Structural magnetic resonance imaging findings and histopathological correlations in motor neuron diseases—A systematic review and meta-analysis

OBJECTIVES The lack of systematic evidence on neuroimaging findings in motor neuron diseases (MND) hampers the diagnostic utility of magnetic resonance imaging (MRI). Thus, we aimed at performing a systematic review and meta-analysis of MRI features in MND including their histopathological correlation. METHODS In a comprehensive literature search, out of 5941 unique publications, 223 records assessing brain and spinal cord MRI findings in MND were eligible for a qualitative synthesis. 21 records were included in a random effect model meta-analysis. RESULTS Our meta-analysis shows that both T2-hyperintensities along the corticospinal tracts (CST) and motor cortex T2$^{*}$-hypointensitites, also called "motor band sign", are more prevalent in ALS patients compared to controls [OR 2.21 (95%-CI: 1.40-3.49) and 10.85 (95%-CI: 3.74-31.44), respectively]. These two imaging findings correlate to focal axonal degeneration/myelin pallor or glial iron deposition on histopathology, respectively. Additionally, certain clinical MND phenotypes such as amyotrophic lateral sclerosis (ALS) seem to present with distinct CNS atrophy patterns. CONCLUSIONS Although CST T2-hyperintensities and the "motor band sign" are non-specific imaging features, they can be leveraged for diagnostic workup of suspected MND cases, together with certain brain atrophy patterns. Collectively, this study provides high-grade evidence for the usefulness of MRI in the diagnostic workup of suspected MND cases. SYSTEMATIC REVIEW REGISTRATION https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42020182682

Radiological studies of LMNB1-related autosomal dominant leukodystrophy and Marinesco-Sjögren syndrome

There are approximately 6000 to 8000 rare diseases, each with a prevalence of less than 1 / 10 000, but in aggregate affecting 6 to 8% of the population. It is important to evaluate disease development and progression to know the natural course of any disease. This information can be utilized in diagnostics and in assessing effects of therapeutic interventions as they become available. This thesis describes the natural clinical history and evolution of imaging findings of two rare diseases over approximately two decades. Papers I, II and III present clinical, magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS) and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) findings in LMNB1-related autosomal dominant leukodystrophy (ADLD). MRI was found to be very sensitive in finding pathology in patients with LMNB1-related ADLD, even before the onset of clinical symptoms. However, even patients with widespread MRI changes can have a relatively mild symptomatology and present only slight disturbances in metabolic examinations such as MRS and FDG-PET. This is compatible with relatively intact axons, even as myelin impairment is widespread. Paper IV presents clinical and MRI findings in the brain and musculature in SIL1-positive Marinesco-Sjögren syndrome (MSS), and describes a new, mild phenotype of the disease with no intellectual disabilities and only slight motor disabilities. With a 19-year-long radiological follow-up, a slow progressive atrophic process in the cerebellum and brainstem could be demonstrated. MRI of the musculature shows early involvement of the quadriceps and gastrocnemii but not the tibialis anterior, progressing to widespread atrophy in the back and upper and lower limbs at the age of 20 years. In the mildest phenotype, the most severely affected muscles were the m gluteus maximus, m sartorius, m peroneus longus, and the lateral head of the m gastrocnemius

LMNB1-related autosomal-dominant leukodystrophy : Clinical and radiological course

OBJECTIVE: Duplication of the LMNB1 gene encoding lamin B1 causes adult-onset autosomal-dominant leukodystrophy (ADLD) starting with autonomic symptoms, which are followed by pyramidal signs and ataxia. Magnetic resonance imaging (MRI) of the brain reveals characteristic findings. This is the first longitudinal study on this disease. Our objective is to describe the natural clinical and radiological course of LMNB1-related ADLD. METHODS: Twenty-three subjects in two families with LMNB1 duplications were studied over two decades with clinical assessment and MRI of the brain and spinal cord. They were 29 to 70 years old at their first MRI. Repeated MRIs were performed in 14 subjects over a time period of up to 17 years. RESULTS: Pathological MRI findings were found in the brain and spinal cord in all examinations (i.e., even preceding clinical symptoms). MRI changes and clinical symptoms progressed in a definite order. Autonomic dysfunction appeared in the fifth to sixth decade, preceding or together with gait and coordination difficulties. Motor signs developed ascending from spastic paraplegia to tetraplegia and pseudobulbar palsy in the seventh decade. There were clinical, radiological, and neurophysiological signs of myelopathy. Survival lasted more than two decades after clinical onset. INTERPRETATION: LMNB1-related ADLD is a slowly progressive neurological disease. MRI abnormalities of the brain and spinal cord can precede clinical symptoms by more than a decade and are extensive in all symptomatic patients. Spinal cord involvement is a likely contributing factor to early autonomic symptoms and spastic paraplegia. Ann Neurol 2015;78:412-425.Atle Melberg och Raili Raininko delar sistaförfattarskapet.</p

