[What's behind cerebellar dizziness? - News on diagnosis and therapy]

Vertigo and dizziness comprise a multisensory and multidisciplinary syndrome of different etiologies. The term "cerebellar vertigo and dizziness" comprises a heterogenous group of disorders with clinical signs of cerebellar dysfunction and is caused by vestibulo-cerebellar, vestibulo-spinal or cerebellar systems. About 10 % of patients in an outpatient clinic for vertigo and balance disorders suffer from cerebellar vertigo and dizziness. According to the course of the symptoms, one can considers 3 types: permanent complaints, recurrent episodes of vertigo and balance disorders, or an acute onset of complaints. The most common diagnoses in patients with cerebellar vertigo and dizziness were as follows: degenerative disease, hereditary forms and acquired forms. In a subgroup of patients with cerebellar vertigo, central cerebellar oculomotor dysfunction is indeed the only clinical correlate of the described symptoms. 81 % of patients with cerebellar vertigo suffer from permanent, persistent vertigo and dizziness, 31 % from vertigo attacks, and 21 % from both. Typical clinical cerebellar signs, including gait and limb ataxia or dysarthria, were found less frequently. Key to diagnosis is a focused history as well as a thorough clinical examination with particular attention to oculomotor function. Regarding oculomotor examination, the most common findings were saccadic smooth pursuit, gaze-evoked nystagmus, provocation nystagmus, rebound nystagmus, central fixation nystagmus, most commonly downbeat nystagmus, and disturbances of saccades. Thus, oculomotor examination is very sensitive in diagnosing cerebellar vertigo and dizziness, but not specific in distinguishing different etiologies. Laboratory examinations using posturography and a standardized gait analysis can support the diagnosis, but also help to estimate the risk of falls and to quantify the course and possible symptomatic treatment effects. Patients with cerebellar vertigo and dizziness should receive multimodal treatment.

Amantadine for NeuroenhaNcement in acutE patients Study - a protocol for a prospective pilot proof of concept phase IIb study in intensive and intermediate care unit patients (ANNES)

BACKGROUND

Persisting coma is a common complication in (neuro)intensive care in neurological disease such as acute ischemic stroke, intracerebral hemorrhage or subarachnoid hemorrhage. Amantadine acts as a nicotinic receptor antagonist, dopamine receptor agonist and non-competitive N-Methyl-D-aspartate receptor antagonist. Amantadine is a long-known drug, originally approved for treatment of influenza A and Parkinson`s Disease. It has been proven effective in improving vigilance after traumatic brain injury. The underlying mechanisms remain largely unknown, albeit anti-glutamatergic and dopaminergic effects might be most relevant. With limited evidence of amantadine efficacy in non-traumatic pathologies, the aim of our study is to assess the effects of amantadine for neuroenhancement in non-traumatic neurointensive patients with persisting coma.

METHODS

An investigator-initiated, monocenter, phase IIb proof of concept open-label pilot study will be carried out. Based on the Simon design, 43 adult (neuro)intensive care patients who meet the clinical criteria of persisting coma not otherwise explained and < 8 points on the Glasgow Coma Scale (GCS) will be recruited. Amantadine will be administered intravenously for five days at a dosage of 100 mg bid. The primary endpoint is an improvement of at least 3 points on the GCS. If participants present as non-responders (increase < 3 points or decrease on the GCS) within the first 48 h, the dosage will be doubled from day three to five. Secondary objectives aim to demonstrate that amantadine improves vigilance via alternative scales. Furthermore, the incidence of adverse events will be investigated and electroencephalography (EEG) will be recorded at baseline and end of treatment.

DISCUSSION

The results of our study will help to systematically assess the clinical utility of amantadine for treatment of persisting coma in non-traumatic brain injury. We expect that, in the face of only moderate treatment risk, a relevant number of patients will benefit from amantadine medication by improved vigilance (GCS increase of at least 3 points) finally leading to a better rehabilitation potential and improved functional neurological outcome. Further, the EEG data will allow evaluation of brain network states in relation to vigilance and potentially outcome prediction in this study cohort.

TRIAL REGISTRATION

NCT05479032.

Dysfunctional neuro-muscular mechanisms explain gradual gait changes in prodromal spastic paraplegia

BACKGROUND

In Hereditary Spastic Paraplegia (HSP) type 4 (SPG4) a length-dependent axonal degeneration in the cortico-spinal tract leads to progressing symptoms of hyperreflexia, muscle weakness, and spasticity of lower extremities. Even before the manifestation of spastic gait, in the prodromal phase, axonal degeneration leads to subtle gait changes. These gait changes - depicted by digital gait recording - are related to disease severity in prodromal and early-to-moderate manifest SPG4 participants.

METHODS

We hypothesize that dysfunctional neuro-muscular mechanisms such as hyperreflexia and muscle weakness explain these disease severity-related gait changes of prodromal and early-to-moderate manifest SPG4 participants. We test our hypothesis in computer simulation with a neuro-muscular model of human walking. We introduce neuro-muscular dysfunction by gradually increasing sensory-motor reflex sensitivity based on increased velocity feedback and gradually increasing muscle weakness by reducing maximum isometric force.

RESULTS

By increasing hyperreflexia of plantarflexor and dorsiflexor muscles, we found gradual muscular and kinematic changes in neuro-musculoskeletal simulations that are comparable to subtle gait changes found in prodromal SPG4 participants.

CONCLUSIONS

Predicting kinematic changes of prodromal and early-to-moderate manifest SPG4 participants by gradual alterations of sensory-motor reflex sensitivity allows us to link gait as a directly accessible performance marker to emerging neuro-muscular changes for early therapeutic interventions.

The prodromal phase of hereditary spastic paraplegia type 4: the preSPG4 cohort study

This cohort study aimed to characterize the prodromal phase of hereditary spastic paraplegia type 4 (SPG4) using biomarkers and clinical signs and symptoms that develop before manifest gait abnormalities. Fifty-six first-degree relatives at risk of developing SPG4 underwent blinded genotyping and standardized phenotyping, including the Spastic Paraplegia Rating Scale (SPRS), complicating symptoms, non-motor affection, Three-Minute Walk, and neurophysiological assessment. Automated MR image analysis was used to compare volumetric properties. CSF of 33 probands was analysed for neurofilament light chain (NfL), tau, and amyloid-β (Aβ). Thirty participants turned out to be SPAST mutation carriers, whereas 26 did not inherit a SPAST mutation. Increased reflexes, ankle clonus, and hip abduction weakness were more frequent in prodromal mutation carriers but were also observed in non-mutation carriers. Only Babinski's sign differentiated reliably between the two groups. Timed walk and non-motor symptoms did not differ between groups. Whereas most mutation carriers had total SPRS scores of 2 points or more, only two non-mutation carriers reached more than 1 point. Motor evoked potentials revealed no differences between mutation and non-mutation carriers. We found NfL but not tau or Aβ to rise in CSF of mutation carriers when approaching the time point of predicted disease manifestation. Serum NfL did not differ between groups. Volumetric MRI analyses did not reveal group differences apart from a smaller cingulate gyrus in mutation carriers. This study depicts subtle clinical signs which develop before gait abnormalities in SPG4. Long-term follow-up is needed to study the evolution of SPG4 in the prodromal stage and conversion into manifest disease. NfL in CSF is a promising fluid biomarker that may indicate disease activity in prodromal SPG4 but needs further evaluation in longitudinal studies.

