We report 2 cases of NMDA receptor (NMDAR) encephalitis with classic signs and symptoms of encephalitis, but in whom Balint syndrome was a predominant manifestation in the evolution of the disease.
Patient 1, a 24-year-old woman, presented initially with catatonia, mutism, unusual anxiety, and generalized epileptic seizures. She received 3 months of intensive care. She had no psychosis, no movement disorders, no sleep disturbance, or dysautonomia. Cerebral MRI was normal. Based on a large workup (table) and positivity of CSF anti-NMDAR antibodies, a diagnosis of NMDAR encephalitis was made, and she was accordingly treated for encephalitis and seizures (table). No teratoma was detected. One year after disease onset, neuropsychological assessment found deficits in executive functions (working memory, planning, and mental flexibility), constructive apraxia, and left spatial neglect; Balint syndrome was not assessed at this time. She was evaluated again 2 years after disease onset because of visual complaints, such as misreaching when grasping objects and difficulty to judge distances. Ophthalmologic examination and visual field were normal. Neurologic examination highlighted difficulties to reach and grasp a pen introduced in the patient's peripheral visual fields related to bilateral optic ataxia1; lateralized spatial attention disorder attested by a rightward bias in manual line bisection and left omissions related to left hemineglect; and partial descriptions of complex pictures and embedded shapes, inability to detect the contour of dotted lines and to perform visual labyrinth tests, and inability to enumerate dots with a revisiting phenomenon consistent with simultanagnosia.2 Eye movements were normal. A full Balint syndrome was therefore diagnosed on the association of optic ataxia, psychic paralysis of gaze (simultanagnosia), and lateralized disorder of attention (left hemineglect).3 At this time, cerebral MRI remained normal, 18 fluorodeoxyglucose PET (18F-FDG PET/CT) found a mild left fronto-temporo-parietal and insular hypometabolism, and EEG found diffuse posterior slow waves without epileptiform abnormalities. She was treated with 2 new infusions of rituximab. Anticonvulsants were not modified.
Description of patients
Patient 2, a 19-year-old woman, presented with severe limb apraxia and aphasia, behavioral disorders such as emotional lability and psychomotor slowing, associated with signs of Balint syndrome. The patient had no movement disorders, no epileptic seizure, sleep disturbance, or dysautonomia. Based on a large workup (table) and the positivity of CSF anti-NMDAR antibodies, a diagnosis of NMDAR encephalitis was made, and she was accordingly treated (table). No teratoma was found. At this time, cerebral MRI was normal, 18F-FDG PET/CT showed left temporo-occipito-parietal and bilateral insular hypermetabolism, and EEG found bilateral occipital and parietal slow waves without epileptiform abnormalities. She was re-evaluated 2 months after diagnosis at a rehabilitation center owing to the persistence of visual symptoms after recovery from aphasia and apraxia. Ophthalmologic examination and visual field were normal. Full Balint syndrome was diagnosed on the association of optic ataxia, simultanagnosia, and lateralized disorder of attention (left hemineglect) (table).2,3 Eye movements were normal. Balint syndrome recovered over the next 4 months.
Discussion
These 2 cases show the occurrence of Balint syndrome, in addition to other symptoms, in NMDAR encephalitis. Balint princeps description included optic ataxia, psychic paralysis of gaze (now called simultanagnosia), and lateralized disorder of attention (left spatial neglect), as observed in our 2 patients.3 Oculomotor apraxia as described later in addition to the triad was not observed in our 2 patients.
Balint syndrome is a reliable marker of bilateral parieto-occipital dysfunction. Accordingly, posterior slow waves were observed on EEG in our 2 patients. Such posterior EEG abnormalities have been previously reported in NMDAR encephalitis.4
While in most vascular or degenerative Balint syndrome, bilateral parieto-occipital hypo metabolism is reported; metabolic imaging in our patients showed different patterns. Occipital hypometabolism has been highlighted in NMDAR encephalitis, but other patterns have been described, such as focal and lateralized hypo- or hypermetabolism.5 Furthermore, seizures and psychotropic treatment may also contribute to the metabolic pattern variability.
The pathophysiologic mechanisms leading to these clinical, EEG, and imaging changes remain unclear. They could involve a direct pathogenic role of anti-NMDAR antibodies leading to NMDAR internalization and a consecutive change in neuronal activity.6 They could also involve a thalamo-cortical disconnection, as such damage in connectivity has been identified among users of ketamine, an NMDAR antagonist.7
Our clinical observations highlight that posterior tropism of functional and metabolic changes reported in NMDAR encephalitis4,5 can be symptomatic. Future studies are needed to assess the prevalence and pathophysiology of Balint syndrome in NMDAR encephalitis.
Study funding
No targeted funding reported.
Disclosure
A. Metzger, L. Pisella, A. Vighetto, and B. Joubert report no disclosures. J. Honnorat receives royalties from licensing fees to Athena Diagnostics, Euroimmun, and Ravo Diagnostika for a patent for the use of CV2/CRMP5 as diagnostic tests and received research support from CSL Behring France. C. Tilikete received travel funding and/or speaker honoraria from Santhera, Novartis, and Teva; served on the editorial boards of the Journal of Neuro-Ophthalmology, Frontiers in Neurology, and Neuro-ophthalmology; and receives publishing royalties from Elsevier Masson. V. Desestret reports no disclosures. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/NN.
Appendix 1 Author contributions
Footnotes
Funding information and disclosures are provided at the end of the article. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/NN.
The Article Processing Charge was funded by the Universite de Lyon.
- Received July 2, 2018.
- Accepted in final form November 8, 2018.
- Copyright © 2018 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.
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