Cognitive dysfunction, social behavior disorder, cerebellar ataxia, and atypical brain FDG-PET presentation in spinocerebellar ataxia 17: a case report.

BACKGROUND: Spinocerebellar ataxia 17 (SCA17) is a rare autosomal dominant form of inherited ataxia, caused by heterozygous trinucleotide repeat expansions encoding glutamine in the TATA box-binding protein (TBP) gene. CASE DESCRIPTION: We describe the clinical history, neuropsychological, and neuroimaging findings of a 42-year-old patient who presented for medical attention showing prevalent behavioral and cognitive problems along with progressively worsening gait disturbances. The patient's family history indicated the presence of SCA17 in the maternal lineage. Genetic analysis confirmed a heterozygous 52-CAG pathological expansion repeat in TBP (normal interval, 25-40 CAG. Brain 18-fluorodeoxyglucose positron emission tomography (FDG-PET) showed bilateral hypometabolism in the sensorimotor cortex, with a slight predominance on the right, as well as in the striatal nuclei and thalamic hypermetabolism, a finding similar to what is observed in Huntington's disease. The patient also underwent neuropsychological evaluation, which revealed mild cognitive impairment and difficulties in social interaction and understanding other's emotions (Faux Pas Test and Reading the Mind in the Eyes Test). CONCLUSION: Our report emphasizes the importance of considering SCA17 as a possible diagnosis in patients with a prevalent progressive cognitive and behavioral disorders, even with a pattern of FDG-PET hypometabolism not primarily indicative of this disease.

[A case of Holmes tremor in which 123I-IMP SPECT and MRI findings suggest damage to the cerebellothalamic tract and the dentato-rubro-olivary pathway].

A 75-year-old woman was referred to our department in October 2022 with ataxia and involuntary movements of the right upper and lower limbs. She had experienced a left pontine hemorrhage in March 2021, which was managed conservatively. However, she had residual right-sided hemiplegia. In addition, she had cerebellar ataxia and a 2 |Hz resting tremor of the right upper and lower limbs, which was enhanced while maintaining posture and contemplation. Based on her history, and the findings of MRI and nuclear medicine imaging, we diagnosed the patient with Holmes tremor due to pontine hemorrhage. Holmes tremor is a rare movement disorder secondary to brainstem and thalamic lesions, characterized by a unilateral low-frequency tremor. In this case, 123I-IMP SPECT and MRI shows damage to the cerebellothalamic tract and dentaro-rubro-olivary pathway.

Cerebellar Ataxia With Neuropathy and Vestibular Areflexia Syndrome Due to Replication Factor C Subunit 1 Gene Repeat Expansion.

ABSTRACT: A 56-year-old man was born to consanguineous parents. He experienced slow-progressing sensory disturbances in the upper extremities. T1-weighted images showed cerebellar atrophy. 123I-IMP SPECT revealed reduced cerebral blood flow in the cerebellum. 123I-FP-CIT SPECT showed low uptake of dopamine transporter in the bilateral tail of the striatum. 123I-MIBG scintigraphy shows a decreased heart-to-mediastinum ratio. Flanking polymerase chain reaction suggested biallelic repeat expansion in intron 2 of RFC1, and subsequent repeat-primed polymerase chain reaction revealed ACAGG repeat expansion. Thus, he was diagnosed as cerebellar ataxia with neuropathy and vestibular areflexia syndrome.

Autoimmune Cerebellar Ataxia Associated with Anti-Glutamate Receptor δ2 Antibodies: a Rare but Treatable Entity.

We report two novel cases of autoimmune cerebellar ataxia (ACA) associated with anti-glutamate receptor δ2 antibodies (Gluδ2-Abs). The first case was confirmed by indirect immunofluorescence and cell-based assays: a 29-year-old woman presented after 5 days of headache and vomiting, a pancerebellar syndrome, downbeat nystagmus, decreased visual acuity linked to bilateral retrobulbar optic neuritis (RON), and lymphocytic pleocytosis in the cerebrospinal fluid (CSF) without any abnormality detected using cerebral magnetic resonance imaging (MRI). Second-line immunotherapy allowed progressive clinical improvement, with full recovery achieved after a 4-year follow-up. Thereafter, we retrospectively tested Gluδ2-Abs in 350 patients with a suspicion of autoimmune encephalitis without characterized autoantibody. We identified a second case, a 12-year-old boy who developed 10 days after a respiratory infection, a static cerebellar syndrome with lymphocytosis in the CSF, and right cerebellum hyperintensity in MRI. Five days of corticosteroid treatment allowed a quick clinical improvement. No tumor was identified in both cases, whereas laboratory analyses revealed autoimmune stigma. The present cases suggested that ACA associated with Gluδ2-Abs is an extremely rare but treatable disease. Therefore, testing for Gluδ2-Abs might be considered in the setting of suspected ACA and no initial antibody identification. The visual deficits and ocular motility abnormalities observed in the first reported case might be part of the clinical spectrum of Gluδ2-Abs ACA. Young age, infectious prodromes, lymphocytic pleocytosis, and autoimmune background usually appear together with this syndrome and should lead to discuss the initiation of immunotherapy (after ruling out differential diagnosis, especially infectious causes).

