A 60-year-old diabetic woman presented to the emergency department with lower-limb weakness and loss of sensation that had developed gradually over a year along with upper back pain. A history of trauma, tuberculosis, fever, weight loss, and bladder and bowel incontinence were all ruled out. There was no prior history of hospitalisation or medical treatment. The patient was fully conscious with a Glasgow coma score (GCS) of 15. Mild tenderness at the D4-D5 vertebral level with spastic paraplegia (power 0/5) with no upper extremity weakness and an exaggerated deep tendon reflex was noted on clinical examination. A further neurological examination revealed that pinprick and fine touch sensations were reduced below the level of D5, but posterior column sensations were intact. The magnetic resonance imaging (MRI) revealed a well-defined extradural, intensely enhancing right-sided ventrodorsal semicircular lesion causing severe spinal cord impingement (Figure 1) as well as a periaortic soft tissue mass (Figure 2).
The lesion was found to have a ventral extension from D1-D5 and a dorsal extension from D2-D6. The CT aortogram revealed diffuse thickening and enhancement of the ascending aorta, aortic arch, and descending aorta, with periaortic mass measuring up to 13 mm (Figure 3).
The proximal parts of the aortic arch vessels, bilateral renal arteries, and common iliac vessels were also thickened with luminal narrowing. A repeat clinical examination revealed a lower radial pulse intensity on the right upper limb compared to the left, with a systolic pressure difference of 20 mmHg. There was no tenderness or thickening of the bilateral superficial temporal arteries on palpation. Preoperative investigations revealed elevated erythrocyte sedimentation rate (ESR) (74 mm/hr) and C-reactive protein (2.9 mg/dl) with elevated neutrophils (88% on the differential blood count). Anti-dsDNA (18 IU/ml), anti-cardiolipin immunoglobulin G (IgG) (<2 U/ml), and rheumatoid factor (8.6 IU/ml) levels were normal. The rapid plasma reagin test was non-reactive, and anti-nuclear antibody results were negative. The viral markers (HIV, hepatitis B surface antigen (HBsAg), and hepatitis C virus (HCV)) were also non-reactive. Based on large vessel vasculitis features on imaging and European League Against Rheumatism (EULAR) diagnostic criteria for TA, a probable diagnosis of TA leading to compressive thoracic myelopathy was made, and the patient was immediately scheduled for surgical decompression due to severe spinal cord compression. A biopsy of the lesion was performed after transpedicular decompression at the D4-D5 level, followed by decompressive laminectomy (D1-D6) and posterior fusion with transpedicular screws. Histopathological examination of the tissue revealed a dense chronic inflammatory infiltrate composed of foamy histocytes, lymphocytes, and plasma cells (Figure 4).
The acid-fast bacilli stain was negative, and there was no evidence of necrosis. The probability of IgG4-related disease was also ruled out, as the immunohistochemistry staining of the biopsy specimen revealed <10% IgG4 plasma cells with absent storiform fibrosis and phlebitis. Because there was no improvement in the patient's neurological status in the immediate postoperative period, the patient was advised to undergo rehabilitation before being discharged from the hospital. To treat large vessel vasculitis caused by TA, the rheumatologist prescribed oral prednisolone 20 mg/day and mycophenolate mofetil 1500 mg/day. The immunotherapy was gradually tapered over six months, and a six-month follow-up MRI revealed a near-complete reduction in the extradural mass (Figure 5) as well as full neurological recovery (Power 5/5).