Hypoglycemic encephalopathy mimicking acute ischemic stroke in clinical presentation and magnetic resonance imaging: a case report

Abstract

Background: The imaging findings of hypoglycemic encephalopathy can be considerably similar to those of ischemic infarction or toxic leukoencephalopathy. We demonstrated unusual magnetic resonance (MR) imaging features of hypoglycemic encephalopathy which can be confused with other pathology both on imaging and acute clinical presentation. The diffusion-weighted imaging (DWI) and apparent diffusion coefficients (ADC) map findings in our case further supports the hypothesis of hypoglycemia-induced "excitotoxic injury" of glial cells and myelin sheath that might protect neuron axons from intracellular edema and irreversible damage.

Case presentation: A 72-year-old woman presented with poor appetite and was initially drowsy at home; the symptoms progressed to loss of consciousness accompanied by mild incontinence. The initial glucose level was 44 mg/dL, but no nausea, vomiting, fever, or cold sweating was reported. Physical examination after intravenous glucose supplementation revealed the absence of focal neurological signs, facial palsy, and tongue or eye deviations. The images obtained 24 h after symptoms onset revealed symmetrical hyperintensities on DWI (b-value: 1000) associated with hypointensities on ADC map along the corticospinal tract, from the levels of the cerebral peduncle and the posterior limbs of the internal capsule to the level of the corona radiata, which may mimic the imaging findings of acute ischemic infarction or amyotrophic lateral sclerosis. The patient received sliding-scale insulin therapy and rehabilitation, and she recovered consciousness without motor function deficits after 1 month. Moreover, repeat DWI and ADC map showed the complete disappearance of the lesions.

Conclusions: In the phenomenon of excitotoxic injury, axons could be protected from intracellular edema and irreversible damage, which may explain the reversible clinical symptoms and imaging abnormality after controlling for blood glucose because of the preserved motor axon. The diagnosis of acute symptomatic hypoglycemic encephalopathy through clinical and imaging features can be challenging. It is crucial to differentiate it from ischemic encephalopathy since the management and clinical outcome are different.

Keywords: Acute ischemic stroke; Diffusion-weighted imaging; Excitotoxic injury; Hypoglycemic encephalopathy.

Fig. 1

Initial axial magnetic resonance imaging conducted at the acute stage of hypoglycemic encephalopathy. Axial diffusion-weighted imaging (a, b, c), apparent diffusion coefficients map (d, e, f), and T2-FLAIR imaging (g, h, i) revealed only water diffusion restriction along the corticospinal tract, from the levels of the cerebral peduncle (a, d, g) and the posterior limbs of the internal capsule (b, e, h) to the level of the corona radiata (c, f, i), which occasionally mimic the imaging findings of acute ischemic stroke

Fig. 2

Repeat axial magnetic resonance imaging conducted 1 month after the patient received sliding-scale insulin therapy and rehabilitation. Axial diffusion-weighted imaging (a, b, c), apparent diffusion coefficients map (d, e, f), and T2-FLAIR imaging (g, h, i) revealed disappearance of the lesions along the corticospinal tract, from the levels of the cerebral peduncle (a, d, g) and the posterior limbs of the internal capsule (b, e, h) to the level of the corona radiata (c, f, i), possibly owing to the preservation of motor axons by the presence of the intramyelinic clefts