Download ALS - AJNR Blog

Amyotrophic Lateral
Sclerosis
Ali Nasim MD
Fellow, 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 Findings
Symptoms:
•Upper motor - Babinski, spasticity,
hyperreflexia.
•Lower motor - asymmetric muscle weakness,
atrophy, fasciculations
•Bulbar signs - dysphagia, slurred speech
ALS: Clinical Findings
Types:
•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
Neurology criteria:
• Evidence of LMN degeneration by clinical,
electrophysiological, or neuropathological 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
Stone
Stephen Hawking
Jon
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