Visit request for a sleepy confused young man
The wife of 36-year-old Paul rings you at 4:30 in the afternoon. Returning home, she found Paul confused and sleepy. When she tried to wake him he started talking incomprehensible nonsense and swinging his arms and legs around. She was going to call the ambulance but Paul settled down again and was now back in bed asleep. Paul had suffered from a 'bad cold' and headaches recently. She asks if you would come and see him in the morning.
Dr Tanvir Jamil discusses.
Can this wait until morning?
Only if you want a sleepless night. The alternative of course is to explain to his wife that Paul sounds like he needs admission to hospital immediately. She should be instructed to call 999 straightaway and arrange an urgent ambulance. You could even call the ambulance for her. However, let's assume you visit Paul quickly. What are you thinking about on the way to his house? With that history encephalitis would be high on my list of differential diagnoses.
What's the difference between this and meningitis?
Encephalitis is inflammation of brain matter ('parenchyma') itself whereas meningitis is inflammation of the meninges. However, there is usually some degree of inflammation of the parenchyma in meningitis and of the meninges in encephalitis.
I guess the main causes are viral what are the usual suspects?
The commonest cause of viral encephalitis in the UK is herpes simplex (HSV), although HIV is also becoming increasingly important. Other viruses include Japanese (B) encephalitis, coxsackie, ECHO virus and rabies.
Likewise the majority of major childhood viral infections can cause varying forms of encephalitis. Measles may cause subacute sclerosing panencephalitis (SSPE) but it's rare only one in 1,000 people with measles will develop measles encephalitis. Rubella can cause progressive rubella panencephalitis. Watch for cytomegalovirus (CMV) in immunocompromised patients.
There are also some non-viral causes of encephalitis. Lyme disease (Borrelia burgdorferi) is tick borne, so don't forget to ask if they've been bitten by an insect recently. Also neurosyphillis, staph aureus and other bacteria originating from nearby areas of infection (for example the frontal sinus) may cause brain abscesses. In immunocompromised patients it is important to think about listeria and toxoplasmosis.
What about typical signs and symptoms? Is there anything in the history that could point to aetiology?
Encephalitis presents itself in a similar fashion to a brain abscess, ie a short febrile illness, malaise, chills, nausea, vomiting, headache and confusion. The inflammation of brain parenchyma can lead to a combination of seizures, mental status changes, cognitive impairment and focal neurological signs.
As there is usually very little meningeal involvement an important negative is the absence of neck stiffness. Cerebellar signs often point to chickenpox encephalitis. Herpes simplex encephalitis is typically sudden, affects the temporal lobes (look for olfactory hallucinations, behavioural disturbance, complex partial seizures) and may cause amnesia.
The good news is that IV aciclovir, given before the patient enters coma, has greatly improved the prognosis for patients with HSV encephalitis. So get the patient into hospital as soon as possible.
When I see Paul I can't be sure that it is encephalitis. What other diagnoses should I be thinking about?
You need to exclude non-viral causes. If there is any hint of neck stiffness, photophobia or rash then you must assume meningitis and give a bolus of IM penicillin stat. Other differential diagnoses include subdural haematoma, abscess, empyema, Wernickes' encephalopathy and tumours.
What kind of investigations will be carried out in hospital?
·MRI/EEG may show anatomical area affected.
·Lumbar puncture after CT screening for identification of organism. Polymerase chain reaction (PCR) of CSF for HSV DNA helps to identify organism rapidly
·Viral and immunological studies look at rising titres
·Brain tissue biopsy and culture.
Most encephalitis treatment is just supportive isn't it?
Yes, but it often needs to be given in ITU. Very ill patients are treated blind to cover for the commonest treatable causes, eg ceftriaxone + benzylpenicillin + thiamine.
Any suspicion of fulminant acute encephalitis that could be due to HSV is treated immediately with IV aciclovir. Other measures include IV mannitol (to reduce cerebral oedema), IV dextrose saline (to maintain blood glucose) and fluid restriction (to reduce cerebral oedema).
A few days after he has been admitted Paul's wife comes to see me and tells me he is still in ITU. She asks whether Paul will be completely better. What can I tell her?
Remember to follow the golden rules: find out first what she already knows or has been told by the doctors at the hospital, give her plenty of time, listen carefully and avoid jargon. You might want to cover the following points:
·Nerve cells may be damaged or destroyed by the viral infection and by pressure resulting from the inflammation some loss of brain function is therefore probably inevitable.
·It's difficult to predict how the illness will
affect any one person. In many cases impairment
can be minor. In other cases damage can be extensive, leading to significant impairments.
·Recovery is a slow process. An initial period of convalescence with plenty of rest is recommended. This should be followed by a programme of graded activity and rest over three to six months, giving the brain the opportunity to restore function.
·Tiredness, headaches, memory problems, lack of concentration and balance, temper tantrums, mood swings, depression, aggression and clumsiness are all commonly reported, as well as potential speech and language problems.
·Speed of thought and reaction may be reduced.
·Epilepsy may develop weeks or months after the illness has subsided.
·Most people are able to return to work eventually but too soon can hamper recovery.
·If a patient has had any seizures they must report this to the DVLA.
Remember to also mention that district nurses, health visitors, physiotherapists, occupational therapists and social services may all need to be involved at some stage in Paul's recovery.
You may also want to give Paul's wife the opportunity to talk about her own feelings and the way she is coping with her husband's illness.
·In encephalitis there may be meningeal inflammation
·The most common UK cause is HSV
·Herpes simplex encephalitis onset is typically sudden
·IV aciclovir pre-coma improves prognosis
·Recovery is slow, at three to six months
·Encephalitis Information Service
Tanvir Jamil is on sabbatical in Canada