A Review of Brain and Pituitary Gland MRI Findings in Patients with Ataxia and Hypogonadism.

The association of cerebellar ataxia and hypogonadism occurs in a heterogeneous group of disorders, caused by different genetic mutations often associated with a recessive inheritance. In these patients, magnetic resonance imaging (MRI) plays a pivotal role in the diagnostic workflow, with a variable involvement of the cerebellar cortex, alone or in combination with other brain structures. Neuroimaging involvement of the pituitary gland is also variable. Here, we provide an overview of the main clinical and conventional brain and pituitary gland MRI imaging findings of the most common genetic mutations associated with the clinical phenotype of ataxia and hypogonadism, with the aim of helping neuroradiologists in the identification of these disorders.

Widening the clinical, radiological and genetic spectrum of autosomal recessive ataxia of Charlevoix-Saguenay in Indian patients.

BACKGROUND: Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS), classically presenting as a triad of early-onset cerebellar ataxia, lower extremity spasticity and peripheral neuropathy, is caused by mutations in SACS gene which encodes the protein sacsin. OBJECTIVE: To provide new insight into the occurrence of SACS mutations in South India. METHODS: Patients with three cardinal features of ARSACS-peripheral neuropathy, cerebellar ataxia, and pyramidal tract signs were included. Nine patients were clinically identified and genetically evaluated. Mutation screening of SACS by targeted sequencing of 40 recessive ataxia genes panel by next-generation sequencing was conducted. Additional investigations included magnetic resonance imaging (MRI), fundoscopy, optical coherence tomography (OCT) and nerve conduction studies (NCS). Functional disability was assessed by the Spinocerebellar Degeneration Functional Score. RESULTS: Two hundred and fifteen cerebellar ataxia patients were screened, and 9 patients with cerebellar ataxia with spasticity, peripheral neuropathy and MRI brain characteristics, consistent with a clinical diagnosis of ARSACS were identified, of which 7 patients were identified to have mutation in the SACS gene and are detailed hereafter. Age of presentation ranged from 20 to 55 years (29.8 ± 11.9) with a mean disease duration of 12.7 years (SD-7.65, range 5-22 years). All except one had onset of symptoms in the form of an ataxic gait noticed before 20 years of age. Additional features were subnormal intelligence (4/7), slow and hypometric saccades (1/7), seizures (1/7), kyphoscoliosis (1/7) and dysmorphic facies (1/7). SDFS was 3 in 5/7 patients signifying moderate disability with independent ambulation. MRI showed cerebellar atrophy with predominant atrophy of the superior vermis (7/7), horizontal linear T2 hypointensities in the pons(7/7), hyperintensities where lateral pons merges with the middle cerebellar peduncle (MCP) (7/7) well seen in fluid-attenuated inversion recovery (FLAIR) images, thickening of MCP (3/7), symmetric lateral thalamic hyperintensities (6/7), posterior fossa arachnoid cyst (4/7),thinning of posterior mid-body of corpus callosum (7/7), marginal mineralisation of the basal ganglia (7/7), bilateral parietal atrophy (7/7) and thinning of corticospinal tract on diffusion tensor imaging (DTI) (7/7). We identified pathogenic homozygous frameshift mutations in the SACS gene in six patients (including two siblings), while one patient had a heterozygous pathogenic deletion. CONCLUSIONS: This is the largest series of genetically confirmed ARSACS patients from India highlighting the clinical, ophthalmological, imaging and genetic features of this cohort.