Specific Gait Changes in Prodromal Hereditary Spastic Paraplegia Type 4: preSPG4 Study

BACKGROUND

In hereditary spastic paraplegia type 4 (SPG4), subclinical gait changes might occur years before patients realize gait disturbances. The prodromal phase of neurodegenerative disease is of particular interest to halt disease progression by future interventions before impairment has manifested.

OBJECTIVE

The objective of this study was to identify specific movement abnormalities before the manifestation of gait impairment and quantify disease progression in the prodromal phase.

METHODS

Seventy subjects participated in gait assessment, including 30 prodromal SPAST pathogenic variant carriers, 17 patients with mild-to-moderate manifest SPG4, and 23 healthy control subjects. An infrared-camera-based motion capture system assessed gait to analyze features such as range of motion and continuous angle trajectories. Those features were correlated with disease severity as assessed by the Spastic Paraplegia Rating Scale, neurofilament light chain as a fluid biomarker indicating neurodegeneration, and motor-evoked potentials.

RESULTS

Compared with healthy control subjects, we found an altered gait pattern in prodromal pathogenic variant carriers during the swing phase in the segmental angle of the foot (Dunn's post hoc test, q = 3.1) and heel ground clearance (q = 2.8). Furthermore, range of motion of segmental angle was reduced for the foot (q = 3.3). These changes occurred in prodromal pathogenic variant carriers without quantified leg spasticity in clinical examination. Gait features correlated with neurofilament light chain levels, central motor conduction times of motor-evoked potentials, and Spastic Paraplegia Rating Scale score.

CONCLUSIONS

Gait analysis can quantify changes in prodromal and mild-to-moderate manifest SPG4 patients. Thus, gait features constitute promising motor biomarkers characterizing the subclinical progression of spastic gait and might help to evaluate interventions in early disease stages. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Detection of spinal long fiber tract degeneration in HSP: Improved diffusion tensor imaging

Spinal diffusion tensor imaging (sDTI) is still a challenging technique for selectively evaluating anatomical areas like the pyramidal tracts (PT), dorsal columns (DC), and anterior horns (AH) in clinical routine and for reliably quantifying white matter anisotropy and diffusivity. In neurodegenerative diseases, the value of sDTI is promising but not yet well understood. The objective of this prospective, single-center study was to evaluate the long fiber tract degeneration within the spinal cord in normal aging (n = 125) and to prove its applicability in pathologic conditions as in patients with molecular genetically confirmed hereditary spastic paraplegias (HSP; n = 40), a prototypical disease of the first motor neuron and in some genetic variants with affection of the dorsal columns. An optimized monopolar Stejskal-Tanner sequence for high-resolution, axial sDTI of the cervical spinal cord at 3.0 T with advanced standardized evaluation methods was developed for a robust DTI value estimation of PT, DC, and AH in both groups. After sDTI measurement at C2, an automatic motion correction and an advanced semi-automatic ROI-based, standardized evaluation of white matter anisotropy and diffusivity was performed to obtain regional diffusivity measures for PT, DC, and AH. Reliable and stable sDTI values were acquired in a healthy population without significant decline between age 20 and 65. Reference values for PT, DC, and AH for fractional anisotropy (FA), mean diffusivity (MD), and radial diffusivity (RD) were established. In HSP patients, the decline of the long spinal fiber tracts could be demonstrated by diffusivity abnormalities in the pyramidal tracts with significantly reduced PT_FA (p < 0.001), elevated PT_RD (p = 0.002) and reduced PT_MD (p = 0.003) compared to healthy controls. Furthermore, FA was significantly reduced in DC_FA (p < 0.001) with no differences in AH. In a genetically homogeneous subgroup of SPG4 patients (n = 12) with affection of the dorsal columns, DC_RD significantly correlated with the overall disease severity as measured by the Spastic Paraplegia Rating Scale (SPRS) (r = - 0.713, p = 0.009). With the most extensive sDTI study in vivo to date, we showed that axial sDTI combined with motion correction and advanced data post-processing strategies enables robust measurements and is ready to use, allowing recognition and quantification of disease- and age-related changes of the PT, DC, and AH. These results may also encourage the usage of sDTI in other neurodegenerative diseases with spinal cord involvement to explore its capability as selective biomarkers.

Characteristics of serum neurofilament light chain as a biomarker in hereditary spastic paraplegia type 4

Objective

While the anticipated rise of disease‐modifying therapies calls for reliable trial outcome parameters, fluid biomarkers are lacking in spastic paraplegia type 4 (SPG4), the most prevalent form of hereditary spastic paraplegia. We therefore investigated serum neurofilament light chain (sNfL) as a potential therapy response, diagnostic, monitoring, and prognostic biomarker in SPG4.

Methods: We assessed sNfL levels in 93 patients with SPG4 and 60 healthy controls. The longitudinal study of sNfL levels in SPG4 patients covered a baseline, 1‐year follow‐up and 2‐year follow‐up visit.

Results

Levels of sNfL were significantly increased in patients with genetically confirmed SPG4 compared to healthy controls matched in age and sex (p = 0.013, r = 0.2). Our cross‐sectional analysis revealed a greater difference in sNfL levels between patients and controls in younger ages with decreasing fold change of patient sNfL elevation at older ages. Over our observational period of 2 years, sNfL levels remained stable in SPG4 patients. Disease severity and progression did not correlate with sNfL levels.

Interpretation: Our longitudinal data indicate a stable turnover of sNfL in manifest SPG4; therefore, sNfL levels are not suitable to monitor disease progression in SPG4. However, sNfL may be valuable as a therapy response biomarker, since its turnover could be modified by interventions. As the course of sNfL levels appears to be most dynamic around the onset of SPG4, the ability to detect a therapy response appears to be especially promising in younger patients, matching the need to initiate treatment in early disease stages.

