Seizures DDx

Overview

• Seizures are the manifestation of abnormal hyperexcitable discharges of cortical neurons.
• 10 minutes of continuous seizure activity is now considered status epilepticus, which may result in neuronal damage. Seizures should be aggressively treated if they last longer than 5 minutes.
• International League Against Epilepsy (ILAE) and the International Bureau for Epilepsy (IBE) in 2005 definition of epilepsy: brain disorder characterized by an enduring predisposition to generate epileptic seizures and by the neurobiologic, cognitive, psychologic, and social consequences of this condition.
• Traditionally, the diagnosis of epilepsy requires the occurrence of at least 2 unprovoked seizures 24 hours apart.

Causes

Epilepsy

• May be the first presentation
• Noncompliance with anticonvulsant therapy
• May be triggered by specific factors, e.g. sleep deprivation, medications (e.g. tramadol, antipsychotics that lower the seizure threshold), intercurrent illness

Other conditions which cause generalized or focal CNS injury can also precipitate or perpetuate seizures

• Hypoxia
• Metabolic disturbances (e.g. hypoglycaemia, uremia, hepatic encephalopathy)
• Electrolyte imbalance (e.g. hyponatraemia, hypernatraemia, hypercalcaemia)
• Drug intoxication (e.g. anticonvulsants, antidepressants, antipsychotics, isoniazid, opioids, theophylline, sympathomimetics)
• Drug withdrawal (e.g. alcohol, barbiturates, benzodiazepines)
• Trauma
• CNS neoplasia
• Stroke
• Intracranial haemorrhage (e.g. subrachnoid hemorrhage, intracerebral hemorrhage)
• CNS infection (e.g. meningoencephalitis, cerebral abscess, neurocysticercosis)

Types of seizures

Trieman classification system of status epilepticus

• Generalized convulsive SE
• Subtle SE (very poor prognosis)
• Nonconvulsive SE
• Absence SE
• Complex partial SE
• Simple partial SE

Differential diagnosis of conditions that mimic seizures

• Eclampsia
• Nonepileptic seizures/ pseudoseizures
• Syncope
• Acute dystonic reactions
• Rigors
• Cardiac disorders (e.g. Dysrhythmias, Long QT syndrome, HOCM)

Mnemonics

“SICK DRIFTER”

• Substrates (sugar, oxygen)
• Isoniazid overdose
• Cations (Na, Ca, Mg)
• Kids (eclampsia)
• Drugs (CRAP: Cocaine, Rum (alcohol), Amphetamines, PCP)
• Rum (alcohol withdrawal)
• Illnesses (chronic seizure disorder or other chronic disorder)
• Fever (meningitis, encephalitis, abscess)
• Trauma (epidural, subdural, intraparynchymal hemorrhage)
• Extra: toxocologic (TAIL: Theo, ASA, Isoniazid, Lithium) and 3 Anti’s: (Antihistamine overdose, Antidepressant overdose, Anticonvulsants (too high dilanitin, tegretol) or benzo withdrawal.
• Rat poison (organophospates poisoning – not actually rat poison!)

CCC Differential Diagnosis Series
NEURO	Anosmia, Ataxia, Blepharospasm, Bulbar and Pseudobulbar palsy, Central Pontine Myelinosis, Cerebellar Disease, Chorea, Cranial nerve lesions, Dementia, Dystonia, Exophthalmos, Eye trauma, Facial twitches, Fixed dilated pupil, Horner syndrome, Loss of vision, Meningism, Movement disorders, Optic disc abnormality, Parkinsonism, Peripheral neuropathy, Radiculopathy, Red eye, Retinal Haemorrhage, Seizures, Sudden severe headache, Tremor, Tunnel vision
RESP	Bronchial breath sounds, Bronchiectasis, High airway pressures, Massive haemoptysis, Sore throat, Tracheal displacement
CVS	Atrial Fibrillation, Bradycardia, Cardiac Failure, Chest Pain, Murmurs, Post-resuscitation syndrome, Pulseless Electrical Activity (PEA), Pulsus Paradoxus, Shock, Supraventricular tachycardia (SVT), Tachycardia, VT and VF, SVC Obstruction
GIT	Abdominal distension, Abdominal mass, Abdominal pain, Asterixis, Dysphagia, Hepatomegaly, Hepatosplenomegaly, Large bowel obstruction, Liver palpation abnormalities, Lower GI haemorrhage, Malabsorption, Medical causes of abdominal pain, Rectal mass, Small bowel obstruction, Upper GI Haemorrhage
GUT	Genital ulcers, Groin lump, Scrotal mass, Urine colour, Urine Odour, Urine transparency,
MSK	Arthritis, Shoulder pain, Wasting of the small muscles of the hand
DERM	Palmar erythema, Serious skin signs in sick patients, Thickened Tethered Skin, Leg ulcers, Skin Tumour, Acanthosis Nigricans
ENDO	Diabetes Insipidus, Diffuse Goitre, Gynaecomastia, Hirsutism, Hypoglycaemia, SIADH, Weight Loss
HAEM	Splenomegaly
PAEDS	Floppy infant
MISC	Anaphylaxis, Autoimmune associated diseases, Clubbing, Parotid Swelling, Splinter haemorrhages, Toxic agents and abnormal vitals, Toxicological causes of cardiac arrest
IMAGING	CHEST: Atelectasis, Hilar adenopathy, Hilar enlargement on CXR, Honeycomb lung, Increased interstitial markings, Mediastinal widening on mobile CXR, Pulmonary fibrosis, Pseudoinfiltrates on CXR, Pulmonary opacities on CXR, ABDO: Gas on abdominal X-ray, Kidney mass, BRAIN: Intracranial calcification, Intracranial structures with contrast, Ventriculomegaly, OTHER: Pseudofracture on X-Ray,
LABS	LOW: Anaemia, Hypocalcaemia, hypochloraemia, Hypomagnesaemia,  HIGH: Bilirubin and Jaundice, Hyperammonaemia, Hypercalcaemia, Hyperchloraemia, Hyperkalaemia, Hypermagnesaemia,  ACID BASE: Acid base disorders, Resp. acidosis, Resp. alkalosis, Creatinine, CRP, Dipstick Urinalysis, Laboratory Urinalysis, Liver function tests (LFTs), Pleural fluid analysis, Urea, Urea Creatinine Ratio, Uric acid, Urinalysis, Urine Electrolytes

[cite]