A systematic scoping review of the literacy skills of children with childhood apraxia of speech: Recommendations for best practice and further research.

PURPOSE: Little is known about the literacy skills of children with childhood apraxia of speech (CAS) or effective methods for teaching them to read. This systematic scoping review aimed to synthesise what is known about this issue. METHOD: Nine databases were searched to identify relevant articles. Included articles were categorised by study design, quality, and confidence of CAS diagnosis. RESULT: Twenty-three articles were included, 17 described literacy skills of children with CAS and six trialled literacy interventions. Children with CAS had early skills deficits that manifest as literacy difficulties in the later school years and beyond. They frequently had poorer outcomes compared with both typical readers and children with other speech disorders. Both the extent of literacy impairment and responsiveness to intervention appear to be related to the severity of speech impairment. Four literacy interventions for children with CAS were identified. CONCLUSIONS: Children with CAS are at high risk of literacy difficulty and may require early literacy intervention to help them attain academic success. Further research is warranted to determine the longer-term literacy outcomes of children with CAS, appropriate means of assessment, and whether a systematic synthetic phonics approach is an effective form of literacy instruction for this population.

Childhood Apraxia of Speech: A Descriptive and Prescriptive Model of Assessment and Diagnosis.

Childhood apraxia of speech (CAS) represents a significant diagnostic and therapeutic challenge within the field of clinical neuropsychology, characterized by its nuanced presentation and multifactorial nature. The aim of this study was to distil and synthesize the broad spectrum of research into a coherent model for the assessment and diagnosis of CAS. Through a mixed-method design, the quantitative phase analyzed 290 studies, unveiling 10 clusters: developmental apraxia, tabby talk, intellectual disabilities, underlying speech processes, breakpoint localization, speech characteristics, functional characteristics, clinical practice, and treatment outcome. The qualitative phase conducted a thematic analysis on the most cited and recent literature, identifying 10 categories: neurobiological markers, speech motor control, perceptual speech features, auditory processing, prosody and stress patterns, parent- and self-report measures, intervention response, motor learning and generalization, comorbidity analysis, and cultural and linguistic considerations. Integrating these findings, a descriptive and prescriptive model was developed, encapsulating the complexities of CAS and providing a structured approach for clinicians. This model advances the understanding of CAS and supports the development of targeted interventions. This study concludes with a call for evidence-based personalized treatment plans that account for the diverse neurobiological and cultural backgrounds of children with CAS. Its implications for practice include the integration of cutting-edge assessment tools that embrace the heterogeneity of CAS presentations, ensuring that interventions are as unique as the children they aim to support.

Augmentative and alternative communication in autism spectrum disorder: transitioning from letter board to iPad - a case study.

This case study examines the effective use of Augmentative and Alternative Communication (AAC) tools in enhancing communication skills in a 15-year-old male with Autism Spectrum Disorder (ASD). Initially exhibiting non-verbal tendencies, the subject experienced significant improvements in communication and social interaction following the introduction of a letter board and subsequent transition to an iPad. These AAC tools facilitated a marked development in his ability to articulate thoughts, engage in academic activities, and express complex ideas, particularly in science. The study highlights the role of AAC in expanding the communicative capabilities of individuals with limited or no verbal language, demonstrating notable advancements in both verbal expression and cognitive engagement. The findings underscore the transformative impact of personalized AAC interventions and suggest the potential for broader application in ASD support strategies. This case highlights the need for further research, including randomized controlled trials, to explore the efficacy of AAC tools in diverse ASD contexts.

Pick's Disease Presenting as Tremulous Parkinsonism with Limited Levodopa Response-A Rare Cause of Corticobasal Syndrome.

