cover image European Journal of Neurology

European Journal of Neurology

2026 - Volume 33
Issue 1 | January 2026

ORIGINAL ARTICLE

Background

Hereditary Transthyretin Amyloidosis with polyneuropathy (ATTRv‐PN) is an autosomal dominant disorder characterized by gene mutations, causing amyloid fibril deposition in peripheral nerves. Significant CNS involvement has been noted, emphasizing the necessity for advanced neuroimaging tools for early detection of CNS damage in ATTRv.

Methods

Comprehensive clinical assessments and multimodal MRI techniques, including FreeSurfer, TBSS and microbleed analysis, were utilized. The cohorts comprised 30 symptomatic patients (ATTRv‐PN), 19 presymptomatic patients (pre‐ATTRv‐PN), classified based on neuropathic signs, and 44 age‐ and sex‐matched controls. For cognitive assessment, we utilized the Addenbrooke's Cognitive Examination‐Revised.

Results

The ATTRv‐PN group had an average age of 51 years, while the pre‐ATTRv‐PN group averaged 41 years, with a sex ratio of 35% men to 65% women. Symptomatic patients experienced an average disease duration of 5 years, predominantly featuring the p.Val50Met genotype (73%). Brain imaging showed diffuse subcortical white matter alterations in ATTRv‐PN, while cortical thinning and microbleeds were infrequent. Cognitive assessments revealed significant differences, with symptomatic scoring lower in memory and verbal fluency than presymptomatic.

Conclusion

ATTRv‐PN involves cerebral white matter microstructural damage from early stages. Multimodal MRI serves as an accurate, non‐invasive tool for detecting CNS damage, improving our understanding of the disease spectrum.

LETTER TO THE EDITOR

Interpreting the Mediating Variable of PPP Through Appropriate Design and Rigorous Measurement Methods

ORIGINAL ARTICLE

Background

Distinguishing between distal myopathies (DMs) and distal hereditary motor neuropathies (dHMNs) can be challenging because clinical, EMG and biopsy findings sometimes overlap. This study aims to identify distinctive muscle MRI features that can guide the diagnosis.

Methods

We collected clinical, genetic and muscle MRI data from patients with a confirmed diagnosis of DM and dHMN. We analyzed potential MRI characteristics to distinguish these conditions and to guide molecular diagnosis, such as the texture and pattern of infiltration.

Results

Seventy‐eight (71.5%) patients diagnosed with DMs and thirty‐one (28.4%) with dHMNs were included. A length‐dependent pattern of muscle involvement, a distal to proximal gradient of fat replacement along the length of the muscles and severe and widespread involvement of foot muscles were more common in patients with dHMNs. Muscle hypertrophy and asymmetry were more frequently observed in the DMs. A reticular pattern of fat infiltration was exclusive to patients with dHMNs, while the moth‐eaten pattern predominated in DMs. Muscle islands were more commonly identified in dHMNs (54.8%) but were also observed in 32% of patients with DMs.

Conclusions

Analysis of MRI features can help distinguish between DMs and dHMNs. A reticular pattern is an early feature of dHMNs while muscle islands are identified in advanced stages and in some forms of DMs, though not specific to neurogenic conditions. We recommend including foot muscles in the MRI protocol as they show extensive involvement in most dHMNs, while in DMs their involvement correlates with greater fatty infiltration of lower leg muscles.

LETTER TO THE EDITOR

Clarifying Order and Carry‐Over Considerations in Dual‐Target MRgFUS for Parkinson's Disease

ORIGINAL ARTICLE

Background

Studies on interrater agreement in MRI analysis for patients experiencing a first clinical episode suggestive of multiple sclerosis (MS) are limited and outdated. This study aimed to evaluate interrater agreement for lesion identification in the brain, optic nerve, and spinal cord, and to assess variability in applying the 2017 and 2024 McDonald criteria.

