Meningitis or encephalitis?

Let us discuss viral encephalitis in this post. First what do we mean when we say a patient has encephalitis and how does encephalitis differ from meningitis.

Meningitis is inflammation of the meninges of the brain. The meninges are the thin layers which cover the brain and include from inwards outwards pia mater, arachnoid mater and dura mater. When they get inflammed usually due to an infectious etiology a patient develops meningitis. There are numerous causes of meningits and they can be classified as bacterial causes (common bacteria which cause meningits include Haemophilus Influenzae type B, Nesseria meningitidis, Streptococcus pneumoniae, Listeria), viral causes (most of the viruses which cause meningitis are seasonal viruses and usually it is hard to isolate them. We do not try too hard to find out the particular virus causing the meningits as viral meningitis is usually self limited and has a good outcome with most patients recovering completely), fungal causes, parasitic causes and so on. So how does meningits present clinically? Patients usually have complaint of fever, headache and stiff neck. They feel tired and listless and may also have nausea and vomiting. Patients who have meningitis are bothered by bright light (we call this photophobia and hence they prefer to lie in a quiet dark room), loud sounds are also bothersome (we call this phonophobia). When we assess such patients clinically we look for tell-tale signs of meningitis: namely we check for neck stiffness (neck stiffness in a febrile patient is quite sensitive for meningitis). Patients with meningitis at least initially in their disease course are awake and alert and do not present with seizures (remember it is the meninges which are involved not the brain itself at least initally). Later on if the meningitis remains untreated patients become stuporous and comatosed. Bacterial meningitis as compared to viral meningitis is more fulminant and if untreated can prove fatal (bacterial meningitis patients usually look more “sick” as compared to those with viral meningitis). Once the diagnosis of meningitis is entertained we usually admit these patients to the hospital (some patients with viral meningitis may be managed on an outpatient basis if close supervision can be ensured). A CT scan is usually done next followed by a spinal tap to get some cerebrospinal fluid. This fluid is then sent for various tests. The diagnosis is confirmed if the spinal fluid shows inflammatory cells. On the basis of tests on the spinal fluid we can determine whether the patient has bacterial, viral, fungal or tubercular meningitis (each type has its own spinal fluid characteristic. Moreover we examine the fluid under the microscope and further culture it to isolate the organism). As you can imagine, it takes time for some of these tests to come back, so patients may be empirically started on antibiotics pending CSF culture results. Once the CSF results come back, the antibiotics can be changed depending upon which organism is isolated from the CSF.

So then what is encephalitis and how does it differ from meningitis. Encephalitis simply put is inflammation of the brain itself (not the meninges). Usually the term is used in connection with a viral etiology. The common causes of encephalitis include viruses like herpes simplex, cytomegalovirus, West Nile, flaviviruses to name a few and the common encephalitis are: herpes simplex encephalitis, Japanese encephalitis, Eastern Equine and Western Equine encephalitis, California encephalitis and tick-borne and arthropod borne encephalitis (such as Lyme encephalitis). Since in encephalitis the brain parenchyma is involved, these patients may present with depressed level of consciousness, altered personality, abnormal behavior and seizures. Usually in encephalitis the brain MRI is abnormal and gives us a hint to the extent of brain parenchymal involvement. The spinal fluid may show inflammatory cells (some patients have a component of meningitis along with their encephalitis: MENINGOENCEPHALITIS). Doctors may also order other tests like EEG to rule out seizures. The treatment of encephalitis varies. In the case of herpes encephalitis we use anti-viral drugs like acyclovir. In other encephalitis the treatment is more supportive. Some patients recover (those detected and treated in time), others are left behind with devastating neurological sequelae


Nitin Sethi, MD

4 thoughts on “Meningitis or encephalitis?

  1. my daugter was 21 years old and wastaken to the er by ambulance for seziure which she never had before. The er doctor did some tests X_RAY blood work and said he was sure it was not menniginits and diagnoised her with seziure disorder and released her. The next day nov18 2006 she still was not getting better so took her to the clinic. The DR. read her hospital report did some blood work said her white count was still high but said it was not menningitis but the flu. Gave her a shot for her headache and a shot for vomiting and released her. That night she again went by ambulance to anoter er where a lumbar puncture was performed and was positive for viral menningitis as well as herpes simplex enephalitis. My daughter responded well at first but on NOv. @@ went into cardiac arrest and life support was withdrew Nov. 23 Does the time of treatment make a difference for recovery? The Dept. Of Health Investigation found that the clinic Dr. did not provide my daughter proper care and still am waiting for the result of the Er doctor, Please I need any Answers I Tried to get my daughter the medical care she needed and trusted these DR with their answers I just never want this to happen to some one else

  2. Dear Cheri,
    I feel your pain and hope God gives you strength in these difficult times. While I cannot answer questions specifically with respect to your daughter’s case (as I do not have the facts), meningitis and encephalitis do warrant timely treatment. While viral meningitis is not as fulminant as bacterial meningitis, herpes encephalitis can cause increase in intracranial pressure (swelling in the brain). Once herpes encephalitis is suspected, it warrants immediate/early confirmation of diagnosis and adequate treatment with anti-viral drugs. You can read more about herpes encephalitis on my website
    Personal Regards,
    Nitin Sethi, MD

  3. Thank you for writing in. My selection of topics is usually based on patients I see in my office or in the hospital.

    Personal Regards,
    Nitin Sethi, MD

  4. I had a lumber puncture done in an ER.The ER doc then had me taken home 2.5 hrs later.I was brought back up to a different closer hospital within 4 hour of the LP now drowsy.I was refused care and my condition immediately labeled as a psychiatric problem.
    My first visit to the hospital a week earlier I had complained of pains in my legs and red spots in my groin.The red spots turned a blue/purple color and spread.Then two more hospital visits with headache and nausea..
    The ER doctor that did the Lumber Puncture lied about the real condition I had been in..He lied on the glasgow coma scale also..
    So I was left photo-phobic, with an inflamed body and brain left in drowsy state and refused care from this hospital that they set out to make it look like my incapacitated condition is the result of mental illness.The hospital was concealing everything from my family and withheld all blood/urine test results ..My spouse was away at this time and they went to great length to tell him I am just mentally ill.He would bring me back to hospital ERs over 40 asking why I was not walking,talking or eating..I would eventually be taken by police and put in a psychiatric ward and then they were secretly bringing doctors over to there to treat me medically..There I would be kept and given the intervenous IV antibiotics that I needed at the time of the LP.All the while lying and convincing my family that I was mentally ill..As it stands now I am suffering greatly with the damage this has done..What I am facing now is concealment of damage..In other words all my injures are being hidden..I did file complaints and they were unwilling to investigate any of this. More Cover up..Also I suspect fraud is being committed in my diagnostic test reports and once I brought up that issue I was then refuse any tests at all..This includes an MRI of my spine that I would be paying for..I know I have a damaged spine and i suspect organ damage but they have made if impossible for me to get the tests..

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