To describe a rare Nonketotic Hyperglycemic Hyperosmolar State (NKHHS) mimicking a Left Middle Cerebral Artery (MCA) Stroke.

NKHHS is a life-threatening disorder that can rarely present with acute focal neurological deficits imitating a stroke. When present, it commonly mimics posterior circulation stroke. Anterior circulation manifestations are less frequent and, when they occur, usually consist of a partial syndrome, predominantly aphasia, being total hemispheric syndrome extremely rare. The pathophysiology of NKHHS producing acute focal deficits is not fully understood. However, it may be related to hyperosmolarity causing glial dehydration and enhancing metabolic or ischemic disruption of neuronal function. Here, we present a rare NKHHS manifesting as Hemispheric Syndrome mimicking a Left MCA Stroke.

A 62-year-old right-handed female with type-2 diabetes mellitus presented with global aphasia, right-sided hemiplegia, right-sided neglect, and left gaze preference.

Laboratory revealed leukocytosis, hyperglycemia 1016mg/dL, hyperosmolality 328mOsm/kg, and absent urine ketones. CT-Head was normal.  Thrombolytics were contraindicated due to uncertain symptom onset. CT-Brain perfusion demonstrated decreased mean transient time, normal cerebral blood flow, and volume in the left hemisphere. CTA-Head/Neck were unremarkable. MRI-Brain was negative for infarction. Due to concern of non-convulsive status epilepticus, she was started on levetiracetam and continuous electroencephalogram, exhibiting left hemispheric slowing without epileptiform activity. Urinalysis indicated a urinary tract infection. Antibiotics, intravenous fluids, and insulin infusion were initiated. Urine and blood cultures were positive for Streptococcus agalactiae. Due to her lack of improvement in 48-hours, cerebrospinal fluid analysis was pursued. Revealing hyperglycorrhachia 151mg/dL and hyperproteinorrhacia 134.7mg/dL, with negative infectious and autoimmune testing. Once normoglycemia was accomplished, her neurological deficits began to improve, returning to baseline within three days. 

NKHHS mimicking a left MCA stroke is a rare but relevant entity that raises important diagnostic and therapeutic challenges. Recognizing NKHHS as a large vessel stroke mimic allows for better management and prevents unnecessary interventions.