De Novo and Dominantly Inherited SPTAN1 Mutations Cause Spastic Paraplegia and Cerebellar Ataxia

BACKGROUND

Pathogenic variants in SPTAN1 have been linked to a remarkably broad phenotypical spectrum. Clinical presentations include epileptic syndromes, intellectual disability, and hereditary motor neuropathy.

OBJECTIVES

We investigated the role of SPTAN1 variants in rare neurological disorders such as ataxia and spastic paraplegia.

METHODS

We screened 10,000 NGS datasets across two international consortia and one local database, indicative of the level of international collaboration currently required to identify genes causative for rare disease. We performed in silico modeling of the identified SPTAN1 variants.

RESULTS

We describe 22 patients from 14 families with five novel SPTAN1 variants. Of six patients with cerebellar ataxia, four carry a de novo SPTAN1 variant and two show a sporadic inheritance. In this group, one variant (p.Lys2083del) is recurrent in four patients. Two patients have novel de novo missense mutations (p.Arg1098Cys, p.Arg1624Cys) associated with cerebellar ataxia, in one patient accompanied by intellectual disability and epilepsy. We furthermore report a recurrent missense mutation (p.Arg19Trp) in 15 patients with spastic paraplegia from seven families with a dominant inheritance pattern in four and a de novo origin in one case. One further patient carrying a de novo missense mutation (p.Gln2205Pro) has a complex spastic ataxic phenotype. Through protein modeling we show that mutated amino acids are located at crucial interlinking positions, interconnecting the three-helix bundle of a spectrin repeat.

CONCLUSIONS

We show that SPTAN1 is a relevant candidate gene for ataxia and spastic paraplegia. We suggest that for the mutations identified in this study, disruption of the interlinking of spectrin helices could be a key feature of the pathomechanism. © 2022 International Parkinson and Movement Disorder Society.

Chromium and cobalt intoxication mimicking mitochondriopathy

A 53-year old male with a history of progressive visual impairment, hearing loss, peripheral neuropathy, poorly controlled diabetes mellitus, cardiomyopathy, and weight loss was referred to the rare disease center due to the suspicion of mitochondrial cytopathy. In line with mitochondrial dysfunction, lactate in CSF was increased. Genetic testing by whole-exome sequencing and mitochondrial DNA did not reveal a likely cause. The case remained unsolved until he developed pain in his right hip, where he had received total hip arthroplasty 12 years earlier. An orthopedic evaluation revealed substantial shrinkage of the head of the hip prosthesis. Due to metal-on-metal wear, debris chromium and cobalt levels in serum were massively increased and significantly improved with multisystemic impairment after exchanging the defective implant.

Neurofilament light chain is a cerebrospinal fluid biomarker in hereditary spastic paraplegia

Objective

Despite the need for diagnostics and research, data on fluid biomarkers in hereditary spastic paraplegia (HSP) are scarce. We, therefore, explore Neurofilament light chain (NfL) levels in cerebrospinal fluid (CSF) of patients with hereditary spastic paraplegia and provide information on the influence of demographic factors.

Methods

The study recruited 59 HSP cases (33 genetically confirmed) and 59 controls matched in age and sex. Neurofilament light chain levels were assessed by enzyme‐linked immunosorbent assay. The statistical analysis included the effects of age, sex, and genetic status (confirmed vs. not confirmed).

Results

Levels of CSF NfL were significantly increased in patients with hereditary spastic paraplegia compared to controls (median 741 pg/mL vs. 387 pg/mL, p < 0.001). Age (1.4% annual increase) and male sex (81% increase) impacted CSF NfL levels in patients. The age‐dependent increase of CSF NfL levels was steeper in controls (2.6% annual increase). Thus, the CSF NfL ratio of patients and matched controls—expressing patients’ fold increases in CSF NfL—declined considerably with age.

Interpretation

CSF NfL is a reliable cross‐sectional biomarker in hereditary spastic paraplegia. Sex is a relevant factor to consider, as male patients have remarkably higher CSF NfL levels. While levels also increase with age, the gap between patients and controls is narrowing in older subjects. This indicates distinct temporal dynamics of CSF NfL in patients with hereditary spastic paraplegia, with a rise around phenotypic conversion and comparatively static levels afterward.

Cerebrospinal fluid findings in patients with psychotic symptoms-a retrospective analysis

In current international classification systems (ICD-10, DSM5), the diagnostic criteria for psychotic disorders (e.g. schizophrenia and schizoaffective disorder) are based on symptomatic descriptions since no unambiguous biomarkers are known to date. However, when underlying causes of psychotic symptoms, like inflammation, ischemia, or tumor affecting the neural tissue can be identified, a different classification is used ("psychotic disorder with delusions due to known physiological condition" (ICD-10: F06.2) or psychosis caused by medical factors (DSM5)). While CSF analysis still is considered optional in current diagnostic guidelines for psychotic disorders, CSF biomarkers could help to identify known physiological conditions. In this retrospective, partly descriptive analysis of 144 patients with psychotic symptoms and available CSF data, we analyzed CSF examinations' significance to differentiate patients with specific etiological factors (F06.2) from patients with schizophrenia, schizotypal, delusional, and other non-mood psychotic disorders (F2). In 40.3% of all patients, at least one CSF parameter was out of the reference range. Abnormal CSF-findings were found significantly more often in patients diagnosed with F06.2 (88.2%) as compared to patients diagnosed with F2 (23.8%, p < 0.00001). A total of 17 cases were identified as probably caused by specific etiological factors (F06.2), of which ten cases fulfilled the criteria for a probable autoimmune psychosis linked to the following autoantibodies: amphiphysin, CASPR2, CV2, LGl1, NMDA, zic4, and titin. Two cases presented with anti-thyroid tissue autoantibodies. In four cases, further probable causal factors were identified: COVID-19, a frontal intracranial tumor, multiple sclerosis (n = 2), and neurosyphilis. Twenty-one cases remained with "no reliable diagnostic classification". Age at onset of psychotic symptoms differed between patients diagnosed with F2 and F06.2 (p = 0.014), with the latter group being older (median: 44 vs. 28 years). Various CSF parameters were analyzed in an exploratory analysis, identifying pleocytosis and oligoclonal bands (OCBs) as discriminators (F06.2 vs. F2) with a high specificity of > 96% each. No group differences were found for gender, characteristics of psychotic symptoms, substance dependency, or family history. This study emphasizes the great importance of a detailed diagnostic workup in diagnosing psychotic disorders, including CSF analysis, to detect possible underlying pathologies and improve treatment decisions.

