Reduced isotope uptake restricted to the motor area in patients with amyotrophic lateral sclerosis

Neuroimaging to investigate multisystem involvement and provide biomarkers in amyotrophic lateral sclerosis

Neuroimaging allows investigating the extent of neurological systems degeneration in amyotrophic lateral sclerosis (ALS). Advanced MRI methods can detect changes related to the degeneration of upper motor neurons but have also demonstrated the participation of other systems such as the sensory system or basal ganglia, demonstrating in vivo that ALS is a multisystem disorder. Structural and functional imaging also allows studying dysfunction of brain areas associated with cognitive signs. From a biomarker perspective, numerous studies using diffusion tensor imaging showed a decrease of fractional anisotropy in the intracranial portion of the corticospinal tract but its diagnostic value at the individual level remains limited. A multiparametric approach will be required to use MRI in the diagnostic workup of ALS. A promising avenue is the new methodological developments of spinal cord imaging that has the advantage to investigate the two motor system components that are involved in ALS, that is, the lower and upper motor neuron. For all neuroimaging modalities, due to the intrinsic heterogeneity of ALS, larger pooled banks of images with standardized image acquisition and analysis procedures are needed. In this paper, we will review the main findings obtained with MRI, PET, SPECT, and nuclear magnetic resonance spectroscopy in ALS.

Brain perfusion imaging in amyotrophic lateral sclerosis: extent of cortical changes according to the severity and topography of motor impairment

In amyotrophic lateral sclerosis (ALS), attempts have been made to correlate the extent of cortical lesions with the intensity of motor dysfunction in ALS patients. Our aim was to compare the cerebral perfusion as measured by SPECT with the topography and severity of motor impairment as measured by ALSFRS. Fifty-five patients with sporadic ALS were included. 99mTc-ECD brain perfusion tomographic studies were performed and reconstructed slices analysed with a voxel-based statistical method (Statistical Parametric Mapping). Correlations between ALSFRS total score and sub-scores were calculated. We observed a positive correlation between the degree of involvement of the motor functions as measured by the ALSFRS score and the perfusion decrease of the cerebral cortex. Analysis of the ALSFRS sub-scores revealed that the cortical involvement was important for lower limbs score, moderate for bulbar score and below the level of statistical significance for the respiratory and upper limb scores. The decrease of perfusion was asymmetrical (right hemisphere) and observed mainly in the lateral premotor cortex, the insula and the cingulate cortex. Our study confirms that in ALS the cortical involvement is asymmetrical and predominant in the premotor region and the insula.

Cooperation of the basal ganglia, cerebellum, sensory cerebrum and hippocampus: possible implications for cognition, consciousness, intelligence and creativity

It is suggested that the anatomical structures which mediate consciousness evolved as decisive embellishments to a (non-conscious) design strategy present even in the simplest unicellular organisms. Consciousness is thus not the pinnacle of a hierarchy whose base is the primitive reflex, because reflexes require a nervous system, which the single-celled creature does not possess. By postulating that consciousness is intimately connected to self-paced probing of the environment, also prominent in prokaryotic behavior, one can make mammalian neuroanatomy amenable to dramatically straightforward rationalization. Muscular contraction is the nervous system's only externally directed product, and the signaling routes which pass through the various brain components must ultimately converge on the motor areas. The function of several components is still debatable, so it might seem premature to analyze the global operation of the circuit these routes constitute. But such analysis produces a remarkably simple picture, and it sheds new light on the roles of the individual components. The underlying principle is conditionally permitted movement, some components being able to veto muscular contraction by denying the motor areas sufficient activation. This is true of the basal ganglia (BG) and the cerebellum (Cb), which act in tandem with the sensory cerebrum, and which can prevent the latter's signals to the motor areas from exceeding the threshold for overt movement. It is also true of the anterior cingulate, which appears to play a major role in directing attention. In mammals, the result can be mere thought, provided that a second lower threshold is exceeded. The veto functions of the BG and the Cb stem from inhibition, but the countermanding disinhibition develops at markedly different rates in those two key components. It develops rapidly in the BG, control being exercised by the amygdala, which itself is governed by various other brain regions. It develops over time in the Cb, thereby permitting previously executed movements that have proved advantageous. If cognition is linked to overt or covert movement, intelligence becomes the ability to consolidate individual motor elements into more complex patterns, and creativity is the outcome of a race-to-threshold process which centers on the motor areas. Amongst the ramifications of these ideas are aspects of cortical oscillations, phantom limb sensations, amyotrophic lateral sclerosis (ALS) the difficulty of self-tickling and mirror neurons.

