All that blacks out is not syncope: a neurological view of transient loss of consciousness - Dr Simon Taggart Consultant Clinical ...

All that blacks out is not syncope:
 a neurological view of transient
       loss of consciousness
            Dr Simon Taggart
   Consultant Clinical Neurophysiologist.
          JCUH, Middlesbrough.

Misdiagnosis of Blackouts
• Sutula 1981: 20% of patients with refractory epilepsy in
  tertiary centre had non-epileptic seizures

• Smith et al 1999: 25% of patients referred to tertiary
  epilepsy centre had non-epileptic seizures.

• Zaidi et al 2000: alternative diagnosis found in 36% of
  patients on anti-epileptic drugs

Mortality in Blackouts
•   Increased in syncope
     – At 5years, 50.5% in cardiac syncope, 24.1% in syncope of unknown
       cause

•   Increased in epilepsy
     – SMR 2.1(1.8-2.4)1, 2.3(1.9-2.6)2
     – Related to cause of epilepsy (eg brain tumour)
     – Directly or indirectly from epileptic seizures (status epilepticus,
       accidental drowning)
     – SUDEP: Sudden, unexpected, witnessed or unwitnessed, nontraumatic
       and nondrowning death in patients with epilepsy with or without
       evidence for a seizure, and excluding documented status epilepticus, in
       which post mortem examination does not reveal a (structural or
       toxicologic) cause for death.

         1. Lhatoo et al Annals of Neurol 2001: 49(3); 336-344   2. Hauser et al,
         Epilepsia 1980: 21(4); 399-412

Differential diagnosis of Blackouts
              (non-exhaustive)
•   Syncope
•   Epilepsy
•   Psychogenic non-epileptic seizures
•   Cataplexy
•   Transient CSF obstruction
•   Transient ischaemic attack - anterior and posterior
    circulation
•   Panic attack
•   Falls
•   Hypoglycaemia
•   Basilar migraine

Blackouts – clinical diagnosis:
             individual attacks
• Subjective account
  – 12 hours before, several hours after

• 1st hand witness accounts
  –   Second by second account
  –   Ban medical jargon from descriptions
  –   Strip out second hand descriptions
  –   First worst and last episodes

• 2nd hand accounts
  – Much less informative, much more misleading

Syncope v GTCS
  During blackout                                   Syncope                               Generalised tonic clonic
                                                                                                  seizure
       Pallor                                       Common                                              Rare

     Cyanosis                                          Rare                                          Common

 Duration of loss of                              60seconds
  consciousness
    Movements                        A few clonic or myoclonic jerks;                   Prolonged tonic phase (~30
                                         brief tonic posturing (few                    sec), then prolonged rhythmic
                                      seconds); duration 1 min
                                               consciousness
Lateral tongue biting                                  Rare                                          Common
  Hypersalivation                                      Rare                                          Common

        EEG                                  Generalised slowing                                Ictal EEG pattern

        Adapted from Hirsch L, Ziegler D, Pedley T. Seizures, syncope and their mimics
        In: Rowland L, ed. Merritt’s Neurology, 11th ed. New York: Lippincott Williams & Wilkins; 2005:13–20.

Syncope v GTCS
    After blackout                                Syncope                                 Generalised tonic
                                                                                           clonic seizure

Confusion/disorientation                  Rare;

Epileptic Seizures

The clinical manifestation of excessive
 and/or hypersynchronous, usually self-
 limited abnormal activity of neurones of
 the cerebral cortex

Generalised tonic clonic seizures

•   No relation to posture, uncommonly precipitated

•   Rigid collapse with LOC: bilateral posturing/rigidity of limbs and
    trunk – tonic phase ~20-30 seconds

•   Strong rhythmical jerking of limbs – often more apparent in arms
    than legs – clonic phase ~1-3mins, gradually slows before stopping

•   Deep unconsciousness immediately after jerking stops ~ 30
    seconds+

•   Gradual recovery of orientation characterised by confusion,
    amnesia for early period of recovery, agitation - >5minutes

Syncope

Abrupt, transient and self-limiting loss of
 consciousness associated with loss of
 postural tone, caused by a sudden fall in
 cerebral perfusion

Convulsive syncope
• Limp collapse with LOC
   –   Motor features usually delayed by seconds
   –   Brief tonic phase
   –   Brief myoclonic phase
   –   Brief clonic phase

• Rapid recovery of consciousness

• No amnesia for early stage of recovery (NB
  sometimes in elderly)

• May be precipitated, related to posture, associated with
  prodrome but may not.