PolyQ-expanded ataxin-3 protein levels in peripheral blood mononuclear cells correlate with clinical parameters in SCA3: a pilot study

In view of upcoming clinical trials, quantitative molecular markers accessible in peripheral blood are of critical importance as prognostic or pharmacodynamic markers in genetic neurodegenerative diseases such as Spinocerebellar Ataxia Type 3 (SCA3), in particular for signaling target engagement. In this pilot study, we focused on the quantification of ataxin-3, the protein altered in SCA3, in human peripheral blood mononuclear cells (PBMCs) acquired from preataxic and ataxic SCA3 mutation carriers as well as healthy controls, as a molecular marker directly related to SCA3 pathophysiology. We established two different highly sensitive TR-FRET-based immunoassays to measure the protein levels of either total full-length, non-expanded and expanded, ataxin-3 or specifically polyQ-expanded ataxin-3. In PBMCs, a clear discrimination between SCA3 mutation carrier and controls were seen measuring polyQ-expanded ataxin-3 protein level. Additionally, polyQ-expanded ataxin-3 protein levels correlated with disease progression and clinical severity as assessed by the Scale for the Assessment and Rating of Ataxia. Total full-length ataxin-3 protein levels were directly influenced by the expression levels of the polyQ-expanded ataxin-3 protein, but were not correlated with clinical parameters. Assessment of ataxin-3 levels in fibroblasts or induced pluripotent stem cells allowed to distinguish mutation carriers from controls, thus providing proof-of-principle validation of our PBMC findings across cell lines. Total full-length or polyQ-expanded ataxin-3 protein was not detectable by TR-FRET assays in other biofluids like plasma or cerebrospinal fluid, indicating the need for ultra-sensitive assays for these biofluids. Standardization studies revealed that tube systems, blood sampling, and PBMC preparation may influence ataxin-3 protein levels indicating a high demand for standardized protocols in biomarker studies. In conclusion, the polyQ-expanded ataxin-3 protein is a promising candidate as a molecular target engagement marker in SCA3 in future clinical trials, determinable even in—easily accessible—peripheral blood biomaterials. These results, however, require validation in a larger cohort and further standardization of modifying conditions.

Defining diagnostic cutoffs in neurological patients for serum very long chain fatty acids (VLCFA) in genetically confirmed X-Adrenoleukodystrophy

X-linked Adrenoleukodystrophy (X-ALD) is caused by mutations in the ABCD1 gene resulting in the accumulation of very long chain fatty acids (VLCFA). X-ALD is the most common peroxisomal disorder with adult patients (male and female) presenting with progressive spastic paraparesis with bladder disturbance, sensory ataxia with impaired vibration sense, and leg pain. 80% of male X-ALD patients have an adrenal failure, while adrenal dysfunction is rare in women with X-ALD. The objective of this study was to define optimal serum VLCFA cutoff values in patients with X-ALD-like phenotypes for the differentiation of genetically confirmed X-ALD and Non-X-ALD individuals. Three groups were included into this study: a) X-ALD cases with confirmed ABCD1 mutations (n = 34) and two Non-X-ALD cohorts: b) Patients with abnormal serum VCLFA levels despite negative testing for ABCD1 mutations (n = 15) resulting from a total of 1,953 VLCFA tests c) Phenotypically matching patients as Non-X-ALD controls (n = 104). Receiver operating curve analysis was used to optimize VLCFA cutoff values, which differentiate patients with genetically confirmed X-ALD and Non-X-ALD individuals. The serum concentration of C26:0 was superior to C24:0 for the detection of X-ALD. The best differentiation of Non-X-ALD and X-ALD individuals was obtained with a cutoff value of < 1.0 for the C24:0/C22:0 ratio resulting in a sensitivity of 97%, a specificity of 94.1% and a positive predictive value (PPV) of 83.8% for true X-ALD. Our findings further suggested a cutoff of < 0.02 for the ratio C26:0/C22:0 leading to a sensitivity of 90.9%, a specificity of 95.0%, and a PPV of 80.6%. Pearson correlation indicated a significant positive association between total blood cholesterol and VLCFA values. Usage of serum VLCFA are economical and established biomarkers suitable for the guidance of genetic testing matching the X-ALD phenotype. We suggest using our new optimized cutoff values, especially the two ratios (C24:0/C22:0 and C26:0/C22:0), in combination with standard lipid profiles.

Face pareidolia in schizophrenia

BACKGROUND

Faces convey valuable daily life social signals. As in most psychiatric conditions, non-verbal social cognition or its components including face processing may be aberrant in schizophrenia (SZ). Social participation of individuals with SZ is vital for their quality of life, and remediation of social abilities in this population is of high relevance both for society and clinical care.

METHOD

Tuning to faces in non-face images such as shadows, grilled toasts, or ink blots is called face pareidolia. Humans possess high sensitivity to facial signals: even fetuses and infants are well tuned to coarse face cues. Here we assessed face tuning in individuals with SZ and person-by-person matched controls by using a new experimental tool, a set of food-plate images bordering on the Giuseppe Arcimboldo style. The key benefit of these images is that single components do not trigger face processing.

RESULTS AND CONCLUSIONS

The outcome indicates that individuals with SZ exhibit aberrant face tuning in face-like non-face images (χ²(1) = 17.44, p = 0.0001) that can hamper adaptive interaction with peers and social participation hindering, in turn, clinical remediation. Face response rate in SZ patients was related to the scores on the event arrangement task tapping social cognition (Pearson product-moment correlation, r = 0.602, p = 0.01) and on picture completion task assessing visual perceptual organization (Spearman's rho = 0.614, p = 0.009). Therefore, poor performance on the face tuning task is unlikely to be accounted for by deviant general cognitive abilities, but rather by impairments in perceptual integration and social cognition. Comparison of these findings with data in autism and other neuropsychiatric conditions provides novel insights on the origins of face tuning in SZ and triggers brain imaging research.

