A Rare Case of Global Aphasia Without Hemiparesis (GAWH): An atypical stroke presentation - Presented at ACEM '25, Dubai
Dr Himanshu Gul Mirani, Consultant in Emergency Medicine, MMUH, UK
Case Presentation:
84-year-old male with past medical history of asthma was noted to have a vacant episode by his wife and possibly a minute of abnormal limb shaking. There was no history of incontinence or tongue biting. Prior to this episode, he was well throughout the day. There was no aura, no history of alcohol misuse, no recent head injury, recent infection, or anticoagulant use.
Following this the patient had no word output but no limb weakness. Similar clinical exam was noted by ambulance crew. He was reviewed in the emergency department about one hour since the index symptom onset. He was hemodynamically stable with a regular pulse. He was inattentive to environment with spontaneous eye opening. He was producing incomprehensible sounds. His best motor response was being able to localize pain in all four limbs. There was no facial asymmetry. Babinski response for bilaterally flexor.
Management and Outcome:
Electrocardiogram was sinus rhythm with left axis deviation. Venous blood gas had normal p H and lactate with sodium of 127 mEq/L and blood glucose of 10 mmol/L.
CT scan of the head done in the ED was nil acute for intracranial pathology.
Patient was admitted under stroke service and given loading dose of aspirin (300 mg).
He had an inpatient MRI scan of the brain which showed acute left thalamic stroke. Bilateral carotid doppler showed less than 30% stenosis.
While on the ward the speech function improved, with normal word output and normal speech comprehension. The patient was discharged on clopidogrel.
Key Learning Points:
Global aphasia typically presents with concurrent hemiparesis due to involvement of both Broca's and Wernicke's areas. Global aphasia without hemiparesis (GAWH) represents an unusual stroke syndrome that can present diagnostic challenges in emergency settings.
Recent literature suggests GAWH occurs in approximately 3-6% of all aphasia cases, with cardioembolic sources identified in 60-75% of patients (Nogueira et al., 2023). While previously considered rare, improved neuroimaging has revealed that GAWH may be underdiagnosed due to its atypical presentation mimicking other neurological conditions.
The pathophysiology of GAWH involves strategic lesions affecting language networks while sparing motor pathways. Current research by Hillis and Tippett (2022) demonstrates that thalamic lesions, as in this case, can disrupt cortical language networks through diaschisis effects without compromising motor function. This contrasts with traditional cortical lesion patterns causing combined language and motor deficits.
Emergency clinicians should maintain high suspicion for GAWH in patients presenting with isolated communication deficits, even when initial neuroimaging appears normal, as CT imaging may not detect early or small strategic infarcts. Advanced imaging with MRI diffusion-weighted sequences remains the diagnostic gold standard for these presentations.
Diaschisis refers to a neurological phenomenon where dysfunction occurs in brain areas that are remote from but functionally connected to a primary site of injury. In the context of the case report, the term "diaschisis effects" describes how a thalamic lesion can disrupt language networks despite not directly damaging the classic language centers (Broca's and Wernicke's areas).
Specifically, when the thalamus is damaged, as in this patient's case, it can interrupt the neural connections and pathways that link to cortical language areas. The thalamus serves as an important relay station in the brain, and damage to it can cause functional deactivation or reduced activity in distant but connected cortical regions through various mechanisms:
1. Disruption of thalamocortical circuits that normally facilitate language processing
2. Interruption of neurotransmitter systems that support language function
3. Altered cerebral blood flow or metabolism in connected language areas
This helps explain how the patient could experience global aphasia (suggesting widespread language network dysfunction) despite having only a focal thalamic lesion and without the classic large cortical lesions typically associated with global aphasia. It's an important concept in understanding how relatively small, strategically located lesions can produce surprisingly extensive neurological deficits through their effects on broader brain networks.
The recovery pattern in GAWH varies considerably based on lesion location and extent. Prognosis is generally more favourable than in global aphasia with hemiparesis, with approximately 65% of patients experiencing significant language improvement within three months (Kang et al., 2024).
This case highlights the importance of recognizing atypical stroke presentations in emergency medicine practice and underscores the value of comprehensive neuroimaging in patients with isolated language deficits despite normal motor function.