Journal of the Neurological Sciences 373 (2017) 46–47 Contents lists available at ScienceDirect Journal of the Neurological Sciences journal homepage: www.elsevier.com/locate/jns Letter to the Editor Akinetic mutism in a patient with acute infarcts in the bilateral substantia nigra Keywords: Akinetic mutism Acute infarct Substantia nigra Dear Editor-in-Chief, Akinetic mutism is defined as an extreme form of behavioral abnormalities relating to reduced activity and slowness [1]. The pathophysiology of akinetic mutism is explained by neural interruptions in the frontal-subcortical circuit that impact the dopaminergic system [2]. The frontal subcortical circuit includes the anterior cingulate cortex, anterior thalamus, caudate nucleus, globus pallidus, internal capsule, and substantia nigra [3]. Therefore, most patients displaying symptoms of akinetic mutism experience neurodegenerative or psychiatric conditions such as advanced Alzheimer's disease, Creutzfeld-Jakob's disease, Pick's disease, catatonic schizophrenia, or severe depression or stroke in the frontal-subcortical circuit [4]. However, there has been no report of akinetic mutism after acute infarcts in the bilateral substantia nigra. Here, we report a patient presented akinetic mutism as the sole manifestation of acute infarcts in the bilateral substantia nigra. A 71-year-old female presented with the sudden decrease of speech, movement, and emotional reactions for 2 days. She had a history of hypertension, diabetes, and old cerebral infarction without any fever, head trauma, dementia, or known exposure to neuroleptics. Her mental status was alert. Neurological examination revealed mild dysarthria, expressionless face, diminished blinking, monotonous voice, mild cogwheel rigidity, decreased response to outer stimulations, and dysphagia. The diffusion (Fig. 1-A and B) and fluid-attenuated inversion recovery (Fig. 1-C) images of brain magnetic resonance image (MRI) performed one day after admission showed high-intensity lesions in the bilateral substantia nigra. We also found old infarcts in the right pons and cerebellum on T2-weighted images. Magnetic resonance angiography revealed multiple stenotic lesions in the bilateral internal carotid arteries, left posterior cerebral artery, right anterior inferior cerebellar artery, proximal and distal basilar artery, and left vertebral artery. We supposed that distal basilar artery stenosis was a cause of infarcts in the bilateral substantia nigra. The brain fluorodeoxyglucose positron emission tomography (FDG-PET) performed 8 days after admission revealed a decreased metabolism not only in the midbrain but also in the left frontal cortex (Fig. 1-D and F). A treatment with levodopa/benserazide and methylphenidate was started on day 10. The dose of dopaminergic medication was gradually increased to 200 mg levodopa/ 50 mg benserazide thrice daily. The patient partially recovered about http://dx.doi.org/10.1016/j.jns.2016.12.024 0022-510X/© 2016 Elsevier B.V. All rights reserved. 1 month later. She was able to communicate spontaneously and walk with assistant device. Acute infarcts in the bilateral substantia nigra should be included in the differential diagnosis of akinetic mutism. Some previous studies have reported akinetic mutism with bilateral lesions in the substantia nigra caused by another disease such as encephalitis [5,6]. However, there were no explanations of the pathophysiology about akinetic mutism in these studies. We suggest that the interruption of the frontal-subcortical circuit caused by infarcts in the bilateral substantia nigra led to akinetic mutism in our case. Vascular lesion localized in the bilateral substantia nigra itself is very rare. This could explain the reason there has been no report of akinetic mutism in patients with acute infarcts in the substantia nigra. Acute infarcts in the bilateral substantia nigra on the diffusion image of brain MRI and decreased metabolism in the frontal lobe on FDG PET image in this case may serve an image-based evidence of functional connections from the substantia nigra to the frontal lobe. Conflict of interest None. Disclosures All authors report no disclosures. References [1] L.R. Caplan, J.D. Schmahmann, C.S. Kase, E. Feldmann, G. Baquis, J.P. Greenberg, P.B. Gorelick, C. Helgason, D.B. Hier, Caudate infarcts, Arch. Neurol. 47 (2) (1990) 133–143. [2] M.S. Mega, R.C. Cohenour, Akinetic mutism: disconnection of frontal-subcortical circuits, Neuropsychiatry Neuropsychol. Behav. Neurol. 10 (4) (1997) 254–259. [3] S. Tekin, J.L. Cummings, Frontal-subcortical neuronal circuits and clinical neuropsychiatry: an update, J. Psychosom. Res. 53 (2) (2002) 647–654. [4] N. Nagaratnam, K. Nagaratnam, K. Ng, P. Diu, Akinetic mutism following stroke, J. Clin. Neurosci. 11 (1) (2004) 25–30. [5] S. Y., L.N. Kun, L.S. Haur, H. Tjia, Bilateral substantia nigra changes on MRI in a patient with encephalitis lethargica, Neurology 10 (53) (1999) 1860–1862. [6] H. Verschueren, R. Crols, Bilateral substantia nigra lesions on magnetic resonance imaging in a patient with encephalitis lethargica, J. Neurol. Neurosurg. Psychiatry 71 (2) (2001) 275. Hyun Ah Kim Sooyeoun You⁎ ⁎Corresponding author at: Department of Neurology, Keimyung University School of Medicine, 194 Dongsan dong, Daegu 700-712, South Korea. E-mail address: freeomoi@gmail.com (S. You). 11 October 2016 Available online 18 December 2016 Letter to the Editor 47 Fig. 1. Diffusion -weighted images (A, B) and fluid-attenuated inversion-recovery image (C) of the brain MRI show high signal intensities in the bilateral substantia nigra. Brain fluorodeoxyglucose positron emission tomography reveals decreased glucose metabolism not only in the midbrain (arrow head) (D) but also in the left frontal cortex (arrows) (F).