FAHN/SPG35: a narrow phenotypic spectrum across disease classifications

The endoplasmic reticulum enzyme fatty acid 2-hydroxylase (FA2H) plays a major role in the formation of 2-hydroxy glycosphingolipids, main components of myelin. FA2H deficiency in mice leads to severe central demyelination and axon loss. In humans it has been associated with phenotypes from the neurodegeneration with brain iron accumulation (fatty acid hydroxylase-associated neurodegeneration, FAHN), hereditary spastic paraplegia (HSP type SPG35) and leukodystrophy (leukodystrophy with spasticity and dystonia) spectrum. We performed an in-depth clinical and retrospective neurophysiological and imaging study in a cohort of 19 cases with biallelic FA2H mutations. FAHN/SPG35 manifests with early childhood onset predominantly lower limb spastic tetraparesis and truncal instability, dysarthria, dysphagia, cerebellar ataxia, and cognitive deficits, often accompanied by exotropia and movement disorders. The disease is rapidly progressive with loss of ambulation after a median of 7 years after disease onset and demonstrates little interindividual variability. The hair of FAHN/SPG35 patients shows a bristle-like appearance; scanning electron microscopy of patient hair shafts reveals deformities (longitudinal grooves) as well as plaque-like adhesions to the hair, likely caused by an abnormal sebum composition also described in a mouse model of FA2H deficiency. Characteristic imaging features of FAHN/SPG35 can be summarized by the 'WHAT' acronym: white matter changes, hypointensity of the globus pallidus, ponto-cerebellar atrophy, and thin corpus callosum. At least three of four imaging features are present in 85% of FA2H mutation carriers. Here, we report the first systematic, large cohort study in FAHN/SPG35 and determine the phenotypic spectrum, define the disease course and identify clinical and imaging biomarkers.

Nerve ultrasound characterizes AMN polyneuropathy as inhomogeneous and focal hypertrophic

Objective

High-resolution nerve ultrasound (HRUS) is a painless tool to quickly evaluate peripheral nerve morphology in vivo. This study set out to characterize peripheral nerve involvement in X-linked adrenomyeloneuropathy (AMN) by HRUS.

Methods

Thirteen adults with genetically proven AMN were examined using the Ultrasound pattern sum score (UPSS) to evaluate morphological abnormalities of peripheral nerves, vagal nerves, as well as cervical nerve roots. Ultrasound results were correlated with clinical findings and nerve conduction studies.

Results

UPSS was increased in six out of 13 patients. Nerve enlargement was mostly inhomogeneous and regional. The median, ulnar, and vagal nerves presented with more prominent alterations than nerves of the lower limbs. The proximal-to-distal ratio was significantly enlarged for the median nerve. HRUS findings matched nerve conduction studies, but identified one patient with enlarged nerves and yet normal conduction velocities. Sonographic findings did not correlate with disease duration or disease severity as assessed by the spastic paraplegia rating scale.

Conclusion

HRUS reveals significant multifocal regional nerve swellings with reduced echo intensity as the morphological equivalent of electrophysiological peripheral nerve affection in AMN patients. Ultrasound and NCS characteristics in AMN seem to differ from other demyelinating neuropathies like CIDP or CMT1a.

Trial registration

German clinical-trial-register (DRKS) (DRKS-ID 00005253) Registered 15 October 2013.

Electronic supplementary material

The online version of this article (10.1186/s13023-018-0939-7) contains supplementary material, which is available to authorized users.

Serum neurofilament light chain is increased in hereditary spastic paraplegias

Blood biomarkers are still largely missing in hereditary spastic paraplegias (HSPs). We here explored Neurofilament light chain (NfL) as a biomarker in HSP. Serum NfL was assessed in 96 HSP (63 genetically confirmed), 96 healthy control, and 33 ALS subjects by single molecule array (Simoa). Compared to controls, NfL was increased in HSP (P < 0.001), correlating with cross‐sectional disease progression (ρ = 0.28). Levels were lower than in ALS (P < 0.001), allowing to differentiate HSP from ALS (AUC = 0.91). Serum NfL might serve as a biomarker in HSP indicating neuronal damage and, if confirmed longitudinally, disease progression. It might also support differentiating HSP from ALS.

Nerve Ultrasound Predicts Treatment Response in Chronic Inflammatory Demyelinating Polyradiculoneuropathy-a Prospective Follow-Up

As reliable biomarkers of disease activity are lacking, monitoring of therapeutic response in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) remains a challenge. We sought to determine whether nerve ultrasound and electrophysiology scoring could close this gap. In CIDP patients (fulfilling EFNS/PNS criteria), we performed high-resolution nerve ultrasound to determine ultrasound pattern sum scores (UPSS) and predominant echotexture nerve conduction study scores (NCSS) as well as Medical Research Council sum scores (MRCSS) and inflammatory neuropathy cause and treatment disability scores (INCAT) at baseline and after 12 months of standard treatment. We retrospectively correlated ultrasound morphology with nerve histology when available. 72/80 CIDP patients featured multifocal nerve enlargement, and 35/80 were therapy-naïve. At baseline, clinical scores correlated with NCSS (r2 = 0.397 and r2 = 0.443, p < 0.01), but not or hardly with UPSS (Medical Research Council sum scores MRCSS r2 = 0.013, p = 0.332; inflammatory neuropathy cause and treatment disability scores INCAT r2 = 0.053, p = 0.048). Longitudinal changes in clinical scores, however, correlated significantly with changes in both UPSS and NCSS (r2 = 0.272-0.414, p < 0.0001). Combining nerve/fascicle size with echointensity and histology at baseline, we noted 3 distinct classes: 1) hypoechoic enlargement, reflecting active inflammation and onion bulbs; 2) nerve enlargement with additional hyperechogenic fascicles/perifascicular tissue in > 50% of measured segments, possibly reflecting axonal degeneration; and 3) almost no enlargement, reflecting "burned-out" or "cured" disease without active inflammation. Clinical improvement after 12 months was best in patients with pattern 1 (up to 75% vs up to 43% in pattern 2/3, Fisher's exact test p < 0.05). Nerve ultrasound has additional value not only for diagnosis, but also for classification of disease state and may predict treatment response.

Hereditary spastic paraplegia type 5: natural history, biomarkers and a randomized controlled trial

