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|LETTERS TO EDITOR
|Year : 2018 | Volume
| Issue : 2 | Page : 534-536
Diffuse cerebellar hypometabolism in 18FDG PET-CT in two long-term followed patients with diagnosis of nonprogressive congenital ataxia
Don-Kyu Kim, Si Hyun Kang, Kyung Mook Seo
Department of Physical Medicine and Rehabilitation, Chung-Ang University College of Medicine, Seoul, South Korea
|Date of Web Publication||15-Mar-2018|
Dr. Si Hyun Kang
Department of Physical Medicine and Rehabilitation, Chung-Ang University Hospital, 224-1 Heuksuk-dong, Dongjak-gu, Seoul
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Kim DK, Kang SH, Seo KM. Diffuse cerebellar hypometabolism in 18FDG PET-CT in two long-term followed patients with diagnosis of nonprogressive congenital ataxia. Neurol India 2018;66:534-6
|How to cite this URL:|
Kim DK, Kang SH, Seo KM. Diffuse cerebellar hypometabolism in 18FDG PET-CT in two long-term followed patients with diagnosis of nonprogressive congenital ataxia. Neurol India [serial online] 2018 [cited 2020 Feb 23];66:534-6. Available from: http://www.neurologyindia.com/text.asp?2018/66/2/534/227314
Nonprogressive congenital ataxia (NPCA) shows characteristic clinical features including hypotonia in infancy and delayed motor development, nonprogressive cerebellar ataxia, intellectual disability, and delayed language development, with the development of dysarthria as the patient ages. The pathophysiology of NPCA is thought to be genetic, and several suspicious gene loci such as ITPR1, CAMTA1, and SCA15 have been investigated; however, no genetic locus has been established to date. NPCA exhibits various degrees of cerebellar hypoplasia in the conventional neuroimaging studies such as computed tomography (CT) and magnetic resonance imaging (MRI), which have limited value because cerebellar hypoplasia is not present in all cases.
Here, we report two cases in which NPCA was suspected and subsequently confirmed by the finding of diffuse cerebellar hypometabolism on (fluorine-18) fluoro-D-glucose (18F-FDG)-positron emission tomography-computed tomography (18FDG PET-CT).
The first case was of a 9-month-old female patient with delayed motor development. The patient's level of gross motor, fine motor, language, and cognitive functions were at the approximate 6-month level [Table 1]. On physical examination, she showed a generalized, severe hypotonia and head titubation in the sitting and prone positions. Moreover, intention tremor was observed in both hands when the patient attempted to hold objects. A brain magnetic resonance imaging (MRI), electrodiagnostic study, and electroencephalogram exhibited no abnormal findings. The results of chromosomal study and microdeletion syndrome screening tests for ataxia were normal. Rehabilitation therapy including physical and occupational therapy was started for her. At subsequent follow-up visits, her gross motor functions had improved but hypotonia and tremor persisted. The patient underwent continuous rehabilitation therapy, and at the age of 18 months, she could walk independently with ataxic features; at this time, her gross motor function was at the approximate 14-month level. However, her language function was markedly delayed as were her fine motor and cognitive functions [Table 1]. She showed an impaired sensory integration and poor eye contact, limited communication, and improper interaction with a caregiver. She was hypersensitive to external stimuli, and did not react properly to changes in position. These clinical features suggested a diagnosis of NPCA, and the patients underwent 18FDG PET-CT, which showed symmetric glucose hypometabolism involving bilateral operculae and decreased FDG uptake in both cerebella [Figure 1]a and [Figure 1]b.
|Figure 1: An 18FDG PET-CT scan at 9-months of age for the female patient (Case 1) showed diffuse cerebellar hypometabolism on both sagittal (a) and coronal (b) views|
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The second case was an 8-month old male child who was referred by a pediatrician to our department because of delayed development. No abnormal findings were observed on brain MRI and brain electroencephalogram. Upon physical examination, he showed a generalized, severe hypotonia and severe head titubation. Deep tendon reflexes were relatively normal and he showed no pathologic reflex. On electrodiagnostic study, there was no definite peripheral neuropathy or myopathy. The results of chromosomal study and microdeletion syndrome screening tests for ataxia were normal. Upon developmental evaluation, which involved the Gross Motor Function Measure (GMFM) and Denver Developmental Screening Test-II (DDST-II), he showed a delayed motor development; his fine motor adaptive level was that of 3–4 months, and the language function was at the approximate 6–7-month level [Table 1]. The patient began rehabilitation therapy, and 1 year later, showed improved but delayed development, and the severe hypotonia persisted. At 3 years of age, he could walk side-to-side while holding on to chairs, although his walking was disturbed by the severe hypotonia and ataxia. He was unable to speak meaningful words and could not properly coordinate with his parents. We recommended 18FDG PET-CT, which showed diffuse hypometabolism in both cerebellar lobes [Figure 2]a and [Figure 2]b. Based on these findings and clinical features, the patient was diagnosed with NPCA.
|Figure 2: An 18FDG PET-CT at 8-months of age for the male patient (Case 2) showed diffuse hypometabolism in the cerebellum on both sagittal (a) and coronal (b) views|
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NPCA is not usually recognizable in early infancy due to its nonspecific symptoms, that is, impaired gross motor function, sensory dysfunction, various degrees of nonprogressive ataxia, and cognitive/language problems at an advanced age. Consequently, confirming a diagnosis of NPCA is problematic, especially in its early stages. Although clinical features of NPCA suggest the cause of the disease to be an abnormal functioning of the regions in which sensory integration and coordination are performed, such as the cerebellum and thalamus, no clear radiographic criteria have been established. The cerebellum has various functions such as integration of sensory input, processing of the information, and transmission of the signals to the cerebral cortex. In addition to these functions, the cerebellum plays an important role in language and cognitive development in early infancy.
The clinical diagnosis in our patients was NPCA; however, there was no cerebellar abnormality detectable on the MRI imaging. Therefore, we performed an 18FDG PET-CT to identify functional impairment in the cerebellum, and both patients showed diffuse hypometabolism in the cerebellum.
The results of the chromosomal study and microdeletion syndrome screening tests for ataxia were normal. We predicted these results because the clinical aspects of our patients did not comply with the other types of hereditary ataxia. They had no family history, showed normal results on electromyography, had no cerebellar atrophy evident on MRI, and had no specific pointer towards a specific type of hereditary ataxia such as telangiectasia. Differential diagnosis of the patients with NPCA would be based on these clinical aspects and not derived from genetic studies because NPCA has a genetic heterogeneity.
The early diagnosis of rare diseases of infants is critical not only for instituting an early therapeutic support but also to enable parents to undertake appropriate measures. Our results suggest that 18FDG PET-CT should be considered for the early detection and confirmation of NPCA in patients in whom cerebellar hypoplasia is not evident on conventional neuroimaging studies.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]