BACKGROUND Carotid-cavernous fistulas (CCFs) are abnormal arteriovenous communications between the carotid artery and cavernous sinus. They may be direct or indirect and commonly present with both ocular and neurovascular symptoms. Endovascular embolization is the main treatment, with high rates of fistula obliteration and clinical improvement. Although generally safe, complications can occur, including cranial nerve dysfunction and vascular injury. Endocrine complications following carotid-cavernous fistula embolization are exceedingly rare. To our knowledge, only 1 case of syndrome of inappropriate antidiuresis (SIAD) after Onyx embolization has been reported in the literature. CASE REPORT A 72-year-old woman developed severe symptomatic SIAD 9 days after transarterial Onyx embolization of an indirect CCF. The procedure was successful but associated with worsening of preexisting left abducens nerve paresis. She subsequently re-presented with dizziness, truncal ataxia, and confusion, which resulted in a fall involving wrist fracture but no head strike. Investigations demonstrated profound hypotonic euvolemic hyponatremia with elevated urine osmolality and urine sodium, suggestive of SIAD. The absence of hypovolemia, polyuria, and a negative fluid balance argued against cerebral salt wasting. Adrenal insufficiency, hypothyroidism, and other causes were excluded. Treatment with hypertonic saline and fluid restriction resulted in gradual sodium correction and complete neurological recovery. CONCLUSIONS Transient hypothalamic-pituitary dysfunction related to Onyx-associated local mass effect and hemodynamic changes may represent a plausible mechanism. This case highlights delayed-onset SIAD as a rare but clinically significant complication temporally associated with CCF embolization. The findings support consideration of both early and delayed electrolyte monitoring, particularly within the first 1 to 2 weeks after the procedure.

Acute positional vertigo is a common neurological presentation, which is often assumed to be due to benign peripheral vestibular causes. This paper presents the case of a woman in her late 30s who presented with brief, recurrent, position-triggered vertigo. She had no headache, neck pain, trauma history, or vascular risk factors. The clinical history closely resembled benign paroxysmal positional vertigo. However, neurological examination revealed subtle central signs: internuclear ophthalmoplegia and cerebellar ataxia. Brain imaging demonstrated infarction in the left cerebellar hemisphere. Brainstem imaging showed no corresponding abnormalities. Vascular imaging revealed extracranial left vertebral artery dissection. The patient condition was managed conservatively with antiplatelet therapy and a statin. Her symptoms resolved spontaneously, with no recurrence of vertigo on follow-up. This case illustrates that vertebral artery dissection may present without pain and highlights the importance of careful neurological examination in patients with acute vertigo.

A 70-year-old woman presented with slowly progressive mobility difficulty and involuntary jerking movements, which had started at age 55 years. On examination, she had generalised action-induced myoclonus and gait ataxia. Extensive investigation over 10 years had not given a diagnosis. Genetic testing was re-visited and she was found to carry a likely pathogenic variant and a variant of unknown significance in the neuraminidase gene. Dermal fibroblast culture identified significantly reduced neuraminidase activity in keeping with a diagnosis of late-onset sialidosis. Taking into account biochemical evidence and the clinical phenotype, the identified variants have been reclassified as pathogenic and likely pathogenic. This case shows the value in revisiting genetic testing in unresolved cases and the need to be aware of the presentation of inherited rare metabolic disorders in later life.

Celiac disease (CD) is a chronic immune-mediated enteropathy triggered by gluten ingestion in genetically susceptible individuals. While traditionally associated with gastrointestinal (GI) symptoms, CD is increasingly recognized as a systemic disorder with significant neurological involvement. A growing body of evidence links CD to a broad spectrum of neurological manifestations, including gluten ataxia (GA), peripheral neuropathy (PN), epilepsy, migraine, myoclonic disorders, and cognitive impairment. These symptoms may precede or occur independently of GI symptoms, complicating diagnosis and delaying treatment. The underlying mechanisms are multifactorial, involving autoantibody cross-reactivity, neuroinflammation, increased permeability of the intestinal and blood-brain barrier (BBB), gut dysbiosis, and micronutrient deficiencies. This review synthesizes current insights into the pathophysiological basis of CD-related neurological disorders. We also explore the therapeutic impact of a strict gluten-free diet (GFD) on CD-related neurological manifestations. Early recognition of neurological signs and their prompt management are essential to mitigate irreversible neural injury and improve long-term outcomes in these patients. Given the potential for symptom reversibility with dietary treatment, routine screening for CD should be considered in patients presenting with idiopathic neurological syndromes, even in the absence of GI symptoms.

