Imbalances can result tremors, jerks, dystonia, chorea and progressive motor weakness ending in diaphragmatic dysfunction, with the most common cause of mortality in most neurodegenerative disorders being aspiration pneumonia.Likewise, the globus pallidus is involved in the constant subtle regulation of movement that allows people to walk and engage in a wide variety of other activities with a minimal level of disruption.[9] (see primate basal ganglia#Pallidonigral set and pacemaker) The two parts receive successively a large quantity of GABAergic axonal terminal arborisations from the striatum through the dense striato-pallidonigral bundle.Infarction of the globus pallidus can be seen with anoxic brain injury, carbon monoxide poisoning and drug overdoses (MDMA and heroin), with the insult classically being bilateral.[10] Though damage to the globus pallidus can cause movement disorders, diseases like Parkinson's and essential tremor can paradoxically be treated by surgically inducing lesions in the nuclei using ultrasound, Gamma knife, or more rarely open surgery.The aim of these procedures is to reduce involuntary muscle tremors and improve extrapyramidal symptoms associated with neurodegeneration, though they can impact intellectual function and cause dysarthria.The link with the substantia nigra pars reticulata was stressed very early on due to the similarities in dendritic arborisation (and they are sometimes known as the pallidonigral set) but, in spite of strong evidence, this association remains controversial.
Overview of the main circuits of the basal ganglia. Globus pallidus externa and interna are shown in green. Picture shows 2 coronal slices that have been superimposed to include the involved basal ganglia structures, with + and – signs at the point of the arrows indicating, respectively, whether the pathway is excitatory or inhibitory in effect.
Green arrows
refer to excitatory
glutamatergic
pathways,
red arrows
refer to inhibitory
GABAergic
pathways and
turquoise arrows
refer to
dopaminergic
pathways that are excitatory on the direct pathway and inhibitory on the indirect pathway.