Case 1
History
A 74-year-old male, who complained of left facial palsy, diplopia, and dysphagia, was referred to our department. The neurological examination revealed peripheral facial palsy of House-Brackman grade III and positive curtain sign at the left soft palate; he presented with no other neurological deficit such as external ocular movement disturbance, hearing loss, limb paralysis, or ataxia. Screening MR imaging scan including time-of-flight (TOF) MR angiography had revealed infarction in the left cerebellar hemisphere and occlusion of the left vertebral artery (VA), both of which mimicked VA dissection (Fig. 1). His neurological symptoms were deteriorating through conservative treatment, and he was admitted to our department.
He had a history of autoimmune pancreatitis and underwent whole-body 18 F-fluorodeoxyglucose positron emission tomography integrated with computed tomography scan, revealing elevated glucose intake at and enlargement of the pancreas, kidney, and bilateral submandibular glands. Serum IgG4 level was markedly elevated (2410 mg/dL). These findings were consistent with IgG4-RD.
Vessel wall imaging
The patient underwent 3D T1-weighted black blood VWI with and without contrast agent using a 3 tesla MR unit (MAGNETOM Skyra, Siemens Healthcare, Erlangen, Germany) with 32-channel head coil. The imaging parameters were as follows: TR = 1000 ms, TE = 11 ms, field of view = 180 × 180 mm, matrix = 320 × 320, slice thickness = 0.56 mm (0.56 mm isotropic voxel), bandwidth = 380 Hz/pixel, acceleration factor = 2 × 2, and scan time = 5 m 34 s. To improve imaging contrast between the vessel wall and cerebrospinal fluid, the imaging sequence was prepared by DANTE prepulse [13,14,15]. The parameters of this prototype sequence were as follows: 148 pulse trains, RF pulse flip angle = 10°, and pulse spacing = 1.1 ms with a spoiler gradient applied along the three axes. Three-dimensional gradient echo imaging was performed using the volumetric interpolated breath-hold examination (VIBE) technique to produce another set of 3D anatomical images. Its parameters were TE/TR = 2.29/6 ms, FOV = 230 × 230 mm, matrix = 250 × 250, slice thickness = 0.9 mm (0.9 mm isotropic voxel), receiver bandwidth = 220 Hz/pixel, acceleration factor = 2, and scan time = 2 min 24 s.
VWI revealed lesions not only at the left intracranial VA but also at the supra-clinoid portion of the bilateral internal carotid arteries (ICAs) (Fig. 2). The latter lesion had not been recognized with MR angiography. All these lesions were characterized as nearly-circumferential mural thickening with iso-intensity on non-contrast T1-weighted image, which was homogeneously enhanced with contrast agent (Fig. 2). These findings were incompatible with dissection and were considered to indicate the arteriopathy associated with IgG4-RD. The outer diameter of the ICA was expanded at the supra-clinoid portion, while the luminal space remained intact despite mural thickening (Fig. 2 A and C). A similar expansive remodeling was observed in the left VA at the level below the occlusion (Fig. 2B and D); however, both outer and inner diameters were severely narrowed at the occlusion site.
T1-weighted contrast enhanced MR imaging scan had also revealed enhanced mass lesions at the bilateral lacrimal glands and at the geniculate ganglion of the left facial nerve. The patient’s neurological symptoms were attributable to these lesions and/or direct inflammation spreading from the arteritis to the cranial nerves. Antiplatelet agent was not administered. He did not undergo biopsy of the intracranial vessel wall because the procedure is highly invasive.
He was referred to immunologists, and corticosteroid treatment (prednisolone 40 mg per day) was started. This treatment was tolerated and no adverse event occurred. His symptoms were resolved shortly after the treatment. Serum IgG4 level was significantly reduced (185 mg/dL) 4 months after treatment initiation. VWI performed at the same period revealed decreased mural thickening and enhancement in the bilateral supra-clinoid ICAs (Fig. 2E). A similar improvement was partly observed in the left VA (Fig. 2 F); however, the occlusion itself remained unrestored.