Novel homozygous frameshift variant in the ATCAY gene in an Iranian patient with Cayman cerebellar ataxia; expanding the neuroimaging and clinical features: a case report.

BACKGROUND: Pathogenic variants in the ATCAY gene are associated with a rare autosomal recessive disorder called Cayman cerebellar ataxia. Affected individuals display psychomotor retardation, cerebellar dysfunction, nystagmus, intention tremor, ataxic gait and dysarthric in some cases. CASE PRESENTATION: Whole exome sequencing was performed for a 21-month-old girl suffering from developmental delay specifically in motor and language aspects, hypotonia, nystagmus, pes planus and strabismus. The detected variant in the patient was confirmed by family segregation analysis by Sanger sequencing in both of her parents. Previously three homozygous variants in the ATCAY gene (missense, splice site and frameshift deletion) have been reported in patients with Cayman cerebellar ataxia. Here we report the fourth homozygous variant and the second homozygous frameshift deletion in this gene to be associated with autosomal recessive Cayman cerebellar ataxia. CONCLUSION: The identification of this novel homozygous frameshift deletion in the ATCAY gene expands our understanding of the genetic landscape underlying Cayman cerebellar ataxia. Furthermore, the occurrence of this variant in Iran, in addition to Pakistan, signifies the importance of considering genotypic and phenotypic factors beyond ethnicity when studying this disorder. These findings contribute to the ongoing efforts to unravel the molecular basis of Cayman cerebellar ataxia and improve diagnostic approaches and potential therapeutic interventions.

Pure cerebellar ataxia due to bi-allelic PRDX3 variants including recurring p.Asp202Asn.

Bi-allelic variants in peroxiredoxin 3 (PRDX3) have only recently been associated with autosomal recessive spinocerebellar ataxia characterized by early onset slowly progressive cerebellar ataxia, variably associated with hyperkinetic and hypokinetic features, accompanied by cerebellar atrophy and occasional olivary and brainstem involvement. Herein, we describe a further simplex case carrying a reported PRDX3 variant as well as two additional cases with novel variants. We report the first Brazilian patient with SCAR32, replicating the pathogenic status of a known variant. All presented cases from the Brazilian and Indian populations expand the phenotypic spectrum of the disease by displaying prominent neuroradiological findings. SCAR32, although rare, should be included in the differential diagnosis of sporadic or recessive childhood and adolescent-onset pure and complex cerebellar ataxia.

Disability in cerebellar ataxia syndromes is linked to cortical degeneration.

OBJECTIVE: We aimed to relate clinical measures of disability in chronic cerebellar degeneration to structural whole-brain changes using voxel-based and surface-based morphometry (vbm and sbm). We were particularly interested in remote effects of cerebellar degeneration in the cerebral cortex. METHODS: We recruited 30 patients with cerebellar degeneration of different aetiologies (downbeat nystagmus syndrome, DBN n = 14, spinocerebellar ataxia, SCA n = 9, sporadic adult late-onset ataxia, SAOA n = 7). All patients were thoroughly characterised in the motor, cognitive, vestibular and ocular-motor domains. Vbm and sbm were used to evaluate structural differences between cerebellar degeneration patients and a group of healthy age- and gender-matched volunteers. Linear regression models were used to correlate functional measures of disease progression and postural stability with whole brain volumetry. RESULTS: Patients with SCA and SAOA showed widespread volume loss in the cerebellar hemispheres and less prominently in the vermis. Patients with DBN showed a distinct pattern of grey matter volume (GMV) loss that was restricted to the vestibular and ocular-motor representations in lobules IX, X and V-VII. Falls were associated with brainstem white matter volume. VBM and SBM linear regression models revealed associations between severity of ataxic symptoms, cognitive performance and preferred gait velocity. This included extra-cerebellar (sub-)cortical hubs of the motor and locomotion network (putamen, caudate, thalamus, primary motor cortex, prefrontal cortex) and multisensory areas involved in spatial navigation and cognition. CONCLUSION: Functional disability in multiple domains was associated with structural changes in the cerebral cortex.

Assessment of anti-GAD65-associated cerebellar ataxia with 18F-FDG cerebellar uptake: ROC analysis.

