Correspondence

Prevention of Eclampsia

N Engl J Med 2003; 348:2154-2155May 22, 2003

Article

To the Editor:

Belfort et al. (Jan. 23 issue)1 define the HELLP syndrome as hemolysis, elevated liver enzymes, and a platelet count below 150,000 per cubic millimeter. As the person who established the criteria for the diagnosis and named the entity the “HELLP syndrome,” I would appreciate the authors' use of the correct platelet count, as described in my original report2 and as cited in the reference they provide3: it is 100,000 platelets per cubic millimeter.

Louis Weinstein, M.D.
Medical College of Ohio, Toledo, OH 43614
lweinstein@mco.edu

3 References

1. 1

   Belfort MA, Anthony J, Saade GR, Allen JC Jr. A comparison of magnesium sulfate and nimodipine for the prevention of eclampsia. N Engl J Med 2003;348:304-311
   Full Text | Web of Science | Medline

2. 2

   Weinstein L. Syndrome of hemolysis, elevated liver enzymes, and low platelet count: a severe consequence of hypertension in pregnancy. Am J Obstet Gynecol 1982;142:159-167
   Web of Science | Medline

3. 3

   Hypertension in pregnancy. ACOG technical bulletin. No. 219. Washington, D.C.: American College of Obstetricians and Gynecologists, January 1996.
   

To the Editor:

Belfort et al. suggest that the (unknown) mechanism of action of magnesium sulfate in preventing eclamptic seizures seems to be unrelated to an improvement in cerebral vascular perfusion. Magnesium can act as a calcium antagonist, and in fact, hypermagnesemia leads to vasodilatation, counteracting brain vasoconstriction. However, glutamate may mediate ischemic neuronal damage.1 Magnesium ions physiologically block ion channels associated with the N-methyl-D-aspartate (NMDA) receptor, preventing secondary cell damage.2 Magnesium sulfate is neuroprotective in animal models of trauma, focal brain ischemia, and subarachnoid hemorrhage,3 and small trials involving patients with acute stroke and subarachnoid hemorrhage suggest that it has a beneficial effect.1 Finally, NMDA antagonists can block refractory seizures in humans.4 Could the efficacy of magnesium sulfate against eclamptic seizures be due simply to its neuroprotective, antiglutamatergic effect?

Vincenzo Bonicalzi, M.D.
Sergio Canavero, M.D.
Ospedale Molinette, 10126 Turin, Italy
vbonica@libero.it

4 References

1. 1

   Muir KW. Magnesium for neuroprotection in ischaemic stroke: rationale for use and evidence of effectiveness. CNS Drugs 2001;15:921-930
   CrossRef | Web of Science | Medline

2. 2

   Obrenovitch TP, Urenjak J. Is high extracellular glutamate the key to excitotoxicity in traumatic brain injury? J Neurotrauma 1997;14:677-698
   CrossRef | Web of Science | Medline

3. 3

   Veyna RS, Seyfried D, Burke DG, et al. Magnesium sulfate therapy after aneurysmal subarachnoid hemorrhage. J Neurosurg 2002;96:510-514
   CrossRef | Web of Science | Medline

4. 4

   Schmitt B, Netzer R, Fanconi P, Baumann P, Boltshauser E. Drug refractory epilepsy in brain damage: effect of dextromethorphan on EEG in four patients. J Neurol Neurosurg Psychiatry 1994;57:333-339
   CrossRef | Web of Science | Medline

Author/Editor Response

Dr. Weinstein notes that we used different criteria for the diagnosis of the HELLP syndrome than those he used in his report, in which he coined the term “HELLP” to describe the syndrome.1 This syndrome was described as early as the 19th century,2 and a description of it was published in the Journal in the 1950s.3 Criteria other than those of Dr. Weinstein are often used in practice, and many clinicians now refer to the presence of thrombocytopenia (defined by hematologists as a platelet count below 150,000 per cubic millimeter) in association with hemolysis and elevated liver enzymes in a patient with preeclampsia as the HELLP syndrome. In this regard, the criteria that we used (including a platelet count between 100,000 and 150,000 per cubic millimeter) are consistent with those of the Mississippi classification4 and are ones we consider most clinically applicable.

We agree with Drs. Bonicalzi and Canavero that magnesium sulfate may have a role in cerebral neuroprotection in eclampsia, by way of an antiglutamatergic effect. This is an area that deserves further investigation, since it is unlikely that magnesium sulfate exerts its effect entirely through a calcium-channel–blocking action.

Michael A. Belfort, M.D., Ph.D.
University of Utah, Salt Lake City, UT 84132
uvmbelfo@ihc.com

George R. Saade, M.D.
University of Texas Medical Branch, Galveston, TX 77555

4 References

1. 1

   Weinstein L. Syndrome of hemolysis, elevated liver enzymes, and low platelet count: a severe consequence of hypertension in pregnancy. Am J Obstet Gynecol 1982;142:159-167
   Web of Science | Medline

2. 2

   Dieckmann WJ. The toxemias of pregnancy. 2nd ed. St. Louis: Mosby, 1952:362-9.
   

3. 3

   Pritchard JA, Weisman R Jr, Ratnoff OD, Vosburgh GJ. Intravascular hemolysis, thrombocytopenia and other hematologic abnormalities associated with severe toxemia of pregnancy. N Engl J Med 1954;250:89-98
   Full Text | Web of Science | Medline

4. 4

   Martin JN, Magann EF, Isler CM. HELLP syndrome: the scope of disease and treatment. In: Belfort MA, Thornton S, Saade GR, eds. Hypertension in pregnancy. New York: Marcel Dekker, 2002:141-88.