Methods

Seventy‐eight patients underwent a standardized multisequence 3 Tesla MRI of the brain, optic nerves, and spinal cord, analyzed by three readers with varying expertise. Lesions were categorized based on location according to McDonald criteria. Interrater variability was measured using Cohen's κ for pairwise reader comparisons and Fleiss κ for overall agreement.

Results

Interrater agreement ranged from slight to fair for total lesion count and moderate to substantial for lesion presence. The highest agreement occurred for spinal cord lesions (κ = 0.84), periventricular T2 lesions (κ = 0.70), and gadolinium‐enhancing brain lesions (κ = 0.75). Classification agreement based on diagnostic criteria was substantial between the 2017 and 2024 McDonald criteria revisions (κ = 0.65).

Conclusions

Despite advanced standardized imaging protocols at 3 T, interrater agreement regarding lesion counts does not improve substantially. However, agreement in classifying lesions according to diagnostic criteria is consistent between the 2017 and 2024 criteria.

LETTER TO THE EDITOR

Response to the Letter to the Editor: “Reaffirming Caution—The Unacceptable Vasoconstrictive Risk of CGRP‐Related Therapies in Moyamoya Angiopathy”

ORIGINAL ARTICLE

Background

Hyposmia is present in most patients with Parkinson's disease (PD), whereas olfaction is usually preserved in its diagnostic mimics. To address the limited evidence from smaller studies, we conducted a meta‐analysis on the diagnostic accuracy of olfactory testing in differentiating PD from clinical look‐alikes.

Methods

A systematic search was performed in PubMed and Web of Science according to the PRISMA guidelines. Studies describing results of validated smell tests in PD patients and at least one differential diagnosis were included. The risk of bias and applicability was assessed with the QUADAS‐2 tool. For data synthesis, a hierarchical regression model was employed.

Results

Of 787 publications, 23 studies describing 1957 PD patients, 462 patients with atypical parkinsonian disorders, 239 patients with essential tremor, and 43 patients with secondary parkinsonism were included. The meta‐analysis demonstrated a sensitivity of 79% (95% confidence interval [CI]: 72%–84%) and a specificity of 81% (95% CI: 73%–86%) for olfactory dysfunction to differentiate PD from all other disorders combined. Additional analyses showed consistent sensitivities across sub‐analyses, with lowest specificities for the distinction from progressive supranuclear palsy, 64% (95% CI: 55%–72%), and highest from essential tremor, 92% (95% CI: 84%–96%).

Conclusion

Our findings indicate that olfactory testing shows moderate to good diagnostic accuracy in differentiating PD from its main differential diagnoses. While results of olfactory testing alone are insufficient for a definite distinction of PD from non‐PD parkinsonism, it represents an easy‐to‐use and inexpensive test that may be used in combination with other diagnostic tools.

ORIGINAL ARTICLE

Background

Hereditary spastic paraparesis (HSP) encompasses a genetically and clinically heterogeneous group of neurodegenerative disorders, primarily characterized by progressive lower limb spasticity and weakness of the lower limbs. Although more than 80 genes have been associated with HSP, achieving definite genetic diagnosis remains challenging, limiting effective patient care, genetic counseling, and understanding of genotype–phenotype correlations. This study aimed to investigate the diagnostic yield of clinical exome sequencing (CES) in a cohort of Spanish individuals with suspected HSP and to explore genotype–phenotype correlations.

Methods

A total of 139 non‐related Spanish individuals with HSP underwent standardized clinical evaluation and CES. Genetic analyses were performed using a virtual panel containing 129 HSP‐associated genes, complemented by phenotype‐driven filtering through the Human Phenotype Ontology. Statistical analyses were performed on core clinical and paraclinical features.