OBJECTIVE: Anti-glutamic acid decarboxylase 65 (anti-GAD65)-associated neurological disorders include two major phenotypes, namely Stiff person syndrome (SPS) and cerebellar ataxia (CA). Considering the potential for better outcomes with prompt immunotherapy, early detection of CA is crucial. Hence, a non-invasive imaging biomarker to detect CA with high specificity is desired. Herein, we evaluated brain 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG) PET in detecting CA based on cerebellar uptake using receiver operating characteristic (ROC) analysis and five-fold cross-validation. METHODS: This study was based on STARD 2015 guidelines: thirty patients with anti-GAD65-associated neurological disorders, 11 of whom with CA were studied. Five test sets were created after patients were randomly sorted and divided into 5 equal folds. Each iteration included 24 patients for ROC analysis and 6 patients reserved for testing. The Z scores of left cerebellum, vermis, right cerebellum, and the average of the three regions were used in ROC analysis to determine areas with significant area under the curve (AUC). The cut-off values with high specificity were determined among the 24 patients in each iteration and tested against the reserved 6 patients. RESULTS: Left cerebellum and average of the three regions showed significant AUC above 0.5 in all iterations with left cerebellum being the highest AUC in 4 iterations. Testing the cut-off values of the left cerebellum against the reserved 6 patients in each iteration showed 100% specificity with sensitivities ranging from 0 to 75%. CONCLUSIONS: Cerebellar 18F-FDG PET uptake can differentiate CA phenotypes from patients with SPS with high specificity.

Hypomagnesemia, a Rare Cause of Reversible Ataxia.

Background: A 61-year-old male patient presented with cerebellar syndrome, which had progressively worsened for 10 days, followed by a tonic-clonic seizure. Phenomenology Shown: Blood analysis showed severe hypomagnesemia and a brain MRI showed T2 hyperintensity in the cerebellar hemispheres (Figure 1). Therefore, the final diagnosis was cerebellar syndrome and epileptic seizures secondary to severe hypomagnesemia. Educational Value: In cases of subacute onset of ataxia, the possibility of ataxia secondary to hypomagnesemia should be considered, as it can be diagnosed with a basic blood test and there are potentially life-threatening outcomes in the absence of treatment, with a reversible course following early supplementation.

[Episodic ataxia type 2: a clinical, genetic and radiological study of 10 patients]. / Ataxia episódica tipo 2: estudio clínico, genético y radiológico de 10 pacientes.

OBJECTIVES: To describe a series of patients with episodic ataxia type 2 (EA2), attending to epidemiological, clinical, radiological, and therapeutic variables. MATERIAL AND METHODS: Retrospective revision of patients with molecular diagnosis of EA2 (CACNA1A mutations), between 1988 and 2022. Information achieved from the database of our Movement Disorders clinic. A descriptive statistical analysis was made. RESULTS: Ten patients from five families were analyzed (six women). Median age at diagnosis was 37.5 years-old, with a median diagnostic delay of 20 years. 70% reported familial history of CACNA1A associated symptoms, although 50% presented migraine, epilepsy, dystonia, or neuropsychiatric alterations. Two heterozygous consanguineous patients had homozygotic descendance with infant mortality due to early-onset epileptic encephalopathy type 42. Five pathogenic/probably pathogenic CACNA1A variants were detected. 80% of patients had episodic triggers, being stress the most common. Episodes had a weekly frequency before treatment initiation. Six patients developed chronic ataxia (one patient demand gait support). 50% of patients with neuroimaging presented cerebellar atrophy. Acetazolamide were initiated in 80%, and 75% of them showed improvement of episodic symptoms. Nephrolithiasis was the most frequent side effect. CONCLUSIONS: EA2 has a great intrafamilial and interfamilial phenotypic variability. The most frequent phenotype were weekly episodes of unsteadiness, several hours of length, stress as the main trigger, chronic ataxia and gaze-evoked nystagmus. Acetazolamide is effective, although complications are usual. Neurologist must be alert as diagnostic delay is constant.

