The clinical and radiological profile of primary lateral sclerosis: a population-based study

The French national protocol for Kennedy's disease (SBMA): consensus diagnostic and management recommendations

Background

Kennedy’s disease (KD), also known as spinal and bulbar muscular atrophy (SBMA), is a rare, adult-onset, X-linked recessive neuromuscular disease caused by CAG expansions in exon 1 of the androgen receptor gene (AR). The objective of the French national diagnostic and management protocol is to provide evidence-based best practice recommendations and outline an optimised care pathway for patients with KD, based on a systematic literature review and consensus multidisciplinary observations.

Results

The initial evaluation, confirmation of the diagnosis, and management should ideally take place in a tertiary referral centre for motor neuron diseases, and involve an experienced multidisciplinary team of neurologists, endocrinologists, cardiologists and allied healthcare professionals. The diagnosis should be suspected in an adult male presenting with slowly progressive lower motor neuron symptoms, typically affecting the lower limbs at onset. Bulbar involvement (dysarthria and dysphagia) is often a later manifestation of the disease. Gynecomastia is not a constant feature, but is suggestive of a suspected diagnosis, which is further supported by electromyography showing diffuse motor neuron involvement often with asymptomatic sensory changes. A suspected diagnosis is confirmed by genetic testing. The multidisciplinary assessment should ascertain extra-neurological involvement such as cardiac repolarisation abnormalities (Brugada syndrome), signs of androgen resistance, genitourinary abnormalities, endocrine and metabolic changes (glucose intolerance, hyperlipidemia). In the absence of effective disease modifying therapies, the mainstay of management is symptomatic support using rehabilitation strategies (physiotherapy and speech therapy). Nutritional evaluation by an expert dietician is essential, and enteral nutrition (gastrostomy) may be required. Respiratory management centres on the detection and treatment of bronchial obstructions, as well as screening for aspiration pneumonia (chest physiotherapy, drainage, positioning, breath stacking, mechanical insufflation-exsufflation, cough assist machnie, antibiotics). Non-invasive mechanical ventilation is seldom needed. Symptomatic pharmaceutical therapy includes pain management, endocrine and metabolic interventions. There is no evidence for androgen substitution therapy.

Conclusion

The French national Kennedy’s disease protocol provides management recommendations for patients with KD. In a low-incidence condition, sharing and integrating regional expertise, multidisciplinary experience and defining consensus best-practice recommendations is particularly important. Well-coordinated collaborative efforts will ultimately pave the way to the development of evidence-based international guidelines.

Primary lateral sclerosis: consensus diagnostic criteria

Primary lateral sclerosis (PLS) is a neurodegenerative disorder of the adult motor system. Characterised by a slowly progressive upper motor neuron syndrome, the diagnosis is clinical, after exclusion of structural, neurodegenerative and metabolic mimics. Differentiation of PLS from upper motor neuron-predominant forms of amyotrophic lateral sclerosis remains a significant challenge in the early symptomatic phase of both disorders, with ongoing debate as to whether they form a clinical and histopathological continuum. Current diagnostic criteria for PLS may be a barrier to therapeutic development, requiring long delays between symptom onset and formal diagnosis. While new technologies sensitive to both upper and lower motor neuron involvement may ultimately resolve controversies in the diagnosis of PLS, we present updated consensus diagnostic criteria with the aim of reducing diagnostic delay, optimising therapeutic trial design and catalysing the development of disease-modifying therapy.

Progressive brainstem pathology in motor neuron diseases: Imaging data from amyotrophic lateral sclerosis and primary lateral sclerosis

A standardised, single-centre, longitudinal imaging protocol was used to evaluate longitudinal brainstem alterations in 100 patients with amyotrophic lateral sclerosis (ALS) with reference to 33 patients with primary lateral sclerosis (PLS), 30 patients with frontotemporal dementia (FTD) and 100 healthy controls. “Brainstem pathology in amyotrophic lateral sclerosis and primary lateral sclerosis: A longitudinal neuroimaging study” [1] ALS patients were scanned twice; 4 months apart. T1-weighted imaging data were acquired on a 3 T Philips Achieva MRI system, using a 3D Inversion Recovery prepared Spoiled Gradient Recalled echo (IR-SPGR) sequence. Raw MRI data underwent meticulous quality control before pre-processing. A Bayesian segmentation algorithm was utilised to parcellate the brainstem into the medulla oblongata, pons and mesencephalon before estimating the volume of each segment. Vertex-based shape analyses were carried out to characterise anatomical patterns of atrophy. Brainstem volume loss in ALS was dominated by medulla oblongata atrophy, but significant pontine pathology was also detected. Brainstem volume reductions were more significant in PLS than in ALS after correcting for demographic variables and total intracranial volume. Shape analyses revealed bilateral ‘flattening’ of the medullary pyramids in ALS compared to healthy controls. Our data demonstrate that computational neuroimaging readily detects brainstem pathology in vivo in both amyotrophic lateral sclerosis and primary lateral sclerosis.

