Basal ganglia T1 hyperintensity in LGI1-autoantibody faciobrachial dystonic seizures

Abstract

Objective: To characterize the clinical features and MRI abnormalities of leucine-rich glioma-inactivated 1 (LGI1)-autoantibody (Ab) faciobrachial dystonic seizures (FBDS).

Methods: Forty-eight patients with LGI1-Ab encephalopathy were retrospectively identified by searching our clinical and serologic database from January 1, 2002, to June 1, 2015. Of these, 26 met inclusion criteria for this case series: LGI1-Ab seropositivity and FBDS. In a separate analysis of all 48 patients initially identified, the MRIs of patients with (n = 26) and without (n = 22) FBDS were compared by 2 neuroradiologists blinded to the clinical details.

Results: The median age of the 26 included patients was 62.5 years (range 37-78); 65% were men. FBDS involved arm (26), face (22), and leg (12). Ten were previously diagnosed as psychogenic. Ictal EEGs were normal in 20 of 23 assessed. Basal ganglia T1 and T2 signal abnormalities were detected in 11 patients (42%), with excellent agreement between neuroradiologists (κ scores of 0.86 and 0.93, respectively), and included T1 hyperintensity alone (2), T2 hyperintensity alone (1), or both (8). The T1 hyperintensities persisted longer than the T2 hyperintensities (median 11 weeks vs 1 week, p = 0.02). Improvement with immunotherapy (18/18) was more frequent than with antiepileptic medications (10/24). A separate analysis of all 48 patients initially identified with LGI1-Ab encephalopathy showed that basal ganglia MRI abnormalities were present in 11 of 26 with FBDS but not present in those without FBDS (0/22) (p < 0.001). In contrast, mesial temporal MRI abnormalities were less common among those with FBDS (42%) than those without (91%) (p < 0.001).

Conclusions: Basal ganglia T1 hyperintensity is a clinically useful MRI biomarker of LGI1-Ab FBDS and suggests a basal ganglia localization.

Figure 1. MRI head in faciobrachial dystonic seizures

(A) Axial fluid-attenuated inversion recovery image from patient 3 in table 2 shows T2-weighted hyperintensity within the right caudate nucleus (A.a, arrow), and T1-weighted images prior to gadolinium administration reveal T1 hyperintensity in the caudate and upper putamen on axial images (A.b, arrow). Restricted diffusion is notable on diffusion-weighted images (A.c, arrow) and corresponding apparent diffusion coefficient images (A.d, arrow). (B) Axial T1-weighted images prior to gadolinium administration from patient 2 in table 2 reveal an initial T1 hyperintensity in the left putamen on axial (B.a, arrow) and sagittal images (B.b, arrow). (C) Coronal T1-weighted images prior to gadolinium administration from patient 5 in table 2 reveal T1 hyperintensity in the left globus pallidus and putamen (arrow).

Figure 2. Evolution of MRI abnormalities in faciobrachial dystonic seizures

Axial fluid- attenuated inversion recovery (FLAIR)-weighted images from patient 4 in table 2 reveal left putamen and globus pallidus T2 hyperintensity (A.a, arrow) with T1 hyperintensity prior to gadolinium administration in the left putamen (A.b, arrow). The T2 hyperintensity resolved on follow-up FLAIR image (B.a), but T1 hyperintensity persisted (B.b, arrow); both resolved on further follow-up images (C.a, C.b). During a clinical relapse, a right-sided FLAIR T2 hyperintensity appeared (D.a, arrow) with concurrent T1 hyperintensity on pregadolinium images (D.b, arrow). The T2 hyperintensity subsequently resolved (E.a) prior to the T1 hyperintensity (E.b, arrow). FBDSz = faciobrachial dystonic seizures.

Figure 3. EEG demonstrating ictal seizure discharges in a patient with faciobrachial dystonic seizures

The EEG of a 56-year-old woman with faciobrachial dystonic seizures is shown. The EEG was unchanged at the onset of her dystonic seizures, manifested by bilateral upper extremity (bil UE) extension followed by left hand dystonia lasting 12 seconds. The EEG eventually showed rhythmic seizure activity over the left temporal region (arrows), which persisted beyond termination of the left hand dystonia.