Generalized subcutaneous emphysema (GSE) is an uncommon clinical presentation in equids, typically associated with penetrating trauma and rarely compromising systemic health. This case report documents a 4-year-old working mule presenting with diffuse subcutaneous emphysema secondary to an axillary penetrating wound in the right forelimb. Clinical examination revealed pronounced crepitus without concurrent ataxia, dyspnea, dehydration, or gastrointestinal dysfunction. Diagnostic investigations, including ultrasonography, radiography, complete blood count, paracentesis, and bacterial culture, yielded unremarkable hematological findings and no microbial growth. The wound was managed via local debridement, with adjunct systemic therapy, including penicillin G and flunixin meglumine. Complete resolution occurred within five days under stall rest. This case underscores that generalized subcutaneous emphysema in mules may represent a benign, self-limiting condition when infectious etiologies are excluded. Conservative management, including compulsory rest and anti-inflammatory therapy, can facilitate spontaneous resolution while mitigating risks of pneumothorax or gas gangrene. The rarity of non-infectious generalized subcutaneous emphysema in equids warrants further etiopathological investigation to establish species-specific prognostic criteria.

An early adolescent boy, born to a consanguineously married couple, with mild baseline developmental delay, presented with fever-triggered acute encephalopathy manifesting as ataxia, tremors and seizures. Neuroimaging revealed multifocal, symmetric involvement of the insular cortex, basal ganglia, temporo-occipital regions and cerebellum with diffusion restriction. Extensive infectious, autoimmune and metabolic evaluation during the first episode was inconclusive, and he was treated as immune-mediated encephalitis with partial recovery. Three months later, febrile illness precipitated a severe relapse with neurological regression, movement disorder and progressive cerebellar atrophy on follow-up imaging. Given the relapsing fever-triggered course, baseline developmental delay, incomplete recovery, negative autoimmune workup and progressive neuroimaging changes without new inflammatory lesions, a genetic aetiology was suspected. Genetic testing identified a homozygous variant in the NUP214 gene, supporting a diagnosis of acute infection-induced encephalopathy type 9. This case highlights the importance of considering genetic susceptibility in children with recurrent infection-triggered encephalopathy and atypical recovery.

Gurltia paralysans is an angio-neurotropic metastrongyloid nematode and the etiologic agent of feline gurltiosis, a rare but emerging parasitic disease in domestic and wild felids. Infection by G. paralysans leads to progressive neurological deficits including ataxia, paraparesis, and fecal/urinary incontinence. This report describes the first confirmed case of feline gurltiosis in Santa Catarina, Brazil, expanding the known geographic distribution of the disease. A 2-years-old domestic cat presented with a six-month history of progressive pelvic limb paralysis and was euthanized due to poor prognosis. Necropsy and histopathology revealed typical lesions of G. paralysans infection in spinal cord samples, such as dilated veins containing metastrongyloid nematodes, thrombosis, and Wallerian degeneration. The G. paralysans DNA was detected by semi-nested PCR for the gene 28S rRNA in a paraffin-embedded spinal cord sample. This case underscores the need for heightened clinical suspicion of gurltiosis in cats with chronic myelopathies, particularly in rural areas of South America.

Neurons accumulate somatic mutations with age, but how mutation processes vary among neuronal types remains unclear. Characterizing this variability may elucidate the role of genome integrity in brain function and disease and reveal determinants of mutation rates and patterns. Using high-fidelity duplex DNA sequencing, we profiled somatic mutations across the lifespan in human cerebellar Purkinje and granule neurons, which differ markedly in size and physiology. Surprisingly, they exhibited similar substitution rates, including rates of SBS5, the body's predominant mutational signature, whose mechanism is unknown. However, their substitution patterns and insertion/deletion rates and patterns differed, with transcription associated with these differences. In surviving granule neurons from five cerebellar ataxias, we detected only a small disease effect on mutation profiles. Our work indicates that neuronal types can differ in aging-related mutagenesis and that key features distinguishing Purkinje and granule neurons are unlikely, in these neurons, to be major determinants of SBS5 activity.

Objectively quantifying cerebellar motor dysfunction remains a challenge in clinical trials. The Adaptability Index, derived from the Prism Adaptation Test, evaluates motor learning but lacks multicenter validation. We aimed to validate the Adaptability Index as a robust biomarker across multiple hospitals and investigate its relationship with the Scale for the Assessment and Rating of Ataxia. We enrolled 74 patients with cerebellar degeneration across seven hospitals using a standardized touchscreen system. We analyzed the correlation between Adaptability Index and the Scale for the Assessment and Rating of Ataxia and evaluated inter-hospital robustness using Linear Mixed-effects Modeling. Consistency of Adaptability Index variance between distinct genotypes (Spinocerebellar Ataxia type 6 and type 31) was assessed using Levene's test and normalized standard deviations. The Adaptability Index correlated negatively with the Scale for the Assessment and Rating of Ataxia (r = - 0.364, p < 0.01). Notably, Linear Mixed-effects Modeling revealed negligible inter-hospital variance, confirming robustness against site-specific biases. Levene's test indicated consistent Adaptability Index variance across these genotypes (p = 0.41). However, the Adaptability Index exhibited higher resolution than the Scale for the Assessment and Rating of Ataxia in detecting phenotypic variability (larger normalized standard deviations), particularly in the Spinocerebellar Ataxia type 31 cohort, likely reflecting cerebellar motor learning capacity distinct from motor execution deficits. The Adaptability Index is a valid, genotype-stable, and site-independent biomarker of cerebellar motor learning. Its high resolution and robustness make it a promising objective endpoint for multicenter interventional trials targeting cerebellar dysfunction.