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| Medial medullary syndrome Classification and external resources |
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| ICD-10 | G46.3 |
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Medial medullary syndrome, also known as inferior alternating syndrome, hyploglossal alternating hemiplegia, or lower alternating hemiplegia,[1] is a set of clinical features resulting from an infarct in the anterior spinal artery, which supplies the medial part of the medulla oblongata.
The infarction leads to death of the ipsilateral medullary pyramid, the ipsilateral medial leminiscus, and hypoglossal nerve fibers that pass through the medulla.
The spinothalamic tract is spared because it is located more laterally in the brainstem and is not supplied by the anterior spinal artery, but rather by the vertebral and posterior inferior cerebellar arteries. The trigeminal nucleus is also spared, since most of it is higher up in the pons, and the spinal part of it found in the medulla is lateral to the infarct.
Presentation
The condition usually consists of:
- a deviation of the tongue to the ipsilateral side of the infarct on attempted protrusion, caused by muscle weakness on the ipsilateral side due to the death of hypoglossal nerve fibers.
- limb weakness (or hemiplegia, depending on severity), on the contralateral side of the infarct, caused by damage to the medullary pyramid and hence to the corticospinal fibers of the pyramidal tract.
- a loss of discriminative touch, conscious proprioception, and vibration sense on the contralateral side of the infarct, caused by damage to the medial leminiscus.
Sensation of pain and temperature to the body and sensation to the face are preserved, due to the sparing of the medial leminiscus and trigeminal nucleus.
The syndrome is said to be "alternating" because the lesion causes symptoms both contralaterally and ipsilaterally. Sensation of pain and temperature is preserved, because the spinothalamic tract,
References
- ^ "Atlas of Microscopic Anatomy: Section 17 - Central Nervous System. Plate 17.330 Medulla Oblongata". Retrieved on 2007-06-07.
External links
- http://isc.temple.edu/neuroanatomy/lab/lesions/14.htm
- http://www.neuropat.dote.hu/table/kereszt7.htm
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- This page was last modified on 14 September 2008, at 21:16.
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