Isolated Choreic Manifestations Indicative of Anti-Amphiphysin Antibody-Related Encephalitis in Breast Cancer

Over the past two decades, subacute abnormal movements have been increasingly associated with autoimmune or paraneoplastic encephalitis.¹ Only a few cases, however, have been reported in association with anti-amphiphysin autoantibodies,^2-5 and to our knowledge there is only one reported case of choreic movements in an anti-amphiphysin patient.⁶ Similarly, we report here the case of a woman presenting with brachio-facial choreic movements with anti-amphiphysin autoantibody-related encephalitis in the context of breast cancer. This patient made a remarkable recovery following mastectomy, chemotherapy, and treatment with tetrabenazine.

Anti-amphiphysin antibody-related encephalitis is rare and manifests variable clinical presentations such as stiff person syndrome, sensory ganglionopathy, myelopathy, and cerebellar ataxia.^{3, 5, 7, 8} Our patient did not experience any other common neurological symptoms classically described in anti-amphiphysin antibody-related encephalitis patients such as limbic encephalitis, limb weakness/numbness, ataxia, sleep disorders, or dysautonomia.⁹ On the contrary, she presented isolated choreic movements, which have rarely been described previously in anti-amphiphysin antibody-related encephalitis. Due to the atypical phenomenology and clearly unilateral localization of her abnormal movements, we considered the possibility of a paroxystic etiology prompting us to consider continuous focal epilepsy, as is casually observed in anti-amphiphysin antibody-related encephalitis.² But since no EEG abnormalities and no response to antiepileptic drugs were observed this was ruled out, although the patient's symptoms demonstrably responded to tetrabenazine.

Movement disorders, as a clinical presentation of paraneoplastic neurological syndromes, are rarely seen.¹⁰ However, they may be the prominent and common feature in several autoantibody-associated neurological diseases or paraneoplastic neurological syndromes. Paraneoplastic chorea, in particular, typically starts subacutely, progresses rapidly, and involves the four limbs as well as the trunk, head, and neck. They are very rarely confined to only one hemibody (see Table 1). Moreover, it is an extremely rare occurrence of anti-amphiphysin antibody-related encephalitis.^{11, 12} Thus, this case highlights the importance of considering paraneoplastic origin of an atypical chorea and, notwithstanding the challenges of diagnosing patients with this condition, recognizing and treating the underlying cause is crucial.

(1) Research Project: A. Conception, B. Organization, C. Execution, D. Analysis; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the First Draft, B. Editing of the Final Manuscript.

S.D.: 3A, 3B

M.R.: 1D, 2C

R.B.: 1D, 2C

C.B.: 1C, 2C

M.F.: 1D, 2C

C.L.: 1D, 2C

F.B.: 1C, 2C

J.P.: 1D, 2C

F.O.-M.: 1C, 1D, 3A, 3B

S.D.: None. M.R.: None. R.B.: None. C.B.: None. M.F.: Received honoraria from AbbVie, Orkyn, and BIAL for speaking engagements, and from LVL Médicale for consultancy work; also received grants from the French Ministry of Health and MSA Coalition. C.L.: None. F.B.: None. J.P.: None. F.O.-M.: Served as consultant for AbbVie, Adelia, Homeperf, Bastide, Aguettant, Orkyn, LVL, and Roche; served on advisory boards for AbbVie, Aguettant, LVL, and Roche.