Other neurological mimics of syncope

Epileptic
• Tonic seizures
• Atonic seizures

Psychogenic non-epileptic attacks

Transient CSF obstruction

Posterior circulation TIAs

Meniere’s disease

Cataplexy

3rd Ventricle

Posterior Fossa

Craniocervical
Junction

Neurological mimics of epilepsy
Intermittent CSF obstruction
Causes: Third ventricular tumours, posterior fossa tumours, Chiari
  malformations
Symptoms: Headache associated with cough, brainstem symptoms: vertigo,
  ataxia, drop attacks

Posterior circulation TIAs
Drop attacks may occur in isolation
May be independent history of attacks of ataxia, vertigo, unilateral, bilateral
   upper limb dysaesthesia +/- occipital headache

Meniere’s disease:
Episodic fluctuating rotational vertigo, deafness tinnitus, aural fullness;
Severe rotational vertigo can cause drop attacks.

Cataplexy
• Occurs as part of symptom complex of narcolepsy:
  excessive daytime sleepiness, sleep paralysis,
  cataplexy, hypnagogic hallucinosis

• Cataplexy: episodes of loss of postural tone triggered by
  emotion-laden situations, consciousness preserved,

The appropriate use of
               investigations
•   Detailed clinical evaluation - repeated
•   Video – detailed review
•   ECG
•   U&Es, glucose (in acute situation)
•   Brain imaging

Only then…
• Routine and sleep EEG
• Long-term EEG monitoring
• Tilt table

The problem with EEG

‘routine interictal EEG is one of the most
abused investigations in clinical medicine
and is unquestionably responsible for
great human suffering.’

                               David Chadwick 1990

Electroencephalography
•   1929 - EEG first recorded form humans in by Hans Berger

•   1957 - Gastaut demonstrated that EEG can differentiate syncope
    from epilepsy
•   Interictal epileptic discharges associated with clinical diagnosis of
    epilepsy

•   BUT only 29-55% with diagnosis of epilepsy have abnormal routine
    EEG, 0.5% of 17-24 year olds without epilepsy have interictal
    epileptic discharge

•   Some interictal abnormalities aid in prediction of further seizures3 but
    not all

•   Abnormalities increase in elderly and with learning disability and in
    chronic psychoses

Fp2-AVG
Fp1-AVG
F8-AVG
F4-AVG
Fz-AVG
F3-AVG
F7-AVG
T4-AVG
C4-AVG
Cz-AVG
C3-AVG
T3-AVG
T6-AVG
P4-AVG
Pz-AVG
P3-AVG
T5-AVG
O2-AVG
O1-AVG

                  100 µV
          1 sec

Electroencephalography
•   Appropriate use of EEG in epilepsy
    – To stratify the risk of further epileptic seizures after a single epileptic
      seizure
    – To classify epilepsy
    – When no witness account
    – When reviewing diagnosis
    – Diagnosis of non-convulsive status epilepticus and convulsive status
      epilepticus

•   Use routine EEG +/- natural drowsiness

•   Long-term EEG if routine EEG doesn’t provide all answers
    – Ambulatory EEG for interictal epileptic discharges: sensitivity 80%
    – In-patient video-EEG: event capture rate 70%

Cardiac effects of epileptic seizures
                 - and vice versa
•   Ictal sinus tachycardia in greater than 90% of seizures:
     – Keilson et al Arch Neurol 1989: 46: 1169-70

•   Ictal bradycardia or asystole in less than 1% of cases
     – Rocamora et al: Epilepsia: 2003:44: 179-185
     – Scheule et al: Neurology: 2007: 69: 434-441
     – Unclear whether pacemaker insertion of benefit

•   Cardiac arrhythmias documented in SUDEP
     – Reduced heart rate variability documented in patients with SUDEP
       compared to control group – heart rate variability reduced in refractory
       temporal lobe epilepsy: Ansakorpi et al: JNNP: 2002: 72: 26-30

•   EEG/ECG evidence of hypoperfusion induced epileptic seizures

William Gowers   Hans Berger   Henri Gastaut