BACKGROUND: Corticobasal syndrome is a clinical diagnosis and common pathological causes are corticobasal degeneration, progressive supranuclear palsy and Alzheimer's disease. OBJECTIVES: We would like to highlight a rare but important differential of corticobasal syndrome. METHODS: A 78-year-old female had a 4-year history of predominantly right-hand rest tremor, worsening of handwriting but no change in cognition. The clinical examination showed right upper limb postural and kinetic tremor, mild wrist rigidity and reduced amplitude of right-sided finger tapping. She was initially diagnosed as idiopathic Parkinson's disease. Five years after onset of symptoms, she demonstrated bilateral myoclonic jerks and right upper limb dystonic posturing. She could not copy movements with the right hand. The magnetic resonance imaging (MRI) revealed disproportionate atrophy in the parietal lobes bilaterally. The clinical diagnosis was changed to probable corticobasal syndrome. She passed away 11 years from onset of symptoms at the age of 85 years. She underwent a post-mortem. RESULTS: The anterior and posterior frontal cortex, anterior cingulate, temporal neocortex, hippocampus and amygdaloid complex demonstrated considerable tau-related pathology consisting of a dense background of neuropil threads, and rounded, paranuclear neuronal inclusions consistent with Pick bodies. The immunostaining for three microtubule binding domain repeats (3R) tau performed on sections from the frontal and temporal lobes, basal ganglia and midbrain highlighted several inclusions whilst no 4R tau was observed. She was finally diagnosed with Pick's disease. CONCLUSIONS: Pick's disease can rarely present with clinical features of corticobasal syndrome.

The yes-no reversal phenomenon in patients with primary progressive apraxia of speech.

Patients who have a yes-no reversal respond "yes" when they mean no and vice versa. The unintentional response can be made both verbally and with gestures (e.g., head shake or nod, thumbs up or down). Preliminary reports associate this phenomenon with 4-repeat tauopathies including primary progressive apraxia of speech (PPAOS), nonfluent/agrammatic primary progressive aphasia, and corticobasal syndrome; however, the significance and timing of this symptom relative to others are not well understood. Whereas some accounts associate yes-no reversals with other binary reversals (e.g., up/down, hot/cold) and attribute the reversals to disturbances of selection within the language system, others implicate more general inhibitory control processes. Here, we compared clinical and neuroimaging findings across 30 patients with PPAOS (apraxia of speech in the absence of aphasia), 15 of whom had a yes-no reversal complaint and 15 who did not. The two groups did not differ on any of the language or motor speech measures; however, patients who had the yes-no reversal received lower scores on the Frontal Assessment Battery and motor assessments. They also had greater hypometabolism in the left supplementary motor area and bilateral caudate nuclei on [18F]-fluorodeoxyglucose PET, but only the right caudate nucleus cluster survived correction for multiple comparisons. We interpret these results to suggest that the yes-no reversal phenomenon is associated with cognitive abilities that are supported by the frontostriatal network; more specifically, impaired response inhibition.

Multimodal cross-examination of progressive apraxia of speech by diffusion tensor imaging-based tractography and Tau-PET scans.

Progressive apraxia of speech (PAOS) is a 4R tauopathy characterized by difficulties with motor speech planning. Neurodegeneration in PAOS targets the premotor cortex, particularly the supplementary motor area (SMA), with degeneration of white matter (WM) tracts connecting premotor and motor cortices and Broca's area observed on diffusion tensor imaging (DTI). We aimed to assess flortaucipir uptake across speech-language-related WM tracts identified using DTI tractography in PAOS. Twenty-two patients with PAOS and 26 matched healthy controls were recruited by the Neurodegenerative Research Group (NRG) and underwent MRI and flortaucipir-PET. The patient population included patients with primary progressive apraxia of speech (PPAOS) and non-fluent variant/agrammatic primary progressive aphasia (agPPA). Flortaucipir PET scans and DTI were coregistered using rigid registration with a mutual information cost function in subject space. Alignments between DTI and flortaucipir PET were inspected in all cases. Whole-brain tractography was calculated using deterministic algorithms by a tractography reconstruction tool (DSI-studio) and specific tracts were identified using an automatic fiber tracking atlas-based method. Fractional anisotropy (FA) and flortaucipir standardized uptake value ratios (SUVRs) were averaged across the frontal aslant tract, arcuate fasciculi, inferior frontal-occipital fasciculus, inferior and middle longitudinal fasciculi, as well as the SMA commissural fibers. Reduced FA (p < .0001) and elevated flortaucipir SUVR (p = .0012) were observed in PAOS cases compared to controls across all combined WM tracts. For flortaucipir SUVR, the greatest differentiation of PAOS from controls was achieved with the SMA commissural fibers (area under the receiver operator characteristic curve [AUROC] = 0.83), followed by the left arcuate fasciculus (AUROC = 0.75) and left frontal aslant tract (AUROC = 0.71). Our findings demonstrate that flortaucipir uptake is increased across WM tracts related to speech/language difficulties in PAOS.

A targeted review of prosodic production in agrammatic aphasia.

