Acute Disseminated Encephalomyelitis

Also known as: ADEM

Acute disseminated encephalomyelitis (ADEM) is a monophasic, immune-mediated demyelinating disorder of the CNS, typically occurring 1 to 4 weeks after a viral infection or, less commonly, vaccination, thought to reflect molecular mimicry triggering an autoimmune attack on CNS myelin.

Predominantly affects children, and, by definition, is monophasic, distinguishing it from multiple sclerosis, though a minority of cases later prove to be a first MS episode.

MRI brain and spinal cord shows multiple, large, poorly demarcated T2/FLAIR hyperintense lesions in white matter, often with deep gray matter (basal ganglia, thalamus) involvement, distinguishing the pattern from typical MS lesions.

CSF shows a lymphocytic pleocytosis with elevated protein; oligoclonal bands are typically absent or transient (unlike MS, where they are usually persistent), an important discriminating feature.

Infectious encephalitis (particularly HSV) must be excluded given overlapping presentation, with CSF PCR as detailed in that entry.

High-dose IV corticosteroids (methylprednisolone 1 g IV od for 3 to 5 days), followed by an oral taper over 4 to 6 weeks, is first line
IVIG or plasma exchange for steroid-refractory or severe cases
Supportive care and rehabilitation for residual deficits
Most children make a good recovery; a minority have residual deficits or, over subsequent follow-up, are reclassified as having had an initial MS attack if further demyelinating episodes occur, warranting long-term neurological follow-up

Referral: neurology for all cases, given diagnostic overlap with MS and the need for long-term follow-up.

Status Epilepticus

Also known as: Convulsive status

A single seizure lasting >5 minutes, or recurrent seizures without full recovery of consciousness between episodes; the 5-minute threshold (rather than the traditional 30 minutes) reflects evidence that seizures rarely self-terminate after this point and that earlier treatment improves outcomes.

Medical emergency with significant morbidity/mortality risk from the seizure itself and the underlying cause.

Classified by:

Convulsive status epilepticus: generalized tonic-clonic activity ; most dangerous, highest mortality
Non-convulsive status epilepticus: altered consciousness/behavior without prominent motor activity, diagnosed via EEG; often underrecognized
Refractory status epilepticus: persists despite adequate doses of benzodiazepine + one second-line AED
Super-refractory status epilepticus: continues/recurs ≥24 hours after anesthetic therapy initiation

Ongoing generalized tonic-clonic movements, or repeated seizures without inter-ictal recovery of consciousness
Progressive physiological derangement with prolonged seizure activity: hyperthermia, hypoxia, lactic acidosis, rhabdomyolysis, autonomic instability, cerebral edema risk
Non-convulsive status: subtle motor signs (twitching, nystagmus), fluctuating consciousness, behavioral change, unexplained confusion ; high index of suspicion needed, especially post-convulsive seizure with failure to regain baseline consciousness
Identify precipitant: known epilepsy with medication non-adherence/illness/sleep deprivation, new structural lesion, metabolic derangement (hypoglycemia, hyponatremia, hypocalcemia), CNS infection, alcohol withdrawal, drug toxicity/overdose, eclampsia, hypoxic brain injury

Clinical diagnosis based on observed seizure duration and pattern; treatment should NOT be delayed for investigations in convulsive status.

Immediate bedside tests (during/immediately after initiating treatment):

Capillary glucose; mandatory, correct hypoglycemia immediately if present
Vital signs, SpO2, temperature

Investigations (once treatment initiated, to identify cause):

U&E, calcium, magnesium, LFTs, FBC
AED levels if on known anticonvulsants
Toxicology screen, alcohol level if relevant
Blood cultures, lumbar puncture if infection suspected (CT head first if focal signs/raised ICP concern)
CT head: if first presentation, focal neurological signs, head trauma, or failure to improve as expected
EEG: for suspected non-convulsive status, or to confirm cessation of electrographic seizure activity in a paralyzed/sedated patient; clinical convulsions stop with paralytics but electrographic seizures can continue undetected

Differentials: psychogenic non-epileptic seizures, rigors, decerebrate/decorticate posturing, extreme agitation/dystonic reaction.

Time-based, stepwise protocol; treat aggressively and promptly, do not wait to "see if it stops".

0-5 minutes:

ABC assessment, oxygen, IV access, glucose check (correct hypoglycemia: IV dextrose ± thiamine first if alcohol use disorder suspected), position to prevent injury/aspiration, note exact time of onset

5-10 minutes; first-line, benzodiazepine:

IV lorazepam 4mg (adult), repeat once after 5-10 minutes if seizure continues (0.1mg/kg in children, max 4mg per dose)
If no IV access: buccal midazolam 10mg, or rectal diazepam 10-20mg, or IM midazolam 10mg

10-30 minutes ; second-line, if still seizing after 2 benzodiazepine doses:

IV levetiracetam 60mg/kg (max 4.5g) over 15 min, OR
IV valproate 40mg/kg (max 3g) over 10 min (avoid in pregnancy/known hepatic disease), OR
IV phenytoin 20mg/kg (max 2g) over 20-30 min with cardiac monitoring (hypotension, arrhythmia, purple glove syndrome risk) : fosphenytoin preferred where available
Choice guided by patient factors rather than strict hierarchy (ESETT trial showed similar efficacy)

30-60 minutes ; refractory status, anesthesia required:

Rapid sequence induction and intubation, general anesthesia: propofol, midazolam infusion, or thiopental ;ICU admission mandatory
Continuous EEG monitoring essential once paralyzed/sedated; titrate anesthetic to seizure suppression or burst-suppression
Continue/add maintenance AED alongside anesthesia

Super-refractory status (>24h despite anesthesia): consider ketamine infusion, inhalational anesthetics, immunotherapy if autoimmune encephalitis suspected, ketogenic diet; tertiary neurocritical care involvement essential.

Throughout: identify and treat underlying cause simultaneously, monitor for and manage complications (hyperthermia; active cooling, rhabdomyolysis ; aggressive IV fluids, aspiration pneumonia, cardiac arrhythmia).

Post-stabilization: establish/optimize maintenance AED therapy, address precipitant, EEG to confirm resolution, neurology follow-up, driving/safety counseling.

Acute Disseminated Encephalomyelitis

Overview

Clinical Features

Diagnosis

Management

Overview

Clinical Features

Diagnosis

Management