Spastic paraplegia type 5 (SPG5) is a rare subtype of hereditary spastic paraplegia, a highly heterogeneous group of neurodegenerative disorders defined by progressive neurodegeneration of the corticospinal tract motor neurons. SPG5 is caused by recessive mutations in the gene CYP7B1 encoding oxysterol-7α-hydroxylase. This enzyme is involved in the degradation of cholesterol into primary bile acids. CYP7B1 deficiency has been shown to lead to accumulation of neurotoxic oxysterols. In this multicentre study, we have performed detailed clinical and biochemical analysis in 34 genetically confirmed SPG5 cases from 28 families, studied dose-dependent neurotoxicity of oxysterols in human cortical neurons and performed a randomized placebo-controlled double blind interventional trial targeting oxysterol accumulation in serum of SPG5 patients. Clinically, SPG5 manifested in childhood or adolescence (median 13 years). Gait ataxia was a common feature. SPG5 patients lost the ability to walk independently after a median disease duration of 23 years and became wheelchair dependent after a median 33 years. The overall cross-sectional progression rate of 0.56 points on the Spastic Paraplegia Rating Scale per year was slightly lower than the longitudinal progression rate of 0.80 points per year. Biochemically, marked accumulation of CYP7B1 substrates including 27-hydroxycholesterol was confirmed in serum (n = 19) and cerebrospinal fluid (n = 17) of SPG5 patients. Moreover, 27-hydroxycholesterol levels in serum correlated with disease severity and disease duration. Oxysterols were found to impair metabolic activity and viability of human cortical neurons at concentrations found in SPG5 patients, indicating that elevated levels of oxysterols might be key pathogenic factors in SPG5. We thus performed a randomized placebo-controlled trial (EudraCT 2015-000978-35) with atorvastatin 40 mg/day for 9 weeks in 14 SPG5 patients with 27-hydroxycholesterol levels in serum as the primary outcome measure. Atorvastatin, but not placebo, reduced serum 27-hydroxycholesterol from 853 ng/ml [interquartile range (IQR) 683-1113] to 641 (IQR 507-694) (-31.5%, P = 0.001, Mann-Whitney U-test). Similarly, 25-hydroxycholesterol levels in serum were reduced. In cerebrospinal fluid 27-hydroxycholesterol was reduced by 8.4% but this did not significantly differ from placebo. As expected, no effects were seen on clinical outcome parameters in this short-term trial. In this study, we define the mutational and phenotypic spectrum of SPG5, examine the correlation of disease severity and progression with oxysterol concentrations, and demonstrate in a randomized controlled trial that atorvastatin treatment can effectively lower 27-hydroxycholesterol levels in serum of SPG5 patients. We thus demonstrate the first causal treatment strategy in hereditary spastic paraplegia.

Cognitive impairment in Glucocerebrosidase (GBA)-associated PD: Not primarily associated with cerebrospinal fluid Abeta and Tau profiles

BACKGROUND

A proportion of idiopathic Parkinson's disease patients (PD_idiopathic ) with dementia show altered CSF profiles of amyloid β (Aβ) and Tau. PD patients with Glucocerebrosidase (GBA) mutations (PD_GBA ) present with even more cognitive decline than seen in PD_idiopathic .

OBJECTIVE

The objective of this study was to evaluate whether CSF profiles of Aβ and tau are associated with the prominent cognitive impairment in PD_GBA .

METHODS

CSF levels of Aβ_1-42 , t-Tau, p-Tau, and total alpha-synuclein were assessed in 479 participants (50 PD_GBA , 308 PD_idiopathic , 121 healthy controls).

RESULTS

Older age was associated with cognitive impairment in PD_GBA and PD_idiopathic . Despite prominent cognitive impairment, PD_GBA showed similar CSF levels of Aβ_1-42 , t-Tau, and p-Tau as seen in healthy controls. In contrast, lower levels of Aβ_1-42 and higher levels of t-Tau and p-Tau were associated with worse cognitive performance in PD_idiopathic .

CONCLUSIONS

The prominent cognitive impairment in PD_GBA seems not primarily associated with Aβ and Tau profiles in CSF. © 2017 International Parkinson and Movement Disorder Society.

A look inside the nerve - Morphology of nerve fascicles in healthy controls and patients with polyneuropathy

OBJECTIVE

Polyneuropathies are increasingly analyzed by ultrasound. Summarizing, diffuse enlargement is typical in Charcot-Marie Tooth type 1 (CMT1a), regional enlargement occurs in inflammatory neuropathies. However, a distinction of subtypes is still challenging. Therefore, this study focused on fascicle size and pattern in controls and distinct neuropathies.

METHODS

Cross-sectional area (CSA) of the median, ulnar and peroneal nerve (MN, UN, PN) was measured at predefined landmarks in 50 healthy controls, 15 CMT1a and 13 MMN patients. Additionally, largest fascicle size and number of visible fascicles was obtained at the mid-upper arm cross-section of the MN and UN and in the popliteal fossa cross-section of the PN.

RESULTS

Cut-off normal values for fascicle size in the MN, UN and PN were defined (<4.8mm², <2.8mm² and <3.5mm²). In CMT1a CSA and fascicle values are significantly enlarged in all nerves, while in MMN CSA and fascicles are regionally enlarged with predominance in the upper arm nerves. The ratio of enlarged fascicles and all fascicles was significantly increased in CMT1a (>50%) in all nerves (p<0.0001), representing diffuse fascicle enlargement, and moderately increased in MMN (>20%), representing differential fascicle enlargement (enlarged and normal fascicles at the same location) sparing the peroneal nerve (regional fascicle enlargement). Based on these findings distinct fascicle patterns were defined.

CONCLUSION

Normal values for fascicle size could be evaluated; while CMT1a features diffuse fascicle enlargement, MMN shows regional and differential predominance with enlarged fascicles as single pathology.

SIGNIFICANCE

Pattern analysis of fascicles might facilitate distinction of several otherwise similar neuropathies.

Nerve ultrasound as follow-up tool in treated multifocal motor neuropathy

BACKGROUND AND PURPOSE

High-resolution ultrasound is a valuable tool in supporting the diagnosis of multifocal motor neuropathy (MMN) but longitudinal data under therapy are lacking.

METHODS

The change in peripheral nerve ultrasound pattern in patients with MMN was assessed over time. Patients with MMN received a thorough initial examination and follow-up over a period of 6-12 months using high-resolution ultrasound of the cervical roots and the nerves of the arms and legs, nerve conduction studies, Medical Research Council Sum Score (MRCSS) and Rotterdam Inflammatory Neuropathy Cause and Treatment Group (INCAT) score to evaluate changes under treatment. The Ultrasound Pattern Sum Score (UPSS) was used as standardized peripheral nerve ultrasound protocol.

RESULTS

Seventeen patients with MMN received initial examinations of whom 12 were successfully followed up. All patients with MMN showed at least localized but often multifocal peripheral nerve enlargement. An enlarged overall cross-sectional area as well as enlarged single fascicles (>3 mm²) in clinically and electrophysiologically affected (>90%) and unaffected (>70%) nerves were found. The UPSS did not correlate with clinical disability at both visits. However, the change in clinical disability (evaluated as difference in MRCSS) and the change in UPSS correlated significantly inversely (P = 0.004).

CONCLUSIONS

High-resolution sonography of peripheral nerves revealed multifocal nerve enlargement in MMN. Distinct enlargement patterns may support the diagnosis. Ultrasound findings did not correlate well with clinical severity or electrophysiological findings at initial presentation. As changes in UPSS correlated significantly with the clinical course in terms of muscle strength (MRCSS), sonographic assessment may represent a useful tool for therapeutic monitoring.