It is unclear whether individuals with agrammatic aphasia have particularly disrupted prosody, or in fact have relatively preserved prosody they can use in a compensatory way. A targeted literature review was undertaken to examine the evidence regarding the capacity of speakers with agrammatic aphasia to produce prosody. The aim was to answer the question, how much prosody can a speaker "do" with limited syntax? The literature was systematically searched for articles examining the production of grammatical prosody in people with agrammatism, and yielded 16 studies that were ultimately included in this review. Participant inclusion criteria, spoken language tasks, and analysis procedures vary widely across studies. The evidence indicates that timing aspects of prosody are disrupted in people with agrammatic aphasia, while the use of pitch and amplitude cues is more likely to be preserved in this population. Some, but not all, of these timing differences may be attributable to motor speech programming deficits (AOS) rather than aphasia, as these conditions frequently co-occur. Many of the included studies do not address AOS and its possible role in any observed effects. Finally, the available evidence indicates that even speakers with severe aphasia show a degree of preserved prosody in functional communication.

Expressive amusia and aphasia: the story of Maurice Ravel.

The French composer, Maurice Ravel, at the peak of his career, showed signs of a progressive disorder that affected his ability to function with verbal and musical language, as noted by the neurologist Théophile Alajouanine. The worsening of the disease led to a craniotomy, performed in 1937, which failed to reveal the cause of his illness, and he died shortly thereafter. A lack of post-mortem neuropathological evidence precluded a definitive diagnosis of the illness, which remained enigmatic. Speculations about the precise diagnosis of Ravel's neurological disease have been largely based on Alajouanine's observations, which included aphasia and amusia, mostly expressive, and ideomotor apraxia, while musical judgement, taste, and memory remained relatively intact, implying different neuroanatomical substrates. A possible subform of frontotemporal lobar degeneration complex was the diagnostic suggestion of many authors. His untimely death deprived the world of this remarkable musician, and the music that remained trapped in his mind.

O compositor francês Maurice Ravel, no ápice de sua carreira, mostrou sinais de uma desordem progressiva que afetou sua capacidade de funcionar com linguagem verbal e musical, como notado pelo neurologista Théophile Alajouanine. O agravamento de sua condição levou a uma craniotomia, efetuada em 1937, que deixou de revelar a causa de sua doença, tendo ele falecido pouco depois. A ausência de evidência neuropatológica pós-morte impediu o diagnóstico definitivo da doença, que permaneceu enigmático. Especulações sobre o diagnóstico preciso da doença neurológica de Ravel foram baseadas sobretudo nas observações de Alajouanine, que compreendiam afasia e amusia, predominantemente expressiva, e também apraxia, enquanto o julgamento, gosto e memória musicais permaneceram relativamente intactos, implicando diferentes substratos neuroanatômicos. A possibilidade de uma subforma do complexo da degenearação lobar frontotemporal foi a sugestão diagnóstica de muitos autores. A sua morte prematura privou o mundo desse notável músico e da música que permaneceu presa em sua mente.

Indicadores tempranos de dispraxia verbal en el inicio tardío: orientaciones para la intervención / Early indicators of childhood apraxia of speech in late talkers: general guidelines to intervention

Resumen Introducción : La población de niños que comienzan con lentitud el desarrollo del lenguaje varía amplia mente, tanto en su perfil inicial como en la respuesta a la intervención. En este sentido, existe un grupo de niños, denominados hablantes tardíos, que continúan mostrando dificultades persistentes en el lenguaje. Al gunos de estos niños muestran signos compatibles con la dispraxia verbal, y que se ponen de manifiesto a lo largo de la intervención. Método : En este trabajo presentamos la diferente respuesta a la intervención de dos perfiles de hablante tardío. Concretamente, se aplicó el programa Target Word©, del centro Hanen, que conjuga la técnica de la estimulación focalizada con la orientación a padres so bre estrategias que promueven el desarrollo del lenguaje. Resultados : Gran parte de la sintomatología mostrada en uno de los dos casos, que experimentó un progreso pobre, coincide con las descripciones retrospectivas de niños posteriormente diagnosticados con dispraxia y pueden considerarse indicadores tempranos del trastor no: ininteligibilidad, inventario consonántico reducido o dificultades en la repetición de palabras. Discusión : La diferente respuesta a la intervención contribuye a la toma de decisiones diagnósticas y a la aplicación temprana de estrategias específicas para la mejora de las habilidades de aprendizaje del habla me diante la incorporación de los principios del aprendizaje motor. Los escasos estudios de intervención en casos de sospecha de dispraxia verbal en la infancia temprana ofrecen resultados prometedores en diversos indicadores de evaluación del habla, y proporcionan a los profesio nales una información valiosa en la que fundamentar la intervención en esta población.

