Objective: To describe a case of acute-onset, progressive language impairment resembling PPA developing after RF thalamotomy in a patient with PD.

Background: Primary progressive aphasia (PPA) is rarely reported during the clinical course of idiopathic Parkinson’s disease (IPD). The thalamus has recognized connections with language networks. Language disturbances following thalamotomy are uncommon but may occur depending on lesion location and size.

Method: We report the longitudinal clinical course of a 62-year-old right-handed man with IPD diagnosed in 2012 who underwent left RF thalamotomy in 2021 due to refractory tremor. Postoperative motor, neuropsychological and imaging findings were reviewed over a five-year follow-up.

Results: Immediately after surgery, the patient developed word-finding difficulties, phonemic errors, and social withdrawal despite marked tremor improvement. Over the years, language deficits gradually worsened. By October 2025, neurological examination revealed paraphasia, impaired complex repetition, and speech hesitancy with a MMSE score of 14/30, prominent bradykinesia and mild rigidity in the left upper extremity. Gait remained preserved.

Neuropsychological evaluation suggested a neurodegenerative process dominated by the logopenic variant (lv) of PPA with secondary agrammatic features. Cranial MRI demonstrated a left VIM nucleus lesion consistent with prior thalamotomy and left-sided frontoparietotemporal atrophy. Brain FDG-PET revealed marked hypometabolism in the left posterior and inferior parietal, lateral prefrontal and temporal regions. Plasma pTau217, NfL, and GFAP levels were normal, and the patient declined CSF biomarker analysis. Memantine and speech-language therapy were initiated.

Conclusion: The thalamus plays a key role in dominant-hemisphere language networks, language impairment risk increases with larger lesions. In this tremor-dominant IPD case, acute-onset lvPPA emerged after left thalamotomy. Although lvPPA is often linked to Alzheimer’s pathology, normal plasma pTau217 and levodopa responsiveness make this less likely. The progressive course and widespread cortical hypometabolism are atypical for a purely procedural complication, suggesting that thalamotomy may have unmasked an underlying neurodegenerative process. This case highlights that dominant-hemisphere thalamic lesioning may trigger or reveal progressive aphasic syndromes in IPD, emphasizing the need for careful cognitive follow-up.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/logopenic-aphasia-after-thalamotomy-in-parkinsons-disease-a-case-report/