Neuroacanthocytosis syndromes are a group of various syndromes characterized by progressive degeneration of basal ganglia and red blood cell acanthocytosis. The core neuroacanthocytosis syndromes include chorea-acanthocytosis (ChAc) and X-linked McLeod syndrome (MLS).
ChAc is characterized by choreatic movement, psychiatric symptoms and cognitive decline, and has neuromuscular features including myopathy and axonal neuropathy.
It is known that about 85% patients with ChAc syndromes show elevation of serum CK levels (hyperCKemia). Serum creatine kinase (CK) reflects the integrity of the muscle membrane. It rises in a variety of conditions that cause muscle damage, including the use of myotoxic drugs, endocrine dysfunctions, immune mediated myopathy, and genetic disorders. Therefore, hyperCKemia is a nonspecific marker of muscle damage.
Therefore, when patient is presented with hyperCKemia and other clinical features suspecting ChAc, differentiation from other lesions causing hyperCKemia, especially primary muscle diseases, is required.
We experienced a case of choreo-acanthocytosis misdiagnosed as inflammatory myositis due to lower extremity weakness and hyperCKemia, and treated inappropriately.
A 45-year-old female patient visited the Department of Rehabilitation Medicine at another hospital for dysphagia, mastication difficulty, and bilateral low extremity weakness.
Under the diagnosis of polymyositis, she received oral steroid therapy and IVIG for 3 years, but hyperCKemia and mastication difficulty progressed gradually without improvement. She was referred to our hospital to re-evaluate of the causes of both lower extremities weakness and hyperCKemia refractory to steroid and IVIG treatment.
Considering family history of chorea and oromandibular dystonia, dysphagia, feeding dystonia, lower extremity weakness, hyperCKemia, hyporeflexia, atrophy of bilateral caudate nucleus and T2 hyperintensity in globus pallidus on brain MRI, sensorimotor axonal symmetrical polyneuropathy on EMG, neuroacanthocytosis could be suspected.
Peripheral blood smear (PBS) and gene studies were conducted for confirmatory diagnosis. Acanthocytosis was observed in PBS, and splenomegaly was also observed on spleen sonography. In the genetic test using the next-generation sequencing (NGS) for dystonia, two likely pathogenic variants of the VPS13A gene (NM_033305.2(VPS13A):c.1125_1128delTAAG(;)3943C>T) were discovered. She was finally diagnosed as choreo-acanthocytosis. |
