary adenoma, four cases were pituitary macroadenoma, three cases were pituitary macroadenoma, and the one case was pilocytic astrocytoma, leiomyosarcoma, epidermoid tumor, cyst, meningioma, pulmonary metastases, angioma, and our case (vestibular schwannoma), respectively Table 1.[2,3,4] Regarding the location of the neoplasm confirmed by MRI, the cavernous sinus were observed in five cases, three in the pons-CPA, two in the carotid artery, two in the ocular region, and one in the frontotemporal area. Three pituitary microadenomas and three pituitary adenomas showed no extension, but the remaining one case was expanding in MRI.[2,3,4] To our knowledge, this is the first case reporting a SUNCT syndrome probably caused by vestibular schwannoma in CPA. Initially, classical trigeminal neuralgia appeared in the second division, which gradually changed to atypical trigeminal neuralgia, eventually becoming SUNCT syndrome, suggesting secondary SUNCT syndrome with transformation from trigeminal neuralgia. From the MRI sagittal section, since the first branch of the trigeminal nerve is located between the mass and the cerebral blood vessels, we assume that the tumor compresses the trigeminal nerve which was compressed by the artery opposite region. The pathophysiology of primary and secondary SUNCT cases may be related to compression of the trigeminal nerve, and the process of SUNCT is activated.[5]

Table 1.

Clinical features of 20 patients with SUNCT attributed to neoplasm

Disease	Patient no.	Age at onset (years)	SEX	Duration (seconds)	Frequency T (per day)	rigger	Pain side	Focus location in MRI/CT	Effective treatment
Pituitary adenoma	1	46	M	15-120	3-6	Yes	L	L cavernous sinus	CAB
	2	22	F	<60	5-10	Yes	L	No extension	CAB
	3	26	M	60	2-8	N/A	L	No extension	Surgery
	4	18	F	30	5-10	No	R	No extension	LMT
	5	26	M	180-240	4	No	L	extension	CAB
Pituitary macroadenoma	6	26	M	20-30	1-6	Yes	R	R cavernous sinus and carotid artery	BCT
	7	33	M	10	1-10	Yes	L	L cavernous sinus	DA
	8	35	F	60-120	40	Yes	R	R cavernous carotid artery	LMT
	9	27	F	15-30	N/A	Yes	L	L cavernous sinus	Radiotherapy
Pituitary microadenoma	10	24	F	15-30	10-30	Yes	L	No extension	Surgery
	11	28	M	20-30	100-200	N/A	R	No extension	Surgery
	12	33	M	60-120	30	N/A	L	No extension	Surgery
angioma	13	62	M	60	15-23	YES	R	R pons-CPA	CA
Leiomyosarcoma	14	45	M	60-120	10-15	Yes	L	L cavernous sinus	N/A
Pilocytic astrocytoma	15	11	F	30-60	20	No	R	R pons-CPA	Surgery
Epidermoid tumor	16	33	M	30-60	240	Yes	L	L pons-CPA	Surgery
Cyst	17	23	F	10-60	20-30	Yes	R	R ocular region	Surgery
Pulmonary metastases	18	69	F	60-120	50-70	Yes	R	R ocular region	Radiotherapy
Meningioma	19	81	F	N/A	60	No	L	L frontotemporal infiltrative growing	GBP
Our casetvestibular schwannoma)	20	45	F	60-120	1-2	Yes	R	R pons-CPA	Surgery

BCT = bromocriptine, CA = Carbamazepine, CAB = cabergoline, CPA = cerebellopontine angle, CT = computed tomography, DA = dopamine, GBP = gabapentin, LMT = lamotrigine, MRI = magnetic resonance, N/A = not applicable

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Conflicts of interest

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