amyotrophic lateral sclerosis ali nasim md fellow, neuroradiology division at unc
TRANSCRIPT
Amyotrophic Lateral Sclerosis
Ali Nasim MDFellow, Neuroradiology Division at UNC
What is ALS?•A-myo-trophic = no-muscle-nourishment
•Lateral Sclerosis refers to involvement of the lateral corticospinal tracts.
•ALS is a degeneration of somatic motor neurons extending from upper motor cortical pyramidal neurons to lower motor neurons of the brainstem and cord.
History of ALS
• 1869 - First described in publication by Dr. Jean-Martin Charcot, in Paris.
• 1881 - Lectures translated into English
ALS: Clinical FindingsSymptoms:
•Upper motor - Babinski, spasticity, hyperreflexia.
•Lower motor - asymmetric muscle weakness, atrophy, fasciculations
•Bulbar signs - dysphagia, slurred speech
ALS: Clinical FindingsTypes:
•Classic - UMN and LMN
•Only UMN or only LMN
•Predominantly bulbar form - worse prognosis
•Familial - 15-20%
• 5600 cases per year in the US, 40-70 y/o, M:F 2:1
ALS: Clinical Findings• Progresses distal to proximal, with complete disability within 10 yrs
• 20% of patients survive >5 yrs
•Familial and juvenile onset survive 20-30 yrs after diagnosis
ALS: Clinical Findings• Revised El Escorial World Federation of Revised El Escorial World Federation of Neurology criteria:Neurology criteria:
• Evidence of LMN degeneration by clinical, Evidence of LMN degeneration by clinical, electrophysiological, or neuropathological electrophysiological, or neuropathological examination examination
• Evidence of UMN degeneration by clinical examination
• Progressive spread of symptoms or signs within a region or to other regions (The body is divided into four regions: cranial, cervical, thoracic and lumbosacral)
• Absence of electrophysiological, pathological or neuroimaging evidence of other disease processes.
ALS: Imaging Findings•Can have normal imaging
•Focal atrophy in chronic cases
• T2/FLAIR hyperintensity extending along the corticospinal tract from corona radiata to the brainstem
• Contrast enhancement - ?
•Deposition of iron in affected cortex
ALS: Imaging Findings
Early unilateral (left) ALS involvement in a patient with associated callosal agenesis.
ALS: Imaging Findings
Curved MPR: Corticospinal Tract extension
ALS: Imaging Findings
Enhancement is atypical but occasionally seen.
ALS: Imaging Findings
Bilateral high T2 signal in corticospinal tracts.
ALS: Imaging Findings
Increased iron (low T2 signal) deposition in the gray matter of the peri-Rolandic regions which underlying high signal in the white matte and dilatation of the adjacent cortical sulci.
ALS: Imaging Findings
FLAIR images shows high signal in the cortico-spinal tracts due to Wallerian degeneration.
ALS: Imaging Findings
•MR Spectroscopy:
• Decreased NAA/Cr ratio
• Increased choline and myoinositol
• Decreased glutamate in the precentral gyrus and peri-rolandi white matter
ALS: Pathology
• Loss of cortical pyramidal motor neurons and gliosis
• Corticospinal tracts with variable patterns of degeneration
• Precentral gyrus atrophy
ALS: Pathophyiology
• Cause of Spontaneous ALS unknown
• Single gene mutations can lead to selective motor neuron loss
• Glutamate excitotoxicity (etiology unknown)
ALS: Pathophyiology
Familial ALS:
• Copper/Zinc Superoxide dismutase (SOD1)gene mutation found to be associated with 20% of familial ALS
• Gain of function mutation
ALS: Interesting Info
• Reports of populations with increased incidence, most notably the Chamarro people of Guam (ALS-PCD)
• Incidence ranging 140-400 cases / 100,000 (nml 0.5-2 cases/ 100,00)
• Recent theory is that this was due to bat consumption and exposure to BMMA excitotoxins.
ALS: Notable People Affected
Lou Gehrig Stephen Hawking Jon Stone
ALS: Treatment
•Riluzole - glutamate release inhibitor
-Has been shown to increase NAA/Cr ratio
•Symptom treatment - ventilation, anti-spastic medications
References
• Kalra, S. et al, Neuroimaging in Amyotrophic Lateral Sclerosis. ALS and Other Motor Neuron Disorders. 2003:4 243-248.
• Kalra, S. et al, Gabapentin Therapy for Amyotrophic Lateral Sclerosis: Lack of Improvement in Neuronal Integrity Shown by MR Spectroscopy AJNR, Mar 2003; 24: 476 - 480.
• Bowen, B. , MR Imaging and Localized Proton Spectroscopy of the Precentral Gyrus in Amyotrophic Lateral Sclerosis AJNR, Apr 2000; 21: 647 - 658.
• statDx.com
• archives.org
• athiestnexus.org
• sabine.k12.la.us
• muppet.wikia.com