Thalamic, hippocampal and basal ganglia pathology in primary lateral sclerosis and amyotrophic lateral sclerosis: Evidence from quantitative imaging data

Primary lateral sclerosis and amyotrophic lateral sclerosis are primarily associated with motor cortex and corticospinal tract pathology. A standardised, prospective, single-centre neuroimaging protocol was used to characterise thalamic, hippocampal and basal ganglia involvement in 33 patients with primary lateral sclerosis (PLS), 100 patients with amyotrophic lateral sclerosis (ALS), and 117 healthy controls. “Widespread subcortical grey matter degeneration in primary lateral sclerosis: a multimodal imaging study with genetic profiling” [1] Imaging data were acquired on a 3 T MRI system using a 3D Inversion Recovery prepared Spoiled Gradient Recalled echo sequence. Model based segmentation was used to estimate the volumes of the thalamus, hippocampus, amygdala, caudate, pallidum, putamen and accumbens nucleus in each hemisphere. The hippocampus was further parcellated into cytologically-defined subfields. Total intracranial volume (TIV) was estimated for each participant to aid the interpretation of subcortical volume alterations. Group comparisons were corrected for age, gender, TIV, education and symptom duration. Considerable thalamic, hippocampal and accumbens nucleus atrophy was detected in PLS compared to healthy controls and selective dentate, molecular layer, CA1, CA3, and CA4 hippocampal pathology was also identified. In ALS, additional volume reductions were noted in the amygdala, left caudate and the hippocampal-amygdala transition area of the hippocampus. Our imaging data provide evidence of extensive and phenotype-specific patterns of subcortical degeneration in PLS.

Widespread subcortical grey matter degeneration in primary lateral sclerosis: a multimodal imaging study with genetic profiling

BACKGROUND

Primary lateral sclerosis (PLS) is a low incidence motor neuron disease which carries a markedly better prognosis than amyotrophic lateral sclerosis (ALS). Despite sporadic reports of extra-motor symptoms, PLS is widely regarded as a pure upper motor neuron disorder. The post mortem literature of PLS is strikingly sparse and very little is known of subcortical grey matter pathology in this condition.

METHODS

A prospective imaging study was undertaken with 33 PLS patients, 117 healthy controls and 100 ALS patients to specifically assess the integrity of subcortical grey matter structures and determine whether PLS and ALS have divergent thalamic, hippocampal and basal ganglia signatures. Volumetric, morphometric, segmentation and vertex-wise analyses were carried out in the three study groups to evaluate the integrity of thalamus, hippocampus, caudate, amygdala, pallidum, putamen and accumbens nucleus in each hemisphere. The hippocampus was further parcellated to characterise the involvement of specific subfields.

RESULTS

Considerable thalamic, caudate, and hippocampal atrophy was detected in PLS based on both volumetric and vertex analyses. Significant volume reductions were also detected in the accumbens nuclei. Hippocampal atrophy in PLS was dominated by dentate gyrus, hippocampal tail and CA4 subfield volume reductions. The morphometric comparison of ALS and PLS cohorts revealed preferential medial bi-thalamic pathology in PLS compared to the predominant putaminal degeneration detected in ALS. Another distinguishing feature between ALS and PLS was the preferential atrophy of the amygdala in ALS.

CONCLUSIONS

PLS is associated with considerable subcortical grey matter degeneration and due to the extensive extra-motor involvement, it should no longer be regarded a pure upper motor neuron disorder. Given its unique pathological features and a clinical course which differs considerably from ALS, dedicated research studies and disease-specific therapeutic strategies are urgently required in PLS.

Brainstem pathology in amyotrophic lateral sclerosis and primary lateral sclerosis: A longitudinal neuroimaging study

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Computational neuroimaging captures focal brainstem pathology in motor neuron diseases in contrast to both healthy- and disease controls.

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ALS patients exhibit progressive medulla oblongata, pontine and mesencephalic volume loss over time.

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Brainstem atrophy in ALS and PLS is dominated by medulla oblongata volume reductions.

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Vertex analyses of ALS patients reveal flattening of the medullary pyramids bilaterally.

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Morphometric analyses in ALS detect density reductions in the mesencephalic crura consistent with corticospinal tract degeneration.

Background

Brainstem pathology is a hallmark feature of ALS, yet most imaging studies focus on cortical grey matter alterations and internal capsule white matter pathology. Brainstem imaging in ALS provides a unique opportunity to appraise descending motor tract degeneration and bulbar lower motor neuron involvement.

Methods

A prospective longitudinal imaging study has been undertaken with 100 patients with ALS, 33 patients with PLS, 30 patients with FTD and 100 healthy controls. Volumetric, vertex and morphometric analyses were conducted correcting for demographic factors to characterise disease-specific patterns of brainstem pathology. Using a Bayesian segmentation algorithm, the brainstem was segmented into the medulla, pons and mesencephalon to measure regional volume reductions, shape analyses were performed to ascertain the atrophy profile of each study group and region-of-interest morphometry was used to evaluate focal density alterations.

Results

ALS and PLS patients exhibit considerable brainstem atrophy compared to both disease- and healthy controls. Volume reductions in ALS and PLS are dominated by medulla oblongata pathology, but pontine atrophy can also be detected. In ALS, vertex analyses confirm the flattening of the medullary pyramids bilaterally in comparison to healthy controls and widespread pontine shape deformations in contrast to PLS. The ALS cohort exhibit bilateral density reductions in the mesencephalic crura in contrast to healthy controls, central pontine atrophy compared to disease controls, peri-aqueduct mesencephalic and posterior pontine changes in comparison to PLS patients.

Conclus

ions: Computational brainstem imaging captures the degeneration of both white and grey matter components in ALS. Our longitudinal data indicate progressive brainstem atrophy over time, underlining the biomarker potential of quantitative brainstem measures in ALS. At a time when a multitude of clinical trials are underway worldwide, there is an unprecedented need for accurate biomarkers to monitor disease progression and detect response to therapy. Brainstem imaging is a promising addition to candidate biomarkers of ALS and PLS.