Clinical diagnosis
Case 35
Brain stem composes of midbrain, pons, and medulla oblongata. Brain stem is filled with systematic neurofibers and neurotracts. The relation between brain stem and neurofiber looks complicated but neurotracts are arranged in good order. Midbrain connects with superior cellebellar peduncle, pons connects with middle cerebellar peduncle and medulla oblongata connects with inferior cellebellar peduncle. Further, midbrain owns oculomoter nerve nucleus (III) and trochlear nerve nucleus (IV), pons owns trigeminal nerve nucleus (V), abduct nerve nucleus (VI) and facial nerve nucleus (VII) and medulla oblongata owns vestibulocochlear nerve nucleus (VIII), glossopharyngeal nerve nucleus (IX), vagus nerve nucleus (X), accessory nerve nucleus (XI) and hypoglossal nerve nucleus (XII). Furthermore, brain stem contains pyramidal tract and extrapyramidal tract. It is well known that pyramidal crossing exists in medulla oblongata. The disorder of IX, X, XI and/or XII causes initially dysarthria and dysphagia.
In regards with arterial blood supply, brain stem is largely supplied by vertebral artery system. Midbrain, the upper part of brain stem is supplied with small branches of posterior cerebral artery and superior cerebellar artery. Pons, the middle of brain stem get blood supply from small branches of basilar artery which two vertebral artery fused. Medulla oblongata, the lower part of brain stem get blood supply from small branches of anterior inferior cerebellar artery (AICA) derived from basilar artery, posterior inferior cerebellar artery (PICA) derived from vertebral artery, and anterior spinal artery derived from vertebral artery.
In Case 1 with diplopia and swinging, fresh infarction of midbrain was found at cerebral crus level on DWI (Fig. 1). Disorders of cerebral crus and oculo-moter nerve nucleus on the upper medial portion of midbrain are considered to cause these symptoms. In Case 2 with left hemiparesis and ataxia, fresh infarction was found in midbrain at superior cerebellar peduncle level on DWI (Fig. 2). The anterior right hemi-lateral portion of midbrain at this level was where pyramidal tract and cerebellar tract exist.
In Case 3 with left hemiparesis and swallowing disturbance, fresh infarction was found to be traversed longitudinally in pons at middle cerebellar peduncle level on DWI (Fig. 3). In this level, pyramidal tract, sensory (tectospinal) tract and abduct nerve nucleus exist.
In Case 4 with right hemi-numbness, fresh infarction was found at the left lateral aspect of medulla oblongata. When the dorsal-lateral portion of medulla oblongata is damaged by occlusive disease of posterior inferior cerebellar artery, it is known that Wallenberg syndrome occurrs: nystagmus, nausea, vomiting, speech disturbance (dysarthria, dyshonia), hiccup. In our case, the pure Wallenburg syndrome was not present because the damage was localized in the lateral portion where lateral spinal-thalamic tract exist, inducing contralateral numbness and loss of temperature sensation.
【Summary】
We present four cases with fresh brain stem infarctions: two cases, midbrain; one case, pons: one case, medulla oblongata. Brain stem includes pyramidal tract, extra-pyramidal tract, sensory tract, brain nerve nucleus and cerebellar tract. Midbrain owns III and IV brain nerve nucleus plus superior cerebellar tract, Pons owns V, VI, VII brain nerve nucleus plus middle cerebellar tract, and medulla oblongata owns VIII, IX, X, XI XII brain nerve nucleus plus inferior cerebellar tract. As arterial blood supply, midbrain was supplied by small branches of posterior cerebral artery and superior cerebral artery, pons was supplied by small branches of basilar artery and medulla oblongata was supplied by small branches of anterior inferior cerebellar artery and posterior inferior cerebellar artery. We should keep in mind that the nerve circuit and arterial perfusion system of brain stem are arranged quite systematically.
【References】
Peter Duus. Neuroloigisch-topische Diagnostik: Anatomie Physiologie Klinik, second edition translated in Japanese by Hajime Handa and Junya Hanakita. Bunkodo, Tokyo
2016.12.7
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