Hypomorphic mutations in POLR3A are a frequent cause of sporadic and recessive spastic ataxia

Despite extensive efforts, half of patients with rare movement disorders such as hereditary spastic paraplegias and cerebellar ataxias remain genetically unexplained, implicating novel genes and unrecognized mutations in known genes. Non-coding DNA variants are suspected to account for a substantial part of undiscovered causes of rare diseases. Here we identified mutations located deep in introns of POLR3A to be a frequent cause of hereditary spastic paraplegia and cerebellar ataxia. First, whole-exome sequencing findings in a recessive spastic ataxia family turned our attention to intronic variants in POLR3A, a gene previously associated with hypomyelinating leukodystrophy type 7. Next, we screened a cohort of hereditary spastic paraplegia and cerebellar ataxia cases (n = 618) for mutations in POLR3A and identified compound heterozygous POLR3A mutations in ∼3.1% of index cases. Interestingly, >80% of POLR3A mutation carriers presented the same deep-intronic mutation (c.1909+22G>A), which activates a cryptic splice site in a tissue and stage of development-specific manner and leads to a novel distinct and uniform phenotype. The phenotype is characterized by adolescent-onset progressive spastic ataxia with frequent occurrence of tremor, involvement of the central sensory tracts and dental problems (hypodontia, early onset of severe and aggressive periodontal disease). Instead of the typical hypomyelination magnetic resonance imaging pattern associated with classical POLR3A mutations, cases carrying c.1909+22G>A demonstrated hyperintensities along the superior cerebellar peduncles. These hyperintensities may represent the structural correlate to the cerebellar symptoms observed in these patients. The associated c.1909+22G>A variant was significantly enriched in 1139 cases with spastic ataxia-related phenotypes as compared to unrelated neurological and non-neurological phenotypes and healthy controls (P = 1.3 × 10-4). In this study we demonstrate that (i) autosomal-recessive mutations in POLR3A are a frequent cause of hereditary spastic ataxias, accounting for about 3% of hitherto genetically unclassified autosomal recessive and sporadic cases; and (ii) hypomyelination is frequently absent in POLR3A-related syndromes, especially when intronic mutations are present, and thus can no longer be considered as the unifying feature of POLR3A disease. Furthermore, our results demonstrate that substantial progress in revealing the causes of Mendelian diseases can be made by exploring the non-coding sequences of the human genome.

Uniparental disomy determined by whole-exome sequencing in a spectrum of rare motoneuron diseases and ataxias

Background

The genetic causes of many rare inherited motoneuron diseases and ataxias (MND and ATX) remain largely unresolved, especially for sporadic patients, despite tremendous advances in gene discovery. Whole exome data is often available for patients, but it is rarely evaluated for unusual inheritance patterns, such as uniparental disomy (UPD). UPD is the inheritance of two copies of a chromosomal region from one parent, which may generate homozygosity for a deleterious recessive variant from only one carrier‐parent. Detection of UPD‐caused homozygous disease‐causing variants is detrimental to accurate genetic counseling. Whole‐exome sequencing can allow for the detection of such events.

Methods

We systematically studied the exomes of a phenotypically heterogeneous cohort of unresolved cases (n = 96 families) to reveal UPD events hindering a diagnosis and to evaluate the prevalence of UPD in recessive MND and ATX.

Results

One hereditary spastic paraplegia case harbored homozygous regions spanning 80% of chromosome 16. A homozygous disease‐causing mutation in the SPG35 disease gene was then identified within this region.

Conclusion

This study demonstrates the ability to detect UPD in exome data of index patients. Our results suggest that UPD is a rare mechanism for recessive MND and ATX.

Ultrasound assessment of peripheral nerve pathology in neurofibromatosis type 1 and 2

OBJECTIVE

The neurofibromatoses (NF) type 1 and 2 are hereditary tumor predisposition syndromes caused by germline mutations in the NF1 and NF2 tumor suppressor genes. In NF1 and 2, peripheral nerve tumors occur regularly. For further characterizing nerve ultrasound was performed in patients with NF1 and 2.

METHODS

Patients with established diagnosis of NF1 (n=27) and NF2 (n=10) were included. Ultrasound of peripheral nerves and cervical roots was performed during routine follow-up visits. Healthy volunteers were studied for comparison.

RESULTS

In patients with NF1, median cross-sectional area (CSA) of most nerves was significantly increased compared to controls and to NF2 due to generalized plexiform tumors, which arose out of multiple fascicles in 23 of 27 patients (85%). These were often accompanied by cutaneous or subcutaneous neurofibromas. In NF2, the overall aspect of peripheral nerves consisted of localized schwannomas (80%) and, apart from that, normal nerve segments.

CONCLUSION

Nerve ultrasound is able to visualize different nerve pathologies in NF1 and NF2. It is a precise and inexpensive screening method for peripheral nerve manifestation in neurofibromatosis and should be considered as the first choice screening imaging modality for all peripheral nerves within reach of non-invasive ultrasound techniques.

SIGNIFICANCE

Ultrasound patterns of peripheral nerve pathologies are described for the first time in a large cohort of patients with NF1 and NF2. It is a suitable screening tool and enables targeted MRI analysis.

Peripheral nerve ultrasound scoring systems: benchmarking and comparative analysis

Ultrasound of the nerves is an additive diagnostic tool to evaluate polyneuropathy. Recently, the need for standardized scoring systems has widely been discussed; different scores are described so far. Therefore, 327 patients with polyneuropathy were analyzed by ultrasound in our laboratory. Consequently, several ultrasound scoring tools were applied, i.e., the nerve pattern classification according to Padua et al. in all patients with CIDP and variants, the Bochum ultrasound score (BUS) and the neuritis ultrasound protocol in immune-mediated neuritis, the ultrasound pattern sum score, the homogeneity score, and the nerve enlargement distribution score in all neuropathies if possible. For all scores good accuracy was found. Most patients with CIDP revealed hypoechoic enlarged nerves (Class 1), the BUS/NUP was useful to identify GBS (sensitivity >85%), MMN (100%) and CIDP (>70%), while the UPSS showed high sensitivity and positive/negative predictive values (N/PPV) in the diagnosis of GBS (>70%), CIDP (>85%) and axonal non-inflammatory neuropathies (>90%). Homogeneous nerves were found in most CMT1 patients (66.7%), while immune-mediated neuropathies mostly show regional nerve enlargement. The HS was suitable to identify CMT patients with an HS ≥5 points. All scores were easily applicable with high accuracy. The former-reported results could be similarly confirmed. However, all sores have some incompleteness concerning unselected polyneuropathy population, particularly rare and focal types. Scoring systems are useful and easily applicable. They show high accuracy in certain neuropathies, but also offer some gaps and can, therefore, only be used in addition to standard diagnostic routines such as electrophysiology.

