Massive hemispheric lesions. Brain stem lesions. Sympathetic pathways lie adjacent to spinothalamic tract throughout course. Cervical cord lesions such as syringomyelia, cord gliomas, ependymomas. Sympathetic chain injuries located in the neck or skull base.
Central lesions affect sweating over entire head, neck arms and upper trunk on same side.
Lesions in lower neck affect sweating over entire face. Lesions below the superior cervical ganglion may not affect sweating at all, as the main outflow to the facial blood vessels and sweat glands is below the superior-cervical ganglion.