myelin is the target in Guillain-Barré syndrome (GBS), also called acute
inflammatory demyelinating polyneuropathy or Landry’s ascending paraly-
sis. GBS is an inflammatory disorder of the PNS characterized by rapid
onset of weakness and, often, paralysis of the legs, arms, respiratory mus-
cles, and muscles of facial expression.
137.The answer is b.(Kasper, pp 139–141. Young, p 376. Junqueira, pp
163, 165–166.)The region shown in the photomicrograph is the cerebel-
lum. An acute childhood infection in the cerebellum (cerebellitis) would
result in ataxia: inability to coordinate voluntary muscle movements,
unsteady movements, and staggering gait. Ataxia may be classified as axial
(trunk) or limb ataxia. In the sitting position, the child’s trunk may move
side to side and/or back to front and then resume a vertical position in a
jerky motion. Nystagmus (jerky eye movements) may also occur. Limb
ataxia manifests itself with loss of fine motor control of the hands or legs
and appears as though the person is able to coordinate his or her move-
ments. For example, a hand may sway back and forth when reaching for an
object. Most often, the cerebellar ataxia that follows a viral infection sub-
sides without treatment over a period of weeks to months. Occasionally, a
child will be left with a persistent movement disorder or behavioral prob-
lem. Amnesia (answer a)would result from a cortical injury; reflexive
actions(answer c)would occur at the level of the ventral horn cells in the
spinal cord; loss of pain sensation is complex and could involve the dorsal
root or trigeminal ganglion, the sensory and frontal cortex, limbic system,
and thalamus, but not the cerebellar cortex (answer d);and total or partial
loss of ability to use or understand language, aphasia (answer e),would
be the result of a cortical injury. Damage to the pararhinal–entorhinal–
hippocampal–mammillary body–thalamus circuit, the fornix, or the tem-
poral lobe can cause amnesia. There are different types of memory. For
example, working memory can be affected by prefrontal lesions or by
lesions to specific temperoparietal regions subserving the modality being
used. Aphasia can involve several different areas of the cortex including the
frontal, parietal, and/or temporal lobes.
Note the three layers forming the cerebellar cortex (molecular layer at
left/top, the large Purkinje cell layer, and the granular layer). The mnemonic
MPG: Molecular, Purkinje, and Granular may help you remember the lay-
ers. White matter is inside of the three layers of gray matter. Basket cells,
Purkinje cells, and granule cells compose the cerebellar cortex. Basket cells
242 Anatomy, Histology, and Cell Biology