Correct combination
Case 106
【Discussion】There are a number of neural routes and nuclei in medulla oblongata. These routes are crossing and connecting with spinal cord, thalamus, cerebellum and cerebrum. Then, axial sliced images of medulla oblongata are not the same. However, neural routes at the medial portions of medulla oblongata are limited. In short, from the ventral (anterior) side to the dorsal side, pyramidal tract, medial lemniscus, medial longitudinal fasciculus and hypoglossal nucleus and its nerve exist in line.
Pyramidal decussation (crossing) is found at the lowest portion of medulla oblongata. Then, the damage of pyramidal route usually induces contralateral hemi-lateral paresis. In our case, MRI showed small acute infarction at left-sided medial medulla oblongata and medical findings revealed right-sided hemiparesis, indicating disorder of the left pyramidal tract at the upper portion than pyramidal decussation.
Medial lemniscus bundles include deep sensory routes of gracilis fasciculus and cuneatus fasciculus from spinal cord. Gracilis fasciculus is in charge of sensory neuron from lower body (Th7 or lower) and cuneatus fasciculus, in charge of sensory neuron from upper body (Th6 or higher except face). Gracilis fasciculus and cuneatus fasciculus cross to contra-lateral side just upper than the pyramidal decussation. Then, the damages of medial lemniscus cause contralateral deep sensory disorder. In our case, MRI showed small acute infarction at left-sided medial medulla oblongata and medical findings revealed right-sided hemi-numbness, indicating disorder of medial lemniscus at upper portion compared to crossing of gracilis and cuneatus fasciculi.
Medial longitudinal fasciculus connects orbit cranial nerves in brain stem: oculomotor nerve (III), trochlear nerve (IV) and abducens nerve (VI). Further, medial longitudinal fasciculus connects to vestibulocochlear nerve (VIII) and cervical spinal cord. Medial longitudinal fasciculus functions coordinate eye movement, especially horizontal gaze movement. For example, when the thing moves horizontally, eye ball moves horizontally following the thing with neck moving. Medial longitudinal fasciculus play a male role for horizontal eye gazing and neck moving. When medial longitudinal fasciculus is damaged, horizontal gazing disorder occurs. In our case, MRI showed small acute infarction at left-sided medial medulla oblongata and medical findings revealed horizontal nystagmus, indicating disorder of medial longitudinal fasciculus.
Hypoglossal nucleus situates at the internal and most dorsal side. Hypoglossal nerve from its nucleus runs outside of the internal lemniscus and pyramidal tract. When hypoglossal nucleus and/or nerve is damaged, the tip of tongue deviated to the disturbed side. In our case, MRI showed small acute infarction at left-sided medial and ventral-sided medulla (not dorsal-sided) oblongata and medical findings revealed no tongue deviation, indicating no evidence of disturbance of hypoglossal nucleus and nerve.
The medial medullary oblongata gets blood supply from paramedial branches from anterior spinal artery which comes from posterior inferior cerebellar artery (PICA). The occlusion of paramedial branches, anterior spinal artery or PICA causes the ischemic change of medial medullary oblongata.
【Summary】
We present a sixty five-year-old male suffering from right hemi-lateral numbness and dizziness. Medical findings revealed hypertension, slight right motor hemiparesis, deep sensory (touch sensation) disorder and horizontal nystagmus. Brain MRI showed acute infarction at ventral and medial portion of medullary oblongata. Based on MRI and medical findings, neural damages of pyramidal tract, medial lemniscus and medial longitudinal fasciculus. We should keep in mind that from ventral portion to ventral dorsal portion of medullary oblongata, there are pyramidal tract, medial lemniscus, medial longitudinal medial fasciculus and hypoglossal nucleus in line. The damages cause contralateral hemiparesis, contralateral numbness, disturb-sided horizontal gaze disorder (horizontal nystagmus) and disturb-sided tongue tip deviation, respectively, although our case did not have disorder of hypoglossal nerve palsy simply because no damage of the most dorsal side medullary oblongata.
【References】
The content of this article is written by the book as below.
Peter Duus. Neuroloigisch-topische Diagnostik: Anatomie Physiologie Klinik, second edition translated in Japanese by Hajime Handa and Junya Hanakita. Bunkodo, Tokyo
2018.5.30