Central pontine myelinolysis pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mohamadmostafa Jahansouz M.D.[2]
Overview
It is understood that central pontine myelinolysis is caused by the rapid correction of hyponatremia. The CNS is particularly susceptible to reductions in plasma osmolarity, specially during hyponatremia which is the most commonly encountered electrolyte disturbance. When a decrease in the plasma osmolarity happens, neural cells first swell but then they are able to regain their original volume through the release of inorganic and organic osmolytes and exit of osmotically obligated water. Subsequent exposure to hypertonic stress(e.g., correction of hyponatremia with hypertonic I.V. solutions)resulting from a rapid correction of hyponatremia causes the ions to quickly re-enter the intracellular space and compels the water to follow. If the serum sodium levels rise too rapidly, the increased extracellular tonicity will continue to drive water out of the brain's cells because the brain cells do not have enough time to bring extracellular sodium into the cell, so the water goes out very fast. This can lead to cellular dysfunction and central pontine myelinolysis and finally death.
Pathophysiology
Pathogenesis
- It is understood that central pontine myelinolysis is caused by rapid correction of hyponatremia.[1][2]
- The CNS is particularly susceptible to reductions in plasma osmolarity, specially during hyponatremia which is the most commonly encountered electrolyte disturbance.
- When a decrease in the plasma osmolarity happens, neural cells first swell but then they are able to regain their original volume through the:[2][3]
- Release of inorganic and organic osmolytes
- Exit of osmotically obligated water
- A subsequent exposure to hypertonic stress(e.g., correction of hyponatremia with hypertonic I.V. solution's)resulting from a rapid correction of hyponatremia causes the ions to quickly re-enter the intracellular space and compels the water to follow.[4][2][1]
- If the serum sodium levels rise too rapidly, the increased extracellular tonicity will continue to drive water out of the brain neurons because the brain cells do not have enough time to bring extracellular sudiom into the cell, so the water goes out very fast instead.[2][1]
- This can lead to cellular dysfunction and central pontine myelinolysis and finally death.[2][1]
Genetics
There is no association between central pontine myelinolysis and genetic factors.
Gross Pathology
- On gross pathology of patients with central pontine myelinolysis a red, central, triangular region of softening may be seen with preservation of the surrounding parenchyma on opened sagittally pons and medulla from the ventral aspect.[5]
- Central and symetrical demyelination in the base of the pons in cross section samples[6]
Microscopic Pathology
On microscopic histopathological analysis, the following features are characteristic findings of central pontine myelinolysis:[7][6]
- Loss of myelinated fibers at the base of the pons that is usually central and symmetrical but also can be neither
- The lesions are sharply demarcated and contain sheets of lipid‐laden macrophages and large numbers of reactive astrocytes.
- Infiltration by lymphocytes is sparse or absent.
- Axons and neurons are mostly well preserved.
- Symmetrically spared “islands” of myelinated white matter
References
- ↑ 1.0 1.1 1.2 1.3 Mascarenhas JV, Jude EB (2014). "Central pontine myelinolysis: electrolytes and beyond". BMJ Case Rep. 2014. doi:10.1136/bcr-2013-203516. PMC 3975522. PMID 24682140.
- ↑ 2.0 2.1 2.2 2.3 2.4 Khosya S, Meena H (2013). "Central pontine myelinolysis". Indian J Med Res. 137 (5): 993–4. PMC 3734697. PMID 23760391.
- ↑ Burg MB, Ferraris JD (2008) Intracellular organic osmolytes: function and regulation. J Biol Chem 283 (12):7309-13. DOI:10.1074/jbc.R700042200 PMID: 18256030
- ↑ Sheikh AB, Afzal RM, Sagheer S, Bukhari MM, Javed A, Nasrullah A et al. z (2018). "The Dilemma of Inadvertent Pontine Demyelinosis: A Review of Literature". Cureus. 10 (8): e3174. doi:10.7759/cureus.3174. PMC 6197531. PMID 30357070.
- ↑ Haynes HR, Gallagher PJ, Cordaro A, Likeman M, Love S (2018). "A case of chronic asymptomatic central pontine myelinolysis with histological evidence of remyelination". Forensic Sci Med Pathol. 14 (1): 106–108. doi:10.1007/s12024-017-9933-y. PMC 5830465. PMID 29177819.
- ↑ 6.0 6.1 Robinson CA, Adiele RC, Tham M, Lucchinetti CF, Popescu BF (2014). "Early and widespread injury of astrocytes in the absence of demyelination in acute haemorrhagic leukoencephalitis". Acta Neuropathol Commun. 2: 52. doi:10.1186/2051-5960-2-52. PMC 4035095. PMID 24887055.
- ↑ Love S (2006). "Demyelinating diseases". J Clin Pathol. 59 (11): 1151–9. doi:10.1136/jcp.2005.031195. PMC 1860500. PMID 17071802.