Clinical and MRI phenotypes of sarcoidosis-associated myelopathy

Abstract

Objective: To determine the characteristic clinical and spinal MRI phenotypes of sarcoidosis-associated myelopathy (SAM), we analyzed a large cohort of patients with this disorder.

Methods: Patients diagnosed with SAM at a single center between 2000 and 2018 who met the established criteria for definite and probable neurosarcoidosis were included in a retrospective analysis to identify clinical profiles, CSF characteristics, and MRI lesion morphology.

Results: Of 62 included patients, 33 (53%) were male, and 30 (48%) were African American. SAM was the first clinical presentation of sarcoidosis in 49 patients (79%). Temporal profile of symptom evolution was chronic in 81%, with sensory symptoms most frequently reported (87%). CSF studies showed pleocytosis in 79% and CSF-restricted oligoclonal bands in 23% of samples tested. Four discrete patterns of lesion morphology were identified on spine MRI: longitudinally extensive myelitis (n = 28, 45%), short tumefactive myelitis (n = 14, 23%), spinal meningitis/meningoradiculitis (n = 14, 23%), and anterior myelitis associated with areas of disc degeneration (n = 6, 10%). Postgadolinium enhancement was seen in all but 1 patient during the acute phase. The most frequent enhancement pattern was dorsal subpial enhancement (n = 40), followed by meningeal/radicular enhancement (n = 23) and ventral subpial enhancement (n = 12). In 26 cases (42%), enhancement occurred at locations with coexisting structural changes (e.g., spondylosis).

Conclusions: Recognition of the clinical features (chronically evolving myelopathy) and distinct MRI phenotypes (with enhancement in a subpial and/or meningeal pattern) seen in SAM can aid diagnosis of this disorder. Enhancement patterns suggest that SAM may have a predilection for areas of the spinal cord susceptible to mechanical stress.

Figure 1. Longitudinally extensive myelitis, short tumefactive myelitis, and spinal meningitis/meningoradiculitis

(A) In this patient, intramedullary high T2 signal spans the cervical and upper thoracic spinal cord (A.a = sagittal T2), with extensive enhancement in a dorsal subpial distribution, indicated by the yellow arrow in A.b and the yellow dotted line in A.c (A.b = sagittal T1 fat saturation postgadolinium, A.c = axial T1 postgadolinium, with axial location indicated by the yellow line in panel B). (B) This longitudinally extensive myelitis lesion spans from C2 to C7 (B.a = sagittal T2), again with extensive dorsal subpial enhancement, indicated by the yellow arrow in B.b (B.b = sagittal T1 postgadolinium). On axial T1 postcontrast enhancement resembles the trident sign (outlined by the yellow dotted line), without central canal enhancement (B.c with axial location indicated by the yellow line in panel B.b). (C) In this patient, a bulky lesion is demonstrated in the lower thoracic spinal cord, highlighted by the yellow circle (C.a = sagittal T2), with associated dorsal-predominant patchy enhancement, outlined by the yellow dotted line (C.b = sagittal T1 postgadolinium). The radiology report (before diagnosis of sarcoidosis) suggested an intrinsic spinal cord tumor as the most likely diagnosis. (D) Bulky pachymeningeal disease can be seen in the cervical region in this patient on sagittal T1 postgadolinium sequence. (E) Enhancement (highlighted by yellow arrows) is present in a nodular leptomeningeal pattern (sagittal T1 fat saturation postgadolinium image of the cervical region) in a patient with spinal meningitis. (F) Avid nerve root enhancement is present in the cervical ventral and dorsal nerve roots (F.a = axial T1 postgadolinium image at the level of C5, with yellow arrows indicating enhancement of the left anterior, left posterior, and right posterior spinal nerve roots) and in the cauda equina (F.b = axial T1 postgadolinium at the level of L1, with the yellow area indicating the enhancing nerve roots) of this patient.

Figure 2. Inflammation of spinal cord sarcoidosis occurring in areas susceptible to mechanical stress

(A and B) The lesion pattern of anterior myelitis with ventral subpial enhancement occurring focally in areas of the spinal cord overlying disc degenerations is demonstrated in 2 patients here. In patient A (A.a = sagittal T2, A.b = sagittal T1 fat saturation postgadolinium), focal enhancement occurs in the spinal cord in close relationship with 4 bulging thoracic discs (arrows). A similar pattern is demonstrated in patient B (B.a = sagittal T2, B.b = sagittal T1 postgadolinium), with focal enhancement centered over 2 areas of disc degeneration (arrows). In all cases with this lesion pattern, patients' MRI findings and clinical symptoms improved with medical treatment of sarcoidosis, without any requirement for spinal surgery. (C and D) In patients with other lesion types, enhancement also frequently occurred in close relationship with coexisting structural changes such as degenerative disc disease or spinal stenosis. Two patients with longitudinally extensive myelitis are demonstrated here, with the areas of ventral and dorsal subpial enhancement in the spinal cord occurring in close proximity to cervical degenerative changes. In patient C (C.a = sagittal T2, C.b = sagittal T1 fat saturation postgadolinium), avid enhancement is centered in the region of the cervical cord where the spinal canal is tightest, and the enhancement pattern appears to demonstrate both the linear dorsal subpial enhancement typical of sarcoidosis-associated myelopathy (SAM) and the transverse pancake-like enhancement of spondylotic myelopathy (arrows). The imaging findings suggest the coexistence of SAM and spondylotic myelopathy in this patient. In patient D (D.a = sagittal T2, D.b = sagittal T1 postgadolinium), with degenerative changes throughout the cervical spinal column, enhancement of spinal cord sarcoidosis is pronounced in this region (arrows).

Figure 3. Lesion location and time to diagnosis according to the lesion pattern

(A) The location of lesions involving the parenchyma of the spinal cord (longitudinally extensive myelitis, short tumefactive myelitis, and anterior myelitis with disc degeneration) is illustrated here, with each patient represented separately. Longitudinally extensive myelitis was predominantly cervicothoracic in distribution, whereas anterior myelitis with disc degeneration was essentially restricted to the thoracic region. (B) Time from symptom onset to diagnosis is recorded here, categorized by the lesion pattern. Only patients without a preexisting diagnosis of sarcoidosis (i.e., in whom myelopathy was the first manifestation of sarcoidosis) are included in this graph (49 of 62 patients, 79%).