TITLE: Ataxia episódica tipo 2: estudio clínico, genético y radiológico de 10 pacientes.Objetivo. Describir una serie de pacientes con ataxia episódica tipo 2 (AE2) según variables epidemiológicas, clínicas, radiológicas y terapéuticas. Material y métodos. Revisión retrospectiva de pacientes con diagnóstico molecular de AE2 (mutación en CACNA1A) entre 1988 y 2022, información recogida de la base de datos de la Unidad de Trastornos del Movimiento de nuestro centro. Se realizó un análisis estadístico descriptivo. Resultados. Se analizó a 10 pacientes procedentes de cinco familias. La mediana de edad en el momento del diagnóstico fue 37,5 años, con un retraso diagnóstico de 20 años. El 50% asociaba epilepsia, migraña, distonía o alteraciones neuropsiquiátricas. El 70% tenía una historia familiar de síntomas asociados a CACNA1A. Dos pacientes heterocigotos consanguíneos tuvieron descendencia homocigota con mortalidad infantil por encefalopatía epiléptica de inicio precoz de tipo 42. Se detectaron cinco variantes diferentes de CACNA1A. El 80% mostró factores desencadenantes, y el estrés fue el más común. La frecuencia episódica más habitual fue semanal. Seis pacientes desarrollaron ataxia interepisódica, aunque sólo uno precisó apoyo en la marcha. El 50% de los pacientes con neuroimagen presentó atrofia cerebelosa. El 80% inició acetazolamida durante el seguimiento, con respuesta a dosis altas en el 75%. La nefrolitiasis fue el efecto adverso más frecuente. La 4-aminopiridina fue una alternativa eficaz. Conclusiones. La AE2 presenta una alta variabilidad fenotípica inter- e intrafamiliar. El fenotipo más frecuente fueron episodios de inestabilidad, de horas de duración, semanales, con estrés como desencadenante, ataxia persistente y nistagmo evocado por la mirada. La acetazolamida, aunque es eficaz, no está exenta de complicaciones. El retraso diagnóstico es muy frecuente.

Slowly Progressive Cerebellar Ataxia in a 55-Year-Old Female Patient.

A 55-year-old female patient with a history of hypercholesterolemia and anxiety presented for imbalance, fear of falling, and progressive disability. Examination revealed gaze-evoked horizontal nystagmus, ataxic dysarthria, sensory neuronopathy, and cerebellar atrophy. What is your diagnosis?

Ultrasound of peripheral nerves distinguishes inherited sensory neuronopathy of cerebellar ataxia with neuropathy and vestibular areflexia syndrome from inherited axonopathy.

Introduction/Aims Recent studies have shown that ultrasound of peripheral nerves can distinguish inherited sensory neuronopathy from acquired axonopathy with a high degree of accuracy. In this study we aimed to determine whether ultrasound can also distinguish inherited sensory neuronopathy from inherited axonopathy. Methods We compared the ultrasound cross-sectional areas (CSAs) of the median, ulnar, sural, and tibial nerves of retrospectively recruited patients with cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS), in whom sensory neuronopathy is a cardinal feature, with Charcot-Marie-Tooth type 2 (CMT2) disease patients, who have an inherited axonopathy, using the Kruskal-Wallis test and receiver-operating characteristic curves. Results There were 17 patients with CANVAS and 18 with CMT2. The upper limb nerve CSAs were significantly smaller in CANVAS than in CMT2 (P < .001), with the CSAs of the median nerve at mid-forearm and ulnar nerve at mid-arm being a third or less the size of those of the CMT2 patients. Nerve ultrasound reliably distinguished CANVAS from CMT2 with ROC areas under the curve between 0.97 and 0.99. The lower limb CSAs of the two patient groups were not significantly different. Discussion Ultrasound of the upper limb nerves distinguishes CANVAS sensory neuronopathy from inherited axonopathy with high accuracy and can therefore be proposed as a reliable additional tool in the investigation of these diseases.

Acetyl-DL-leucine in cerebellar ataxia ([18F]-FDG-PET study): how does a cerebellar disorder influence cortical sensorimotor networks?

OBJECTIVE: The aim of the study was to deepen our insights into central compensatory processes of brain networks in patients with cerebellar ataxia (CA) before and with treatment with acetyl-DL-leucine (AL) by means of resting-state [18F]-FDG-PET brain imaging. METHODS: Retrospective analyses of [18F]-FDG-PET data in 22 patients with CA (with vestibular and ocular motor disturbances) of different etiologies who were scanned before (PET A) and on AL treatment (PET B). Group subtraction analyses, e.g., for responders and non-responders, comparisons with healthy controls and correlation analyses of regional cerebral glucose metabolism (rCGM) with symptom duration, ataxia (SARA) and quality of life (QoL) scores were calculated. RESULTS: Prior to treatment rCGM was consistently downregulated at the cerebellar level and increased in multisensory cortical areas, e.g., somatosensory, primary and secondary visual (including V5, precuneus), secondary vestibular (temporal gyrus, anterior insula), and premotor/supplementary motor areas. With AL (PET B vs. A) cerebellar hypometabolism was deepened and sensorimotor hypermetabolism increased only in responders with clinical benefit, but not for the non-responders and the whole CA group. A positive correlation of ataxia improvement with rCGM was found in visual and vestibular cortices, a negative correlation in cerebellar and brainstem areas. QoL showed a positive correlation with rCGM in the cerebellum and symptom duration in premotor and somatosensory areas. CONCLUSIONS: Central compensatory processes in CA mainly involve multisensory visual, vestibular, and somatosensory networks as well as premotor/primary motor areas at the cortical level. The enhanced divergence of cortical sensorimotor up- and cerebellar downregulation with AL in responders could reflect amplification of inhibitory cerebellar mechanisms.

