A brief description about the possible d/d of fever with alteration of sensorium and how to approach the diagnosis through systematic yet focused history taking , physical examination and lab and radiological investigations.
MIS – meningeal irritation signsFD- focal deficitsIVH/SAH – intraventricularhaemorrhage/subarachnoid haemorrhage
Approach to a case of Fever with altered sensorium
Fever with altered sensorium
Dept Of Medicine
Burdwan Medical College
A patient with fever and altered sensorium constitutes
a medical emergency.
Early recognition, efficient decision making and rapid
institution of therapy can be life saving.
Levels of consciousness:
Alert: Fully conscious
Lethargic: Appear somnolent, but may be able to
Obtunded: Requires touch or voice to maintain arousal.
Stuporous: Unresponsiveness from which the individual
can be aroused only by painful stimulus.
Comatose: State in which patient is unable to arouse or
respond to noxious stimuli and is completely unaware
of self and surroundings.
Fever with altered sensorium-- causes
Brain abscess, subdural or
• Sepsis associated
• Sepsis with DIC/TTP
B. NON INFECTIOUS CAUSES OF FEVER
a. OVERPRODUCTION OF HEAT :
1. Neuroleptic malignant syndrome
2. Malignant Hyperthermia.
4.Cocaine, Amphetamine, ecstasy toxicity
7.Convulsive status epilepticus.
b. IMPAIRED HEAT DISSIPATION
1.Anticholinergic toxicity e.g amitriptyline
c. STRUCTURAL LESIONS( IMPAIRED
2.Brainstem lesion( stroke)
3.Intraventricular and subarachnoid haemorrhage
ICH with Intraventricular extension
1. ADEM(infectious or post infectious)
2.cerebral fat embolism
3.Altered sensorium with secondary cause of fever eg. Aspiration
pneumonia in a stroke patient.
Presence of fever alone is not sufficient to make a diagnosis of
an infectious etiology( e.g Meningitis or encephalitis)
Encephalopathy may be precipitated by systemic infections or
sepsis without cerebral inflammation (septic encephalopathy)
Sepsis can lead to altered sensorium secondary to metabolic
alterations like hypoglycaemia
, hyperpyrexia, hypovolemia, hepatic or renal failure.
Even in absence of infection there can be high rise of temp due
to mechanisms such as overproduction or impaired dissipation
of heat, non infectious CNS diseases, hypothalamic lesion.
Patients of NMS may have fever, neck stiffness, delirium,
generalised rigidity, even after the offending drug has been
WORLDWIDE , infection of the CNS is the
commonest cause of Fever with altered sensorium.
In a study from India among children < 18 yrs of age,
commonest cause of acute febrile encephalopathy was
VIRAL MENINGITIS, accounting for 40% of the cases.
Among non viral, bacterial ( 34%), tubercular meningitis
(7.9%) and cerebral malaria (5.2%) were most common.
Causes of infectious meningoencephalitis:
a. DNA virus:
1. Herpes viruses: herpes simplex (HSV1,HSV2)
other herpes viruses (HHV6, EBV, VZV, CMV)
b. RNA viruses:
Influenza, Polio, Entero,
Measles, Rubella, Mumps,
Rabies, Arbo, Reo, & Retrovirus
Rickettsia rickettsii, R. typhi,
Cryptococcosis, coccidiomycosis, histoplasmosis, blastom
Plasmodium, trypanosoma, Toxoplasma, Naegleria, schist
APPROACH TO THE PATIENT
Sometimes only clue to correct
Careful and systematic clinical
assessment is key to management of
a patient of febrile encephalopathy.
Imp to differentiate infective vs non
Temporal course is also imp –
whether fever preceded or followed
altered sensorium or simultaneous.
Classical triad of CNS inf – fever,
neck rigidity, altered mental status.
(present in majority of patients)
HISTORY: imp points:
Onset of altered sensorium
Fever – grade/type
Joint pain /rashes
Contact with animals/dog bite
Seizures – imp in children
Drug addiction/use of antipsychotics
Treatment with immunosuppressants/chemotherapy
Comorbidity such as diabetes
Thorough physical examination & neurological examination can
provide imp clues to underlying aetiology.
Skin rashes are common in meningococcal infn, rickettsial fever, VZV,
colorado tick fever
Parotitis in mumps
Erythema nodosum may be a/w TB
mucous membrane lesions common in Herpes virus infn,
Upper resp tract infn favour Influenzae or Mycoplasma
Look for lymphadenopathy, hepatosplenomegaly.
Detailed neurological examination including
Pupillary size(anisocoria) & reaction(loss)
Forced eye deviation,
Cranial nerve involvement,
Focal neuro deficit,
Fundus examination for papilloedema help in diagnosis &
Common focal abnormalities are
Hemiparesis, Aphasia, Ataxia,
Pyramidal Signs, Cranial Nerve Deficits,
Involuntary Movements (Myoclonus & Tremors),
Partial Seizures & Papilloedema.
warrant neuroimaging prior to LP
Signs of suspected meningitis:
Kernig sign: flexing hip & extending knee – elicit
pain in back n legs.
Brudzinski sign: passive flexion of neck elicits
flexion of hip
Nuchal rigidity: severe neck stiffness.
Jolt accentuation: exacerbation of existing headache
with rapid head rotation
After getting clues from History and
investigations are tailored as per
TC, DC - CBC
Blood culture: +ve in 30-80% cases of
Serum CRP & Procalcitonin
Arterial blood gases
Relative lymphocytosis in viral meningitis.
Leucopenia & thrombocytopenia – in
rickettsial infn & viral haemorrhagic fevers.
For definitive diagnosis of malarial infn
P. falciparum gamet
May reveal changes suggestive of infn such as
Mycoplasma, Legionella, Tuberculosis
Always indicated when meningitis or meningoencephalitis is
Gross examination for turbidity, cob web coagulum
Chemical examination: sugar, protein
Cell count & cell types
Microbiological examination: gram stain, india ink
PCR for tuberculosis, viral infn
Limulus lysate assay
lymphocytes lymphocytes PMNs
Characteristic neuroimaging changes:
Fronto temporal changes in HSV
Thalamic & midbrain changes in Japanese encephalitis
Basal exudates after contrast adm in TB Meningitis.
Basal ganglia ring enhancing lesion in Toxoplasmosis.
Multiple ring enhancing lesions in tuberculoma.
imp to rule out non convulsive status.
d/d of focal encephalitis vs generalised encephalopathy
Characteristic EEG changes:
Diffuse bihemispheric slowing in gen.
Triphasic slow waves in hep encephalopathy.
2-3 Hz, periodic lateralised epileptiform
discharges from temporal lobe in HSV.
Thyroid function test
Urine toxicology screen
Patient with Fever and altered sensorium
Precipitant known – drugs/toxins/heat
Treat acc to cause
Sudden onset altered
sensorium followed by fever
Seizure, psychiatric features/
minimal MIS/ FD +/-
Fever f/b altered sesorium
Fever f/b altered sesorium
MRI brain/ CSF
Brain stem stroke,
hypothalamic lesion &