Inherited homocystinuria is a rare autosomal recessive aminoacidopathy which through early diagnosis can prevent its severe neurologic and vascular complications. Here we report a 9-year-old girl with homocystinuria, presenting with sequential symptoms of bilateral lens dislocation, skeletal complication, and eventually dystonia from the age of 4 years. Laboratory evaluation revealed severe high serum homocysteine level. Although pathophysiologically unexplained, evidence of deep white matter watershed infarct along with remarkable ipsilateral carotid stenosis was detected on the contralateral side of the dystonia in the neuroimaging. Treatment with high dose of pyridoxine relieved limb and gait dystonia significantly, while carotid stenosis remained unchanged. Therefore, homocysteine might have both structural and irreversible effect and functional and reversible impact that could be overcome even in late stages.

A 39-year-old Iranian female patient who was a known case of primary cervical dystonia since 10 years ago presented to a private office for Dysport injection. The patients experienced severe dysphagia after inferior alveolar nerve block which was preceded by cervical botolinum toxin injection. A possible synergistic effect of botolinum toxin and lidocaine to produce severe dysphagia is presented in this case report.

Background Fear of falling (FoF) is defined as a lasting concern about falling that causes a person to limit or even stop the daily activities that he/she is capable of. 70% of Parkinson’s disease (PD) patients report activity limitations due to FoF. Timely identification of FoF is critical to prevent its additional adverse effects on the quality of life. Self-report questionnaires are commonly used to evaluate the FoF, which may be prone to human error. Objectives In this study, we attempted to identify a new postural stability-indicator to objectively predict the intensity of FoF and its related behavior(s) in PD patients. Methods Thirty-eight PD patients participated in the study (mean age, 61.2 years), among whom 10 (26.32%) were identified with low FoF and the rest (73.68%) with high FoF, based on Falls Efficacy Scale-International (FES-I). We used a limit of stability task calibrated to each individual and investigated the postural strategies to predict the intensity of FoF. New parameters (FTRi’s; functional time ratio) were extracted based on the center of pressure presence pattern in different rectangular areas (i = 1, 2, and 3). The task was performed on two heights to investigate FoF related behavior(s). Results FTR 1/2 (the ratio between FTR1 and FTR2) was strongly correlated with the FES-I (r = − 0.63, P < 0.001), Pull Test (r = − 0.65, P < 0.001), Timed Up and Go test (r = − 0.57, P < 0.001), and Berg Balance Scale (r = 0.62, P < 0.001). The model of FTR1/2 was identified as a best-fitting model to predicting the intensity of FoF in PD participants (sensitivity = 96.43%, specificity = 80%), using a threshold level of ≤ 2.83. Conclusions Using the proposed assessment technique we can accurately predict the intensity of FoF in PD patients. Also, The FTR1/2 index can be potentially considered as a mechanical biomarker to sense the FoF-related postural instability in PD patients.

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