Clinical Features and Neuroimaging Findings of Neuropil Antibody-Positive Idiopathic Sporadic Ataxia of Unknown Etiology.

Idiopathic sporadic ataxia (ISA) is the clinical term for nonfamilial ataxia with adult-onset and a slowly progressive course. However, immune-mediated cerebellar ataxia cannot be completely excluded from ISA. The current study investigated the neuropil antibodies against cell-surface antigens and clarified the clinical features and neuroimaging findings of patients with these antibodies. Using tissue-based immunofluorescence assays (TBAs), we examined antibodies against the cerebellum in serum samples from 67 patients who met the ISA diagnostic criteria, including 30 patients with multiple system atrophy with predominant cerebellar features (MSA-C) and 20 patients with hereditary ataxia (HA), and 18 healthy control subjects. According to the TBA results, we divided subjects into three groups: subjects positive for neuropil antibodies, subjects positive for intracellular antibodies only, and subjects negative for antibodies. We compared clinical features and neuroimaging findings in ISA patients among these three groups. The prevalence of neuropil antibodies in ISA (17.9%) was significantly higher than that in MSA-C (3.3%), HA (0%), or healthy subjects (0%). The neuropil antibody-positive ISA patients showed pure cerebellar ataxia more frequently than the other ISA patients. Two neuropil antibody-positive patients showed significant improvement of cerebellar ataxia after immunotherapy. We detected neuropil antibodies in 17.9% of ISA patients. Characteristic clinical features of neuropil antibody-positive ISA patients were pure cerebellar ataxia. Some cases of neuropil antibody-positive ISA responded to immunotherapy.

Multiple system atrophy with anti-NAE antibody refractory to immunotherapy: A case report.

A 51-year-old Japanese man presented with slowly progressing cerebellar ataxia from age 49. Anti-thyroglobulin, anti-thyroid peroxidase, and anti-NAE antibodies were detected. Brain magnetic resonance imaging showed moderate atrophy of the pons, cerebellum, and middle cerebellar peduncle. Dopamine transporter single-photon emission computed tomography showed normal uptake. With the diagnosis of Hashimoto's encephalopathy, repeated steroid pulse therapy and intravenous immunoglobulin therapy were administered; however, they were ineffective for cerebellar ataxia. Afterwards, autonomic failure and parkinsonism became evident. The final diagnosis was MSA of the cerebellar type. Immunotherapies for patients with MSA with anti-NAE antibodies should be carefully considered.

The cerebellar bioenergetic state predicts treatment response in COQ8A-related ataxia.

INTRODUCTION: Primary coenzyme Q10 (CoQ10) deficiency, a recessive disorder associated with various defects of CoQ10 biosynthesis and widely varying clinical presentation, is customarily managed by oral Q10 supplementation but the benefit is debated. METHODS: To address this question, we mapped individual responses in two patients with COQ8A-related ataxia following coenzyme Q10 supplementation using noninvasive imaging. Metabolic 31phosphorus magnetic resonance spectroscopy imaging (31P-MRSI) and volumetric cerebellar neuroimaging were performed to quantify the individual treatment response in two patients with COQ8A-related ataxia, each compared with eight age- and gender-matched healthy control subjects. RESULTS: Post-treatment change in energy metabolite levels differed in the two patients, with higher energy levels and improved dysarthria and leg coordination in one, and decreased energy levels without clinical benefit in the other. CONCLUSIONS: Our results suggest that the cerebellar bioenergetic state may predict treatment response in COQ8A-related ataxia and highlight the potential of pathophysiology-orientated neuroimaging evidence to inform treatment decisions.