Results

After clinical review, 108 index cases were included. Male patients were slightly more represented and mean age at onset was 33 years. Pure HSP forms were more prevalent. The most frequent presenting symptoms were gait disturbance and recurrent falls. A genetic diagnosis was achieved in 57 patients (52,8%), with and being the most frequently mutated genes. In total, pathogenic/likely pathogenic variants were identified across 21 genes, including 8 novel variants. HSP with autosomal recessive inheritance was more common than autosomal dominant (29 vs. 25 cases), while dominant/recessive X‐linked disease forms were rare (3 cases).

Conclusions

CES combined with HPO‐based filtering is an effective strategy for achieving genetic diagnosis in patients with suspicion of HSP.

ORIGINAL ARTICLE

Background

Disorders of consciousness (DoC) pose significant challenges in clinical diagnosis and treatment. This study aims to investigate the relationship between consciousness levels and the brainstem‐cortical white matter tracts in DoC patients resulting from focal brainstem injury using diffusion tensor imaging (DTI).

Methods

DTI data of DoC patients with focal brainstem injury and healthy volunteers were retrospectively collected. White matter tractography was performed to reconstruct brainstem‐cortical projections. The number of streamlines, total volume, and fractional anisotropy (FA) were analyzed from the perspective of global brain, physiological pathways, and functional networks. The relationship between these measurements and consciousness levels was investigated.

Results

A cohort of 28 DoC patients and 32 healthy controls were included in the analysis. DoC patients exhibited significant reductions in the number of streamlines in global brainstem‐cortical projections compared to controls. However, the total volume and FA of these fibers were relatively preserved. Specific pathways such as the corticospinal tract and frontoparietal tract showed marked reductions in streamline counts. Significant reductions in streamline counts were also observed in the somatomotor and frontoparietal networks. No significant changes in mean FA were observed across different physiological pathways and brain networks. Correlation analyses revealed significant associations between consciousness levels and structural connections in the frontoparietal tract and frontoparietal network.

Conclusion

This study highlights the impact of focal brainstem injury on global brain structural connectivity in DoC patients. Despite significant reductions in streamline counts, the preservation of FA suggests maintained microstructural integrity in surviving fibers.

ORIGINAL ARTICLE

Background

Facioscapulohumeral dystrophy (FSHD) and Myasthenia Gravis (MG) are well‐known rare neuromuscular diseases of respectively genetic and acquired origin. Among muscular dystrophies, the co‐occurrence of MG with FSHD is the most common, representing a non‐negligible “double trouble”. Here, we aim to describe a series of patients with coexistence of these two rare disorders and combine this with a review of the literature to identify common elements which might provide useful clues when evaluating a FSHD patient with uncommon clinical presentation compatible with MG.

Methods

We retrospectively collected demographic, clinical, and laboratory data of patients affected by both FSHD and MG followed at the Nice University Center, and we performed a review of the literature.

Results

We identified 10 patients in our cohort, 7 females. All patients have a D4Z4 4qA allele of 7–10 RU, a disease onset > 45 years and a mean FSHD score of 9.6 ± 2 at the last evaluation. The mean age of onset of MG was 68.5 ± 7.6 years; all patients presented with anti‐AChR antibodies and without thymic pathology, and MG appeared in all but two patients after FSHD. We identified 9 case reports in the literature. All of them presented with AChR positivity. The majority of them presented with a late and very late onset MG and without thymic pathology.

Conclusions

Our results underline the need for careful clinical evaluation to identify uncommon features, especially in elderly FSHD patients carrying a D4Z4 4qA allele of 7–10 RU to exclude the coexistence of other treatable neuromuscular conditions.

ORIGINAL ARTICLE

Objectives

Idiopathic intracranial hypertension (IIH) is characterized by increased intracranial pressure and papilledema. If left untreated, it can lead to vision loss, and, timely detection of papilledema is of paramount importance. Direct ophthalmoscopy can be difficult to perform and interpret for non‐ophthalmologists. Therefore, this study aimed to investigate the impact of combined fundus photography and perimetry (CFPP) on patients with suspicion of new‐onset IIH or IIH follow‐up.