Abstract Introduction : The population of children with slow emergence of language development varies widely, both in their initial profile and in their response to interven tion. In this sense, there is a group of late talkers who continue to show persistent language difficulties, in some cases exhibiting signs compatible with verbal dyspraxia. Method : In this paper we present the different response to intervention of two profiles of late talk ers. Specifically, the Target Word© program (Hanen Centre) was implemented, which is addressed to late-talking children and their families. It combines the technique of focused stimulation with guidance to parents on strategies that stimulate global language development. Results : Much of the symptomatology shown in one case of poor progress coincides with retrospective de scriptions of children subsequently diagnosed with dyspraxia and can be considered early indicators of the disorder: unintelligibility, reduced consonant inventory or difficulties in word repetition. Discussion : The different response to intervention contributes to diagnostic decision making and the early implementation of specific strategies directed to improve speech learning skills by incorporating motor learning principles. The few studies of intervention in suspected verbal dyspraxia in early childhood offer promising re sults on a variety of speech assessment indicators, and provide practitioners with valuable information with which to support the intervention in this population.

Change in Neurocognitive Function in Patients Who Receive CAR-T Cell Therapies: A Steep Hill to Climb.

Immunotherapy with chimeric antigen receptor T (CAR-T) cell therapies has brought substantial improvement in clinical outcomes in patients with relapsed/refractory B cell neoplasms. However, complications such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) limit the therapeutic efficacy of this treatment approach. ICANS can have a broad range of clinical manifestations, while various scoring systems have been developed for its grading. Cognitive decline is prevalent in CAR-T therapy recipients including impaired attention, difficulty in item naming, and writing, agraphia, and executive dysfunction. In this review, we aim to present the diagnostic methods and tests that have been used for the recognition of cognitive impairment in these patients. Moreover, up-to-date data about the duration of cognitive impairment symptoms after the infusion are presented. More research on the risk factors, pathogenesis, preventive measures, and therapy of neurocognitive impairment is crucial for better outcomes for our patients.

Efficacy of LSVT LOUD® on Phonatory Control and Voice Quality in Patients with Primary Progressive Apraxia of Speech: Case Studies.

Primary progressive apraxia of speech (PPAOS) is a neurodegenerative syndrome characterized by the progressive and initially isolated or predominant onset of difficulties in the planning/programming of movements necessary for speech production and can be accompanied by dysarthria. To date, no study has used an evidence-based treatment to address phonation control in patients with PPAOS. The aim of this study was to evaluate the feasibility and efficacy of LSVT LOUD® as a treatment for phonatory control in speakers with PPAOS. Three speakers with PPAOS received LSVT LOUD® therapy, and changes in phonatory control, voice quality and prosody were measured immediately, and one, four and eight weeks after the end of the treatment. Overall, the results suggest that the treatment is feasible and could improve voice quality, intensity, and control in some patients with PPAOS. The generalization of the results is also discussed.

Recovery of gestures for persons with severe non-fluent aphasia and limb apraxia: A long-term follow-up study.

Persons with severe non-fluent aphasia would benefit from using gestures to substitute for their absent powers of speech. The use of gestures, however, is challenging for persons with aphasia and concomitant limb apraxia. Research on the long-term recovery of gestures is scant, and it is unclear whether gesture performance can show recovery over time. This study evaluated the recovery of emblems and tool use pantomimes of persons with severe non-fluent aphasia and limb apraxia after a left hemisphere stroke. The Florida Apraxia Screening Test-Revised (FAST-R) was used for measurements. The test includes 30 gestures to be performed (i) after an oral request, (ii) with the aid of a pictorial cue, or (iii) as an imitation. The gestures were rated on their degree of comprehensibility. The comprehensibility of gestures after an oral request improved significantly in five out of seven participants between the first (1-3 months after the stroke) and the last (3 years after) examination. Improvement continued for all five in the period between six months and three years. The imitation model did improve the comprehensibility of gestures for all participants, whereas the pictorial cue did so just slightly. The skill of producing gestures can improve even in the late phase post-stroke. Because of this potential, we suggest that gesture training should be systematically included in the rehabilitation of communication for persons with severe non-fluent aphasia.

