Acute Cerebellar Ataxia Associated with Anti-glutamic Acid Decarboxylase Antibodies Mimicking Miller Fisher Syndrome

Ataxia and ophthalmoplegia: an atypical case of Miller Fisher syndrome (MFS) with anti-GAD antibody

BACKGROUND

Miller Fisher syndrome (MFS) is frequently encountered variant of Gillian Barre Syndrome (GBS). It has distinct clinical and serological features. Here we describe an atypical GQ1b seronegative case with significantly elevated anti-glutamic acid decarboxylase antibody (GAD-Ab).

CASE DESCRIPTION

A 24-year-old previously healthy Caucasian male presented with rapidly progressive ascending weakness, binocular diplopia and autonomic instability for 2 days. Examination was remarkable for asymmetrical facial weakness (L > R), opthalmoplegia and truncal ataxia without areflexia. MRI brain was normal. CSF analysis showed elevated protein. Electromyography/Nerve Conduction Study (EMG/NCS) within the first week was normal. Antiganglioside antibodies were negative. Extended serological and neoplastic workup revealed negative anti-GQ1b antibody, but significant increase of GAD-Ab, Voltage Gated Calcium Channel (VGCC) Ab, and mild elevation of TPO Ab IgG and Thyroglobulin (Tg) Ab IgG. Clinical diagnosis of partial MFS was made. He received a course of IVIg (2 g/kg over 5 days) and had complete recovery in 3 months.

CONCLUSION

There are incomplete or atypical forms of MFS. Recognition of its various clinical presentations is essential for early diagnosis and optimal management. Further investigation is needed to elucidate the role of anti-GAD-ab and other autoimmune antibodies in the pathogenesis of GQ1b-seronegative MFS patients.

Acute Cerebellar Ataxia Associated with Modest Elevation of Anti-GAD Antibodies in a Young Patient

BACKGROUND

Anti-GAD-related cerebellar ataxia has rarely been described as an acute cause of autoimmune ataxia.

PHENOMENOLOGY SHOWN

A young female who acutely developed anti-GAD-associated ataxia with magnetic resonance imaging (MRI) showing cerebellar edema and follow-up MRI 6 months later showing cerebellar atrophy.

EDUCATIONAL VALUE

Recognizing that anti-GAD-associated cerebellar ataxia can present in a young adult as an acute and severe cause of ataxia, with cerebellar changes evident on MRI.

Immune-mediated Cerebellar Ataxias: Practical Guidelines and Therapeutic Challenges

Immune-mediated cerebellar ataxias (IMCAs), a clinical entity reported for the first time in the 1980s, include gluten ataxia (GA), paraneoplastic cerebellar degenerations (PCDs), antiglutamate decarboxylase 65 (GAD) antibody-associated cerebellar ataxia, post-infectious cerebellitis, and opsoclonus myoclonus syndrome (OMS). These IMCAs share common features with regard to therapeutic approaches. When certain factors trigger immune processes, elimination of the antigen( s) becomes a priority: e.g., gluten-free diet in GA and surgical excision of the primary tumor in PCDs. Furthermore, various immunotherapeutic modalities (e.g., steroids, immunoglobulins, plasmapheresis, immunosuppressants, rituximab) should be considered alone or in combination to prevent the progression of the IMCAs. There is no evidence of significant differences in terms of response and prognosis among the various types of immunotherapies. Treatment introduced at an early stage, when CAs or cerebellar atrophy is mild, is associated with better prognosis. Preservation of the "cerebellar reserve" is necessary for the improvement of CAs and resilience of the cerebellar networks. In this regard, we emphasize the therapeutic principle of "Time is Cerebellum" in IMCAs.