Crossing The Blood Brain Barrier: Treatment of Meningitis.

THIS DISCUSSION WOULD NOT BE COMPLETE WITHOUT INCLUDING MENTION OF HERPES ENCEPHALITIS BECAUSE THE APPROACH TO MANAGEMENT HAS TO ALSO BE RAPID AND WITHOUT TESTING AND I DISCUSS IT BELOW.  YOU MAY SEE ONLY ONE CASE IN YOUR ENTIRE CAREER BUT IF YOU SEE AN AGITATED TEENAGER WITH A COLD SORE THAT MAY BE HERPES ENCEPHALITIS AND THE DECISION TO TREAT IS DONE WITHOUT ANY TESTS AND SHOULD BE IMMEDIATE.  THE DX MAY BE MADE BY MRI IN LATE CASES OR BY BRAIN BIOPSY.

If you have a case of meningitis in the ED you have a serious and lethal infection that is a risk to both staff as well as the patient.  The early descriptions of meningitis include a child or infant who is persistently crying or somnolent (or anything along a spectrum of state of consciousness) who presents with fever, likely no stiff neck if <2years of age and a “purple skin rash that is evolving even in cases that are treated correctly!  Meningitis has many mimicker illnesses and the rash can lead one to an alternate incorrect diagnosis.

I will start with some basics.  What are the primary bacterial organisms by age group that cause meningitis?

Newborns: E Coli (acquired from the mother during vaginal delivery) and even group B strep.

2-3 Months Old: Listeria monocytogenes which requires that Ampicillin in intravenous form be added to a 3rd generation Cephalosporin (FYI: alcoholic adults are also at risk for Listeria meningitis)

3 months to 1 year and beyond:  Still the common pathogens we have had for decades.  There are six types of hemophilus but type B causes infections most commonly in humans and despite vaccinations we still have hemophilus influenza meningitis and other infections caused by this organism.  The most common organism now is the well known encapsulated Streptocococcus pneumoniae aka pneumococcus infection.  

Finally, anyone with a skin rash, fever, altered mentation of any type has to be considered for meningoccocal infection and may have not ever received the vaccine although in the US all school age children are vaccinated just as they are also vaccinated for type A/B hepatitis in two series and also like the standard immunizations for childhood diseases.  Some are never vaccinated: parents don’t believe in the vaccination(s), they even think they are harmful and in some US subcultures are never accepted.  Meningococcus can kill in minutes from the time of arrival to an ED.  The sequence is always then to adminster the antibiotics and then perform a lumbar puncture and inform the lab which antibiotic(s) were administered.  The ABCs and any problem issues must be corrected and the patient needs to be isolated.  Immunoflorescent and immunoassay technology and other testing of the CSF can prove the presence of the organism if it is causing meningitis (meaning it will be found in the CSF).

Some patients who present with the symptoms of meningitis and have an initial negative CSF laboratory assessment are still treated as meningitis, admitted and a delayed repeat lumbar puncture performed.  It may then show the presence of the organism.

Pneumococcus and Meningococcus are the number one causes of meningitis from age beyond 3 months throughout adulthood.  Remembering, again, that Listeria monocytogenes is high on your differential list in any alcoholic.  Exposed staff may have to receive prophylaxis for meningococcal meningitis., e.g., if they had a significant exposure especially if they administered mouth to mouth resuscitation and have not been vaccinated, e.g., with rifampin.

Meningitis can be viral or bacterial.  Viral meningitis still may require admission.  Adults with good family support can be managed, in some cases, at home if the diagnosis is assured and symptoms are mild and controlled prior to discharge.  Most are initially still monitored for 24 hours in a hospital and treated for bacterial meningitis until/unless their lab assessment of their CSF supports a diagnosis of viral meningitis.  There is one special case of viral meningitis/encephalitis that people carry all of their lives and it is the patient with herpes on the face who are at risk and it can be rapidly fatal and requires immediate treatment with Acyclovir, or one of the newer similar agents intravenously or the patient can sustain fatal damage to both temporal lobes.  The provider who sees any agitated patient with a fever blister (cold sore) should assume herpes encephalitis and treat empirically without waiting for any tests because the treatment is innocuous and the disease highly and rapidly fatal.  The LP again may not show enough information to make this diagnosis and it is often only proven by brain biopsy.  This is almost never performed because informed physicians know to treat.  It can be either type I or type II herpes on the face…when it activates it moves retrograde and cephalic into the brain along the cranial nerves but the most common is travel and infection of both temporal lobes simultaneously.

THE SEQUENCE of [ACLS] is the management sequence: A->C->L->S to remember:  A = antibiotic (antiviral), next CT scan if you need to rule out increased intracranial pressure but this is often easily done if the provider learns ophthalmologic examination of the eye and now even US of the globe can prove that there is no increased intracranial pressure.  This means that the next procedure is safe to perform and that is lumbar puncture (the L).  The S is for Steroid which is to inhibit the damage caused by antigens from encapsulated bacteria as they are destroyed by the antibiotic and this prevents hearing loss).  more to follow…DDC

REMEMBER THAT THE USE OF ANTIBIOTICS ONLY AFFECTS A SMALL PERCENTAGE OF LUMBAR PUNCTURE CULTURES AND THEIR ARE OTHER TESTS FOR BACTERIAL ANTIGENS EVEN IF THE CULTURE IS NEGATIVE THAT CAN STILL PROVE THE DIAGNOSIS.  THE ONLY REASON TO PERFORM A CT OF THE BRAIN IS IF YOU CANNOT DETERMINE CLINICALLY THERE IS NO PAPILEDEMA I.E.., NO INCREASED INTRACRANIAL PRESSURE [ICP].  TODAY THIS CAN BE DONE BY DIRECT VISUALIZATION OF THE FUNDI BILATERALLY AND NOW BY EVALUATION OF THE OPTIC SHEATH USING BEDSIDE ULTRASOUND.  THERE ARE NUMERICAL CRITERIAL FOR THE DIAMETER OF THE OPTIC SHEATH USING ULTRASOUND IN CHILDREN AND ADULTS THAT PROVE THERE IS NO INCREASED INTRACRANIAL PRESSURE.  FINALLY,  ANY PATIENT WHO IS LAYING SUPINE WHO HAS OBVIOUS VENOUS PULSATIONS IN THE FUNDI CANNOT HAVE INCREASED INTRACRANIAL PRESSURE.  THE CONCERN IS OFTEN OVERSTATED AND THE VAST MAJORITY OF PATIENTS CAN HAVE A LUBAR PUNCTURE AND IT IS NEEDED AS A TEST OF CHOICE TO MAKE THE DIAGNOSIS IN MOST CASES.  IT MAY ALSO REQUIRE DELAYED LP 4-8 HOURS AFTER ADMISSION TO THE HOSPITAL IF THE INITIAL LP IN THE ED IS NEGATIVE.

Q:  What are the lumbar puncture findings that indicate bacterial or viral meningitis?…to be continued…DDC

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