Anterior Minimally Invasive Approach (AMIS) for Total Hip Arthroplasty: Analysis of the First 1000 Consecutive Patients Operated at a High Volume Center.

(1) Background: Direct anterior approach (DAA) has recently acquired popularity through improvements such as the anterior minimally invasive surgical technique (AMIS). This retrospective study examines the first 1000 consecutive THAs performed utilizing the AMIS approach in a high-volume center between 2012 and 2017. (2) Methods: 1000 consecutive THAs performed at a single institution utilizing the AMIS approach were retrospectively analyzed with a minimum five-year follow-up. Full evaluation of demographic information, clinical parameters, intraoperative complications, and radiological examinations are reported. (3) Results: Overall complication rate was 9.4% (94/1000), including 8 dislocations, 57 femoral-cutaneous nerve injuries, 12 intraoperative femoral fractures, 9 infections and 8 leg length discrepancy. Implant survival rates were 98.5% at 1 year, 97.5% at 3 years, 97% at 5 years, and 95.3% at 7 years. Causes of failure included periprosthetic fractures (0.8%), implant dislocations (0.6%), septic loosening (0.5%), aseptic mobilizations (0.2%), and symptomatic limb length discrepancies (0.2%). (4) Conclusions: Controversies persist around the direct anterior approach (DAA) for THA, primarily regarding the increased complications rate during the learning curve. However, this study advocates for widespread adoption of the DAA approach. The results demonstrate acceptable complication rates and remarkable functional outcomes, affirming its viability in the broader orthopedic patient population.

The encoding of speech modes in motor speech disorders: whispered versus normal speech in apraxia of speech and hypokinetic dysarthria.

Speakers with motor speech disorders (MSD) present challenges in speech production, one of them being the difficulty to adapt their speech to different modes. However, it is unclear whether different types of MSD are similarly affected when it comes to adapting their speech to various communication contexts. This study investigates the encoding of speech modes in individuals with AoS following focal brain damage and in individuals with hypokinetic dysarthria (HD) secondary to Parkinson's disease. Participants with mild-to-moderate MSD and their age-matched controls performed a delayed production task of pseudo-words in two speech modes: normal and whispered speech. While overall accuracy did not differ significantly across speech modes, participants with AoS exhibited longer response latencies for whispered speech, reflecting difficulties in the initiation of utterances requiring an unvoiced production. In contrast, participants with HD showed faster response latencies for whispered speech, indicating that this speech mode is easier to encode/control for this population. Acoustic durations followed these same trends, with participants with AoS showing greater lengthening for whispered speech as compared to controls and to participants with HD, while participants with HD exhibited milder lengthening. Contrary to the predictions of speech production models, suggesting that speech mode changes might be particularly difficult in dysarthria, the present results suggest that speech mode adaptation rather seems particularly costly for participants with AoS.

A new method for detecting unilateral spatial neglect with tracing tasks using the Rey-Osterrieth complex figure: a pilot study.

PURPOSE: To explore efficacy of the "Rey-Osterrieth complex figure (ROCF) tracing task" as a new test to detect unilateral spatial neglect (USN). METHODS: Subjects were 40 healthy control (HC) and 20 right brain-damaged patients with (USN + , n = 10) or without USN (USN - , n = 10). After the ROCF copying task, the tracing task was performed under conditions that did not leave any tracing lines on the sample figure. Evaluation used the conventional 36-point scoring system, laterality index (LI) as the ratio of the left and right structure scores, and the number of overlaps for each of the left and right structures scored. RESULTS: In the tracing task, USN + showed a lower LI than HC. Furthermore, left-sided neglect was sometimes more evident than in the copying task. Regarding the total overlapping score, USN + showed a greater score than HC. The right-sided overlapping scores in USN + and USN - were also greater than that in HC. In the right brain-damaged subjects, clinically meaningful correlations were not found between evaluations in the ROCF tracing task and in conventional USN screening tests. Receiver-operating-characteristic analysis to test the power of detection showed moderate performance for the tracing LI (AUC = 0.76, 95% CI = 0.54-0.97), which was greater than that of other tests. Further, the total overlapping score in the tracing task showed sensitivity 0.9 (highest among the tests performed), specificity 0.5, and AUC 0.68 (95% CI = 0.43-0.92). CONCLUSION: The ROCF tracing task might be a convenient method to detect USN and to reveal the extent of spatial working memory impairment.