Method

The study was based on a cross‐sectional, retrospective chart review of all patients who underwent CFPP examination due to suspicion of new‐onset IIH or IIH follow‐up at the Danish Headache Center between 2020 and 2023.

Results

258 patients were included for analysis, 92% females aged 17–72 years (mean age: 35.8 years). CFPP was performed due to clinical suspicion of new‐onset IIH (38%), worsening/relapse of IIH (24%), assurance check in known IIH (19%), subjective symptoms (5%) or other reasons (14%). Overall, 62% had normal fundus photos, 21% had optic disc edema, 10% had other coincidental findings in the retina and/or optic disc, and 6% had an optic disc status unchanged from previous examinations. The use of CFPP confirmed the suspicion of IIH in 8% of patients and disproved it in 40% of patients. The CFPP results changed the treatment plan in 28% and caused referral to a neuroophthalmologist in 16% of patients.

Conclusion

CFPP can be used as a time‐ and resource‐saving screening tool in headache patients with suspicion of new‐onset IIH or follow‐up in a tertiary neurology setting.

ISSUE INFORMATION

Issue Information

LETTER TO THE EDITOR

Letter to the Editor: Reaffirming Caution—The Unacceptable Vasoconstrictive Risk of CGRP‐Related Therapies in Moyamoya Angiopathy

ORIGINAL ARTICLE

Background

Cryptogenic strokes (CS) represent one third of admissions for stroke. Silent paroxysmal atrial fibrillation (PAF) is the underlying cause of a significant proportion of cases. The use of internal loop recorders (ILR) after CS has shown controversial results, remaining unclear in guidelines. Subtle ultrasound left atrium (LA) anomalies may help select patients more prone to suffer from silent PAF who can benefit from an ILR.

Methods

Randomized, controlled, parallel‐arm, open‐label trial of patients with CS. We evaluated the efficacy of early ILR for detection of silent PAF episodes compared to standard care. Clinical/ultrasound predictors of PAF were studied. The presence of subtle LA anomalies (any of: LA dilatation, maximum systolic global longitudinal strain < 21%, atrial contraction strain < 13%, atrial ejection fraction < 55%) was used in a pre‐specified subgroup analysis.

Results

Fifty‐nine CS patients were included (52.5% to ILR and 47.5% to standard care). There were no statistically significant differences among groups regarding baseline characteristics. Median follow‐up was 377 days. The diagnosis of silent PAF was made in 43.3% in the ILR group compared to 7.1% in the control group (HR 7.47, 95% CI 1.68–31.19,  = 0.008). Most PAF events were detected in the 100 days following ILR implantation. In patients with normal LA, PAF was observed in 23% versus 7%, while in patients with abnormal LA, PAF was diagnosed in 58.8% versus 7.7%.

Conclusions

An ILR implanted early after CS improves the detection of PAF compared to standard care. Individuals with abnormal LA features may benefit the most from ILR.

ORIGINAL ARTICLE

Context

B‐cell‐depleting therapies such as rituximab and newer anti‐CD20 agents may impair humoral immune responses and reduce the reliability of serological testing. This systematic review aims to summarize reported cases of Lyme borreliosis and relapsing fever (RF) infections in patients receiving B‐cell‐depleting therapies, focusing on clinical manifestations, diagnostic challenges, and treatment outcomes.

Methods

A systematic literature search was conducted using PubMed and the Web of Science Core Collection employing search terms linking B‐cell‐depleting therapies to Lyme borreliosis and to RF infections.

Results

The most reported cases in the literature were neurological infections due to there were 11 cases of Lyme neuroborreliosis and 8 cases of neurological infections due to reported. Lyme neuroborreliosis cases all exhibited negative serology. Pleocytosis of cerebrospinal fluid (CSF) was, however, always present, and PCR could confirm the diagnosis in 8 cases. Diagnosis in all cases relied exclusively on direct detection methods. All patients responded to standard antibiotic regimens, although persistent symptoms were reported in some cases. The other infections were 7 erythema migrans (EM), 4 disseminated Lyme borreliosis, and 3 cases of relapsing fever.

