BALACLAVA HELMET DISTRIBUTION & Dejerine's onion-peel sensory loss?
(A) Divisional pattern of sensory loss (B) segmental pattern of sensory loss (C) schematic diagram of the trigeminal system in the brainstem The spinal trigeminal nucleus (STN) is the longest cranial nerve nucleus, extending caudally from the medulla to the upper cervical segment 4 of the spinal cord. Cytoarchitecturally, the STN is divided into three portions from rostral to caudal: Pars Oralis (from the Pons to the Hypoglossal nucleus/inferior olive) Pars Interpolaris (from the Hypoglossal nucleus/inferior olive to the obex ) Pars Caudalis (from the obex to C4) The STN has somatotopic arrangement, the central area of the face is represented by the rostral portion of the STN, and the more outer areas of the face are represented by the caudal portion of the STN. Therefore, lesions invading the subnucleus caudalis cause onion-skin pattern sensory impairment . The onion skin distribution differs from the dermatome distribution of the perip...
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