The neural correlates of limb apraxia: An anatomical likelihood estimation meta-analysis of lesion-symptom mapping studies in brain-damaged patients.

Limb apraxia is a motor disorder frequently observed following a stroke. Apraxic deficits are classically assessed with four tasks: tool use, pantomime of tool use, imitation, and gesture understanding. These tasks are supported by several cognitive processes represented in a left-lateralized brain network including inferior frontal gyrus, inferior parietal lobe (IPL), and lateral occipito-temporal cortex (LOTC). For the past twenty years, voxel-wise lesion symptom mapping (VLSM) studies have been used to unravel the neural correlates associated with apraxia, but none of them has proposed a comprehensive view of the topic. In the present work, we proposed to fill this gap by performing a systematic Anatomic Likelihood Estimation meta-analysis of VLSM studies which included tasks traditionally used to assess apraxia. We found that the IPL was crucial for all the tasks. Moreover, lesions within the LOTC were more associated with imitation deficits than tool use or pantomime, confirming its important role in higher visual processing. Our results questioned traditional neurocognitive models on apraxia and may have important clinical implications.

Differential spectral characteristics of the Spanish fricative /s/ in the articulation of individuals with dysarthria and apraxia of speech.

PURPOSE: This study examines whether there are differences in the speech of speakers with dysarthria, speakers with apraxia and healthy speakers in spectral acoustic measures during production of the central-peninsular Spanish alveolar sibilant fricative /s/. METHOD: To this end, production of the sibilant was analyzed in 20 subjects with dysarthria, 8 with apraxia of speech and 28 healthy speakers. Participants produced 12 sV(C) words. The variables compared across groups were the fricative's spectral amplitude difference (AmpD) and spectral moments in the temporal midpoint of fricative execution. RESULTS: The results indicate that individuals with dysarthria can be distinguished from healthy speakers in terms of the spectral characteristics AmpD, standard deviation (SD), center of gravity (CoG) and skewness, the last two in context with unrounded vowel, while no differences in kurtosis were detected. Participants with AoS group differ significantly from healthy speaker group in AmpD, SD and CoG and Kurtosis, the first one followed unrounded vowel and the latter two followed by rounded vowels. In addition, speakers with apraxia of speech group returned significant differences with respect to speakers with dysarthria group in AmpD, CoG and skewness. CONCLUSIONS: The differences found between the groups in the measures studied as a function of the type of vowel context could provide insights into the distinctive manifestations of motor speech disorders, contributing to the differential diagnosis between apraxia and dysarthria in motor control processes.

Progression to corticobasal syndrome: a longitudinal study of patients with nonfluent primary progressive aphasia and primary progressive apraxia of speech.

BACKGROUND AND OBJECTIVES: Nonfluent variant primary progressive aphasia (nfvPPA) and primary progressive apraxia of speech (PPAOS) can be precursors to corticobasal syndrome (CBS). Details on their progression remain unclear. We aimed to examine the clinical and neuroimaging evolution of nfvPPA and PPAOS into CBS. METHODS: We conducted a retrospective longitudinal study in 140 nfvPPA or PPAOS patients and applied the consensus criteria for possible and probable CBS for every visit, evaluating limb rigidity, akinesia, limb dystonia, myoclonus, ideomotor apraxia, alien limb phenomenon, and nonverbal oral apraxia (NVOA). Given the association of NVOA with AOS, we also modified the CBS criteria by excluding NVOA and assigned every patient to either a progressors or non-progressors group. We evaluated the frequency of every CBS feature by year from disease onset, and assessed gray and white matter volume loss using SPM12. RESULTS: Asymmetric akinesia, NVOA, and limb apraxia were the most common CBS features that developed; while limb dystonia, myoclonus, and alien limb were rare. Eighty-two patients progressed to possible CBS; only four to probable CBS. nfvPPA and PPAOS had a similar proportion of progressors, although nfvPPA progressed to CBS earlier (p-value = 0.046), driven by an early appearance of limb apraxia (p-value = 0.0041). The non-progressors and progressors both showed premotor/motor cortex involvement at baseline, with spread into prefrontal cortex over time. DISCUSSION: An important proportion of patients with nfvPPA and PPAOS progress to possible CBS, while they rarely develop features of probable CBS even after long follow-up.