Acta Neurologica Belgica (2021) 121:1093–1095
https://doi.org/10.1007/s13760-021-01735-w

LETTER TO THE EDITOR

Stroke‑like episodes with cerebellar ataxia as presenting
manifestation of adult‑onset anti‑N‑methyl d‑aspartate receptor
encephalitis: an unusual presentation
Rohan Mahale1 · M. K. Farsana · Anitha Mahadevan2 · Joydeep Mukherjee1 · Vathsala Lakshmi1 · M. Sandeep1 ·
Hansashree Padmanabha1 · Pooja Mailankody1 · Mathuranath Pavagada1
Received: 15 April 2021 / Accepted: 21 June 2021 / Published online: 3 July 2021
© Belgian Neurological Society 2021

Keywords Cerebellum · Ataxia · Stroke · NMDAR · Encephalitis
Dear Sir,
Anti-N-methyl d -aspartate (NMDA) receptor (antiNMDAR) encephalitis is an autoimmune encephalitis
which was first described in 2007 [1]. Memory deficits are
the most common clinical manifestation in patients with
anti-NMDAR encephalitis ≥ 45 years [2]. Cerebellar ataxia
and stroke-like episodes as presenting manifestation in lateonset anti-NMDAR encephalitis is rare. Hereby, we report
a 46-year-old male patient who presented with acute onset
cerebellar ataxia of 10-h duration. He had history of acute
onset left hemiparesis 15 days prior to present symptoms
and improved within 72 h. Brain magnetic resonance imaging (MRI) showed right striato–thalamo–capsular lesion
with contrast enhancement, multiple T2 hyperintense ovoid
subcortical white matter non-enhancing lesions. Angiography was normal. Cerebrospinal fluid (CSF) analysis showed
eight lymphocytes with normal protein and glucose. CSF
NMDAR antibodies were strongly positive. He was treated
with intravenous methylprednisolone and had complete
recovery.
A 46-year-old male patient had history of acute onset
holocranial headache 1 month prior to present admission
that lasted for 1–2 h with vomiting and blurred vision and
improved with analgesics. His blood pressure was normal
* Rohan Mahale
rohanmahale83@gmail.com
1

Department of Neurology, National Institute of Mental
Health and Neurosciences (NIMHANS), Bangalore 560029,
India

2

Department of Neuropathology, National Institute of Mental
Health and Neurosciences (NIMHANS), Bangalore 560029,
India

and was evaluated at local hospital with no specific diagnosis. He developed sudden onset left hemiparesis 15 days
later without sensory symptoms. His muscle power was 3/5
according to Medical Research Council grading. The hemiparesis lasted for 72 h and improved completely. He was
evaluated with brain MRI at local hospital and had right
striato-thalamocapsular lesion isointense on T1 and hyperintense on T2 with diffusion restriction suggestive of acute
infarct (Fig. 1). Time-of flight magnetic resonance angiography was normal. He was started on aspirin 150 mg with
atorvastatin 20 mg per day. 15 days later he developed acute
onset unsteadiness in walking with vertigo. It was continuous, required two persons to walk. He was having incoordination in both upper limbs. There was no speech disturbance. He presented to us with above symptoms. Systemic
examination was unremarkable. He was conscious, oriented
to time, place. Speech was normal. Fundus examination was
normal. Extraocular movements were normal with no nystagmus. Other cranial nerves were normal. Motor examination showed normal tone, power and reflexes. Sensory
examination was normal. He had bilateral finger-nose incoordination, dysdiadochokinesia and wide-based ataxic gait.
A possibility of cerebellar stroke was considered. Brain MRI
showed right striato-thalamo-capsular and corona radiata
lesion with contrast enhancement, multiple T2 hyperintense ovoid subcortical white matter non-enhancing lesions
(Fig. 2). There was no brainstem or cerebellar lesions. Angiography was normal. Complete blood counts, renal, hepatic
and thyroid function tests were normal. CSF analysis showed
eight lymphocytes with normal protein and glucose. Serum
and CSF anti-myelin oligodendrocyte glycoprotein and
aquaporin-4 antibodies were negative. Varicella deoxyribonucleic acid polymerase chain reaction in CSF was negative.
CSF NMDAR antibodies (cell based immunofluorescence

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Acta Neurologica Belgica (2021) 121:1093–1095