Generation of induced pluripotent stem cells (iPSCs) from a hereditary spastic paraplegia patient carrying a homozygous Y275X mutation in CYP7B1 (SPG5)

Skin fibroblasts were obtained from a 47-year-old hereditary spastic paraplegia patient carrying a homozygous mutation Y275X in CYP7B1 (Cytochrome P450, Family 7, Subfamily B, Polypeptide 1), responsible for causing hereditary spastic paraplegia type 5 (SPG5). Induced pluripotent stem cells (iPSCs) were generated by transfection with episomal plasmids carrying hOCT4, hSOX2, hKLF4, hL-MYC and hLIN28. The generated line iPS-SPG5-Y275X was transgene-free, retained the specific mutation with no additional genomic aberrations, expressed pluripotency markers and was able to differentiate into cells of all germ layers in vitro. The generated iPS-SPG5-Y275X line may be a useful resource for disease modelling of SPG5.

Uniparental disomy of chromosome 16 unmasks recessive mutations of FA2H/SPG35 in 4 families

OBJECTIVE

Identifying an intriguing mechanism for unmasking recessive hereditary spastic paraplegias.

METHOD

Herein, we describe 4 novel homozygous FA2H mutations in 4 nonconsanguineous families detected by whole-exome sequencing or a targeted gene panel analysis providing high coverage of all known hereditary spastic paraplegia genes.

RESULTS

Segregation analysis revealed in all cases only one parent as a heterozygous mutation carrier whereas the other parent did not carry FA2H mutations. A macro deletion within FA2H, which could have caused a hemizygous genotype, was excluded by multiplex ligation-dependent probe amplification in all cases. Finally, a microsatellite array revealed uniparental disomy (UPD) in all 4 families leading to homozygous FA2H mutations. UPD was confirmed by microarray analyses and methylation profiling.

CONCLUSION

UPD has rarely been described as causative mechanism in neurodegenerative diseases. Of note, we identified this mode of inheritance in 4 families with the rare diagnosis of spastic paraplegia type 35 (SPG35). Since UPD seems to be a relevant factor in SPG35 and probably additional autosomal recessive diseases, we recommend segregation analysis especially in nonconsanguineous homozygous index cases to unravel UPD as mutational mechanism. This finding may bear major repercussion for genetic counseling, given the markedly reduced risk of recurrence for affected families.

GDF15/MIC1 and MMP9 Cerebrospinal Fluid Levels in Parkinson's Disease and Lewy Body Dementia

Based on animal and ex-vivo experiments, Growth/Differentiation Factor-15 (GDF15, also called Macrophage Inhibitory Cytokine-1, MIC1), a member of the transforming growth factor-beta family, and Matrix Metalloproteinase-9 (MMP9), a member of the matrix metalloprotease family may be potential markers for Lewy body disorders, i.e. Parkinson’s disease with (PDD) and without dementia (PDND) and Lewy body dementia (DLB). GDF15 has a prominent role in development, cell proliferation, differentiation, and repair, whereas MMP9 degrades, as a proteolytic enzyme, components of the extracellular matrix. In this study, cerebrospinal fluid GDF15 and MMP9 levels of 59 PDND, 17 PDD and 23 DLB patients, as well as of 95 controls were determined, and associated with demographic, clinical and biochemical parameters. Our analysis confirmed the already described association of GDF15 levels with age and gender. Corrected GDF15 levels were significantly higher in PDD than in PDND patients, and intermediate in DLB patients. Within Lewy body disorders, GDF15 levels correlated positively with age at onset of Parkinsonism and dementia, Hoehn & Yahr stage and cerebrospinal fluid t-Tau and p-Tau levels, and negatively with the Mini Mental State Examination. Remarkably, it does not relevantly correlate with disease duration. MMP9 was not relevantly associated with any of these parameters. Cerebrospinal GDF15, but not MMP9, may be a potential marker of and in Lewy body disorders.

In-vivo evidence that high mobility group box 1 exerts deleterious effects in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine model and Parkinson's disease which can be attenuated by glycyrrhizin

High-mobility group box 1 (HMGB1) is a nuclear and cytosolic protein that is released during tissue damage from immune and non-immune cells — including microglia and neurons. HMGB1 can contribute to progression of numerous chronic inflammatory and autoimmune diseases which is mediated in part by interaction with the receptor for advanced glycation endproducts (RAGE). There is increasing evidence from in vitro studies that HMGB1 may link the two main pathophysiological components of Parkinson's disease (PD), i.e. progressive dopaminergic degeneration and chronic neuroinflammation which underlie the mechanistic basis of PD progression.

Analysis of tissue and biofluid samples from PD patients, showed increased HMGB1 levels in human postmortem substantia nigra specimens as well as in the cerebrospinal fluid and serum of PD patients. In a mouse model of PD induced by sub-acute administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), systemic administration of neutralizing antibodies to HMGB1 partly inhibited the dopaminergic cell death, and reduced the increase of RAGE and tumour necrosis factor-alpha. The small natural molecule glycyrrhizin, a component from liquorice root which can directly bind to HMGB1, both suppressed MPTP-induced HMGB1 and RAGE upregulation while reducing MPTP-induced dopaminergic cell death in a dose dependent manner.

These results provide first in vivo evidence that HMGB1 serves as a powerful bridge between progressive dopaminergic neurodegeneration and chronic neuroinflammation in a model of PD, suggesting that HMGB1 is a suitable target for neuroprotective trials in PD.

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HMGB1 is up-regulated in Parkinson's disease.

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HMGB1 is translocalized into the cytoplasm after MPTP.

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Inhibition of HMGB1 protects against MPTP-toxicity.

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Translocalization of HMGB1 is reduced after inhibition a neutralizing antibody or glycyrrhizin.

Freezing of Swallowing

Background

Swallowing deficits and freezing phenomena represent severe parkinsonian features. Freezing as a symptom occurring during swallowing has not been reported on yet.

Methods

We report on 3 patients with probable PSP-parkinsonism (PSP-P) who manifested freezing of swallowing (FOS).

Results

All 3 patients experienced severe weight loss in recent months. At examination, 1 patient had freezing of gait. Video fluoroscopy showed nonfunctional trembling movements of the tongue and palate during chewing and volitional swallowing, with a 6- to 8-Hz frequency that is typical for freezing episodes during walking and finger tapping. These freezing episodes were accompanied by impaired oral bolus transportation. The pharyngeal phase was not relevantly affected.

Conclusions

FOS represents a novel disease feature of PSP-P. The feature may have fundamental, but potentially treatable, consequences for patients' health and quality of life and may be considered in patients with degenerative parkinsonism who experience severe and unexplained weight loss.