LMNB1-related autosomal-dominant leukodystrophy : Clinical and radiological course

OBJECTIVE: Duplication of the LMNB1 gene encoding lamin B1 causes adult-onset autosomal-dominant leukodystrophy (ADLD) starting with autonomic symptoms, which are followed by pyramidal signs and ataxia. Magnetic resonance imaging (MRI) of the brain reveals characteristic findings. This is the first longitudinal study on this disease. Our objective is to describe the natural clinical and radiological course of LMNB1-related ADLD. METHODS: Twenty-three subjects in two families with LMNB1 duplications were studied over two decades with clinical assessment and MRI of the brain and spinal cord. They were 29 to 70 years old at their first MRI. Repeated MRIs were performed in 14 subjects over a time period of up to 17 years. RESULTS: Pathological MRI findings were found in the brain and spinal cord in all examinations (i.e., even preceding clinical symptoms). MRI changes and clinical symptoms progressed in a definite order. Autonomic dysfunction appeared in the fifth to sixth decade, preceding or together with gait and coordination difficulties. Motor signs developed ascending from spastic paraplegia to tetraplegia and pseudobulbar palsy in the seventh decade. There were clinical, radiological, and neurophysiological signs of myelopathy. Survival lasted more than two decades after clinical onset. INTERPRETATION: LMNB1-related ADLD is a slowly progressive neurological disease. MRI abnormalities of the brain and spinal cord can precede clinical symptoms by more than a decade and are extensive in all symptomatic patients. Spinal cord involvement is a likely contributing factor to early autonomic symptoms and spastic paraplegia. Ann Neurol 2015;78:412-425.Atle Melberg och Raili Raininko delar sistaförfattarskapet.</p

Glucose metabolism in the brain in LMNB1-related autosomal dominant leukodystrophy.

OBJECTIVE: LMNB1-related autosomal dominant leukodystrophy is caused by an overexpression of the protein lamin B1, usually due to a duplication of the LMNB1 gene. Symptoms start in 5th to 6th decade. This slowly progressive disease terminates with death. We studied brain glucose metabolism in this disease using 18 F-fluorodeoxyglucose positron emission tomography (PET). METHODS: We examined 8 patients, aged 48-64 years, in varying stages of clinical symptomatology. Two patients were investigated with quantitative PET on clinical indications after which six more patients were recruited. Absolute glucose metabolism was analyzed with the PVElab software in 6 patients and 18 healthy controls. A semiquantitative analysis using the CortexID software was performed in seven investigations, relating local metabolism levels to global glucose metabolism. RESULTS: The clinical quantitative PET revealed low global glucose metabolism, with the most marked reduction in the cerebellum. In the PVElab analysis, patients presented low mean glucose metabolism in the cerebellum, brainstem and global grey matter. In the semiquantitative analysis, 2 patients showed a decreased metabolism in the cerebellum and 4 patients a relatively higher metabolism in parts of the temporal lobes. Since none of the patients showed an increased metabolism in the quantitative analysis, we interpret these increases as "pseudo-increases" related to a globally reduced metabolism. CONCLUSIONS: Global reduction of grey matter glucose metabolism in this white matter disease most likely depends on a combination of cortical afferent dysfunction and, in later stages, neuronal loss. The lowest metabolism in the cerebellum is consistent with histopathological findings and prominent cerebellar symptoms