Fig. 1  Brain MRI T2 coronal
image A showing hyperintense
lesion in right striatothalamocapsular lesion (red arrow); B
axial diffusion-weighted image
shows diffusion restriction (red
arrow) (color figure online)

assay) were strongly positive. Scrotal ultrasonography did
not show testicular teratoma. Electroencephalography was
normal. He was treated with intravenous methylprednisolone
and had complete recovery. He was started on mycophenolate mofetil.
The common clinical manifestations of anti-NMDAR
encephalitis include cognitive dysfunction, abnormal behaviour, language/speech dysfunction, seizures, movement
disorders, dyskinesias, decreased level of consciousness,
autonomic dysfunction and central hypoventilation. It varies with age of onset of the disease. It is more neurological in
children and more psychiatric in adults [3]. The occurrence
of cerebellar ataxia in patients with anti-NMDAR encephalitis is almost exclusively found in children, and most frequently, it appears later in the disease in combination with
other symptoms.
Stroke-like episodes as a presenting manifestation of antiNMDAR encephalitis has not been reported. There are few
reports of cerebellar ataxia as presenting symptom in antiNMDAR encephalitis. Poorthuis et al. reported a 32-year-old
woman who had history of mature ovarian teratomas and
depression presented with cerebellar dysarthria, nystagmus,
limb incoordination and gait ataxia. Her CSF anti-NMDAR
antibodies were positive and serum anti-NMDAR antibodies were negative. The patient was treated with steroids and

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intravenous immunoglobulin with significant improvement
at 6 months [4]. Similarly, Wang et al. reported a 45-yearold man with 2-week history of ataxia followed by behavioural change, cognitive impairment. He had predominant
cerebellar ataxia. Brain MRI showed hyperintense lesions
in cerebellum, positive CSF anti-NMDAR antibodies and
negative serum anti-NMDAR antibodies. The patient was
treated with steroids and intravenous immunoglobulin with
significant improvement [5]. The cause for cerebellar ataxia
in NMDAR-encephalitis is postulated to be due to altered
NMDAR-mediated signalling [6].
Our patient had one episode of stroke involving right
thalamocapsular region causing left hemiparesis which
recovered within 3 days. Later he had sudden onset cerebellar ataxia with no lesions in cerebellum or brainstem. His
serum anti-NMDAR antibodies were negative but CSF antibodies was positive. He had good improvement with intravenous methylprednisolone.
Anti-NMDAR encephalitis has varied presenting manifestation which varies with the age of onset of the disease.
A possibility of anti-NMDAR encephalitis has to be considered in adult patients presenting with acute onset cerebellar
ataxia. This case adds to the few reports of acute cerebellar
ataxia as an initial manifestation of anti-NMDAR encephalitis. Stroke-like episodes has not been reported so far.

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1095

Fig. 2  Brain MRI T2 axial image A showing hyperintense lesion in
right corona radiata (red arrow); B axial fluid-attenuated inversion
recovery (FLAIR) image showing hyperintense lesion in right corona
radiata (red arrow) with multiple small subcortical hyperintense

lesions (yellow arrow); C MR angiography showing no occlusion or
stenosis; D axial diffusion-weighted image showing diffusion restriction (red arrow); E coronal t1-gadolinum enhanced image showing
contrast enhancement (red arrow) (color figure online)

Funding Nil.

4. Poorthuis MHF, van Rooij JLM, Koch AH, Verdonkschot AEM,
Leembruggen MM, Titulaer MJ (2019) Cerebellar ataxia as a presenting symptom in a patient with anti-NMDA receptor encephalitis. Neurol Neuroimmunol Neuroinflamm 6(4):e579. https://​doi.​
org/​10.​1212/​NXI.​00000​00000​000579
5. Wang B, Wang C, Ren H, Guan H, Guo S (2020) Cerebellar ataxia
as the initial symptom with lesions involving the cerebellum in
patient with anti-NMDAR encephalitis: a rare case report and
literature review. J Neuroimmunol 346:577293
6. Llansola M, Sanchez-Perez A, Cauli O, Felipo V (2005) Modulation of NMDA receptors in the cerebellum. 1. Properties
of the NMDA receptor that modulate its function. Cerebellum
4:154–161

Declarations
Conflict of interest Nil.

References
1. Dalmau J, Tüzün E, Wu HY, Masjuan J, Rossi JE, Voloschin
A et al (2007) Paraneoplastic anti-N-methyl-d-aspartate receptor encephalitis associated with ovarian teratoma. Ann Neurol
61:25–36
2. Zhang L, Liu X, Jiang XY, Wang YH, Li JM, Zhou D (2018) Lateonset anti-N-methyl-d-aspartate receptor encephalitis in China.
Epilepsy Behav 84:22–28
3. Titulaer MJ, McCracken L, Gabilondo I, Iizuka T, Kawachi I,
Bataller L et al (2013) Late-onset anti-NMDA receptor encephalitis. Neurology 81:1058–1063

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