Review neuroimaging in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a chronic degenerative disorder of unknown etiology affecting the motor system. Conventional and non-conventional neuroimaging techniques can provide essential help both to increase the confidence in ALS diagnosis and to assess the disease evolution. Signal abnormalities at the level of the motor cortex and the corticospinal tract on conventional T2-weighted magnetic resonance (MR) images are a potentially useful marker of ALS pathology. However, the prognostic value of these conventional MR abnormalities is still hampered by their low pathological specificity. Non-conventional MR techniques with a higher pathological specificity, such as MR spectroscopy, magnetization transfer imaging and diffusion-weighted imaging, seem to have some potential not only for ALS diagnosis, but also for monitoring disease evolution either naturally or when modified by experimental treatments.

Biological markers in the diagnosis and treatment of ALS

The care of patients with amyotrophic lateral sclerosis (ALS), which has classically focused on treatment of symptomatology, has now entered an encouraging new era of therapy targeted at the pathophysiology of the disease. However, an objective measure of disease progression and therapeutic response is sorely needed. Quantitative neuromuscular examinations, measurement of pulmonary function, disability scales, and even survival, are limited by variability due to a number of poorly controlled factors. Quantitative electromyography, positron emission tomography scanning, and magnetic cortical stimulation, provide potential objective indicators of disease progression, but require a large number of patients and a long observation period for adequate statistical power. We have examined the role of magnetic resonance spectroscopic imaging in detecting acute changes in motor cortical metabolism in response to riluzole therapy. N-acetylaspartate (NAA), the most prominent signal in proton spectra of normal brain, is a neuron-specific molecule. ALS patients were found to experience a significant increase in the NAA/creatine ratio within 3 weeks of initiation of riluzole therapy. As glutamate can trigger the generation of reactive oxygen species in neurons, we speculate that acute changes in NAA levels may reflect oxidative injury to mitochondria where NAA is synthesised. The advent of a useful test for upper motor neuron metabolic compromise may provide an objective, non-invasive, short duration measure with which to screen the efficacy of potential therapeutic agents for ALS.

[Amyotrophic lateral sclerosis and herpes virus. Report of an unusual case: a cause or casual association?]

OBJECTIVE

To present a curious case of amyotrophic lateral sclerosis (ALS).

CASE

A forty-seven year old man claimed of paresis in the arms since four years. The electrical study of the muscles and nerves diagnosis was ALS, type Vulpian-Bernardt. The cerebrospinal fluid study revealed an inflammatory process and the positivity of immulogical reactions for Herpes simplex I. The blood-brain barrier study showed the possibility that immunological response for Herpes simplex I was produced in the spinal fluid space. A magnetic resonance suggested cystic myelopathy of cervical spinal cord expanding from C2 to C4. The patient received endovenous acyclovir for 21 days. Until two months after the medication we did not submit the patient to other subsidiary examinations.

DISCUSSION

Until now there is no specific drug treatment for ALS. The notion that there is a "syndrome of ALS" related with various causes may help to treat some patients.

Serial MRI and SPECT in amyotrophic lateral sclerosis: a case report

We report the case of a 42 year-old woman with amyotrophic lateral sclerosis (ALS). Neurological examination showed spastic paraparesis and muscular atrophy of the upper extremities. Increased signal intensity areas were present in the lateral corticospinal tract of the brain and cervical spinal cord on a T2-weighted image. Decreased signal intensity of the motor cortex on the T2-weighted image appeared during the course of the illness. SPECT showed hypoperfusion confined to the motor cortex. The area of increased signal intensity in the cervical spinal cord on the T2-weighted MR images extended to the anterolateral columns of the spinal cord. The area of hypoperfusion in SPECT extended to the fronto-parietal area with the progression of the disease. These changes in the MRI and SPECT findings may reflect progressive degeneration of the upper motor neurons in ALS.