Conclusion

Neurological Borrelia infections may be underrecognized in patients on B cell‐depleting therapies due to atypical presentations and negative serologies. Early consideration of direct diagnostic methods such as PCR or indirect methods such as CSF CXCL13 levels is critical. Neurologists should maintain a high index of suspicion for infections in immunocompromised patients presenting with CSF pleocytosis and neurological symptoms.

LETTER TO THE EDITOR

The Importance of Reliable Self‐Report Measures to Test PPPD Mechanisms

ORIGINAL ARTICLE

Background

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy (GFAP‐A) is a newly recognized autoimmune disorder of the central nervous system, characterized by the presence of GFAP‐IgG in the cerebrospinal fluid. Although corticosteroid therapy typically yields favorable responses, limited therapeutic efficacy is observed in some patients who subsequently develop poor clinical outcomes. This study aimed to identify prognostic factors using clinical data of patients with GFAP‐A.

Methods

This retrospective cohort study included 233 patients with GFAP‐A, who were followed up for more than 6 months. At 6 months after admission, patients were classified into unfavorable outcome [modified Rankin Scale (mRS) score ≥ 3] and favorable outcome (mRS ≤ 2) groups. Clinical data were compared between the two groups using univariate analysis. Variables that showed statistically significant differences were subsequently analyzed using multiple regression analysis to identify the individual contribution of each predictor to the unfavorable outcomes at 6 months after admission.

Results

In the multiple regression analysis, age ( < 0.001), seizures ( = 0.050), motor paralysis ( = 0.042), and mRS scores at admission ( = 0.001) were positively associated with unfavorable outcomes. In contrast, fever ( = 0.020) was negatively associated with unfavorable outcomes.

Conclusions

In conclusion, advanced age, comorbid seizures, comorbid motor paralysis, lack of febrile episodes, and higher mRS scores at admission were associated with unfavorable outcomes in our cohort. These findings highlight the need for future studies to elucidate the underlying pathophysiological mechanisms associated with these clinical characteristics and to develop effective alternatives to corticosteroid therapy.

REVIEW ARTICLE

Background

Deep brain stimulation (DBS) is an essential treatment option for disabling segmental or generalized dystonia. An underlying monogenic etiology is increasingly recognized as an important predictor of DBS outcomes. Moreover, the genetic background of dystonia is continuously expanding, posing new challenges in the tailored counseling of patients regarding advanced therapies.

Methods

To improve the quality of available evidence on the efficacy of DBS for treating monogenic dystonia, we conducted a systematic review in accordance with PRISMA guidelines. We applied a rigorous methodology and maximized the amount of information provided by including all patients, regardless of age or applied rating scale.

Results

Our findings confirm the high probability of a good DBS outcome in patients harboring , and variants. An intermediate response was associated with and variants. A particularly favorable outcome with > 80% improvement in dystonia symptoms was associated with a subset of DYT‐ patients and few cases with ‐, ‐, and ‐related disease. Poor study quality, non‐systematic assessment of DBS response, and pooling of patients with different genetic etiologies were among the encountered limitations.

Conclusions

Based on the collected evidence, we formulated recommendations for applying DBS in monogenic dystonia. Our findings, together with the cumulative literature, advocate the introduction of genetic testing in the pre‐DBS work‐up. They furthermore highlight the need to implement and report on systematic assessments of DBS outcomes, including mandatory patient‐reported outcomes. These steps will ensure optimal counseling and continuous improvement in the care of patients with monogenic dystonia.

