Damaged lobe
Case 129
【Progress】She was given warfarin and received rehabilitation. Twenty days later, her dysfunction of upper extremity improved to 4/5 from 1/5.
【Discussion】
It is important to distinct occipital lobe from parietal lobe and temporal lobe. The occipital lobe is bordered from parietal lobe by occipitoparietal sinus which is clearly shown on the sagittal midline image of MRI. Occipital lobe composes of five gyrus: cuneus, lingula, superior occipital, middle occipital and inferior occipital. Of these, cuneus gyrus and lingula gyrus are present in the medial side of occipital lobe, which is divided by calcarine sulcus. Superior, middle and inferior occipital gyrus are situated in the lateral side of the occipital lobe.
Visual information emerged from retina is relayed to lateral geniculate body via optic chiasm and reach to the primary visual cortex. The same information from lateral geniculate body is relayed to superior colliculi and then, pulvinar and finally cerebral cortex.
Cuneus gyrus and lingula gyrus are the primary visual cortex (Brodmann area 17), reflecting the image of the retina. Namely, the lower visual field is projected to the cuneus gyrus, and the upper visual field is projected to the lingula gyrus. Further, the left visual field is projected to the right cuneus and lingula gyrus and the vice versa. Superior, middle and inferior occipital gyrus are the association visual cortex (Brodmann area 18, 19) which connect to superior colliculus and pulvinar of the thalamus. The upper area of the occipital lobe connects to the parietal lobe and functions determination of ‘where is it ?’ such as motion and existence sensitive. Meanwhile, the lower area of the occipital lobe connects to temporal lobe and limbic system related to memory and functions determination of ‘what is it ?’ such as color and/or object recognition, and ability to focus on motor actions in response to the outside stimuli. In other words, the lower area including lingula gyrus is involved in the perception and recognition of face and topography. Further, the lower area is considered to play a role in dreaming.
Superior colliculus which obtain auditory information from inferior colliculus and visual information from lateral geniculate body, is considered to function being orient ourselves in the moving world. Pulvinar connected from superior colliculus to the cerebral cortex is considered to play a role of forming the visual attention networks including social cognition and blindsight. It may be related to the visual manifestations of Lewy body disease.
In our case, I misread that the lesion with high signal intensity on DWI was found in the occipital lobe but it difinitely belongs to the temporal lobe because there exists cerebellum and occipital lobe, probable cuneus or superior occipital gyrus in Figs. 1B, 2, indicating attributed to the occlusion of left middle cerebral artery.
【Summary】
We present an eighty two-year-old female who suddenly suffered from right upper extremity paresis (1/5) and received brain MRI which showed a lesion with high signal intensity, indicating acute cerebral infarction. The infarction was first mis-read at the occipital lobe and it was correctly at the lobe of the temporal lobe. It is borne in mind that occipital lobe composes of five gyrus: cuneus, lingula, superior occipital, middle occipital and inferior occipital and calcarine sulcus divides between cuneatus gyrus and lingula gyrus where are the primary visual cortex (Lingula and cuneus). Conscious visual circuit includes retina, optic chiasm, lateral geniculate body and primary cortex and association area (superior, middle and inferior occipital gyrus). The upper area of the occipital lobe functions ‘where or how is it ?’ such as motion and existence sensitive. The lower area of the occipital lobe functions ‘what is it ?’ such as color and/or object recognition and related to dreaming.
Meanwhile, unconscious visual circuit includes lateral geniculate body, superior colliculus and pulvinar. Superior colliculus functions being orient ourselves in the moving world. Pulvinar plays a role of forming the visual attention networks including social cognition and blindsight. It may be related to the visual manifestations of Lewy body disease.
【References】
This article was written based on the documents of the book below and Wikipedia through internet.
Peter Duus. Neuroloigisch-topische Diagnostik: Anatomie Physiologie Klinik, second edition translated in Japanese by Hajime Handa and Junya Hanakita. Bunkodo, Tokyo
2018.11.14