LETTER TO THE EDITOR

Signs of Intracranial Hypertension in Chronic Inflammatory Polyradiculoneuropathies—A Cross Sectional Cohort Study

LETTER TO THE EDITOR

Reply to the Comment by Zhang et al

ORIGINAL ARTICLE

Objective

Parkinson's disease (PD) affects both motor and non‐motor functions, including facial expressivity. While subthalamic nucleus deep brain stimulation (STN‐DBS) is effective for motor symptoms, its impact on facial expression remains unclear. This study aimed to objectively assess the impact of DBS on facial movement timing and amplitude using objective facial landmark‐based motion analysis.

Methods

We analyzed 10 PD patients with STN‐DBS (≥ 3 years) and 10 age‐ and sex‐matched controls. Standardized video recordings were obtained using a fixed camera setup. Facial movements were analyzed using objective facial landmark‐based motion analysis implemented via a pre‐trained facial landmark detection framework (Mediapipe), extracting 468 facial landmarks across approximately 1800 frames per recording. Key facial parameters, including smile completion time and region‐specific ranges of motion (ROM), were quantified.

Results

DBS significantly increased oral commissure and frontal ROM ( < 0.05) while reducing smile completion time ( = 0.003). However, PD patients' smiles remained slower than those of controls (0.64 ± 0.21 s vs. 0.49 ± 0.09 s;  = 0.019), indicating incomplete normalization of facial expressivity. Medial eyebrow and palpebral movements showed no significant differences ( > 0.05).

Conclusion

STN‐DBS enhances the amplitude of some facial movements but does not fully restore temporal dynamics of facial expression. Persistent delays in smile execution suggest that aspects of facial motor control may remain impaired despite effective stimulation. Objective facial landmark‐based motion analysis provides a sensitive tool for detecting subtle alterations in facial motor dynamics and may support future studies investigating complementary strategies to optimize motor expressivity in PD.

LETTER TO THE EDITOR

Moving Beyond Population‐Level Analyses to Characterize Individual Heterogeneity in CMAP Responses Would Enhance the Assessment of Its Clinical Utility

ORIGINAL ARTICLE

Background

Clinical guidelines for treating myasthenia gravis (MG) recommend avoiding certain therapies because of a risk of exacerbating MG. We evaluated use of statins and other classically contraindicated therapies and their impact on healthcare outcomes among patients with MG in France.

Methods

This was an observational, retrospective, longitudinal cohort study using data from the French national health insurance database. Adult patients with MG‐related claims from 2013 to 2020 were included. The first MG claim date was the index date, with follow‐up until end‐of‐study or death. Multivariable regression models evaluated the risk of intensive care unit (ICU) admission for MG or death during periods of exposure versus nonexposure to contraindicated treatments.

Results

Of 14,459 individuals with MG, 12,954 (89.6%) received a contraindicated treatment during follow‐up, and 4160 (28.8%) received statins. In multivariable regression analyses, exposure to any contraindicated treatment was not significantly associated with risk of ICU admission for MG (hazard ratio [HR] 1.038; 95% confidence interval [CI] 0.968–1.113;  = not significant) but was associated with significantly higher risk of death (HR 1.167; 95% CI 1.075–1.266;  < 0.001) versus nonexposure. In contrast, statins were associated with a greater risk of ICU admission (HR 1.133; 95% CI 1.065–1.205;  < 0.001) but lower risk of death (HR 0.626; 95% CI 0.565–0.694;  < 0.001).

Conclusion

This large, real‐world study suggests that for some contraindicated medications, including statins, longer‐term mortality benefits are likely to outweigh short‐term risks of exacerbating MG.

LETTER TO THE EDITOR

Response to the Comment by Steinkirchner et al. On the Article “Variation in Repeated Handgrip Strength Testing Indicates Submaximal Force Production in Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome”

LETTER TO THE EDITOR

Conduction Block Detection in Dysimmune Neuropathy: Hypothetical Pathophysiological ‘Truth’ Versus Clinical Pragmatism

LETTER TO THE EDITOR

Comment on “Variation in Repeated Handgrip Strength Testing Indicates Submaximal Force Production in Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome”