Clinical Features of Grand Mal Seizures

Key Clinical Features During the Tonic Phase

The European Society of Cardiology notes that sustained muscle rigidity with extension of extremities is a characteristic of the tonic phase of a grand mal seizure 1, 2
Tonic posture that often precedes the fall, unlike in syncope where collapse is typically flaccid, is observed in grand mal seizures 3
Patients may fall stiffly, described as "keeling over like a falling log", during a grand mal seizure 1, 2
Eyes typically remain open during the tonic phase of a grand mal seizure 3
Face may become cyanotic (blue) due to respiratory arrest during a grand mal seizure 4
Pupillary changes may include dilation or poor responsiveness in patients experiencing a grand mal seizure 5
Eye deviation may be present as a subtle sign of a grand mal seizure 6

Irregular respiratory patterns or temporary cessation of breathing may occur during a grand mal seizure 6
Initial "ictal cry" may occur at onset of a grand mal seizure due to air being forcefully expelled through partially closed vocal cords 3
Stertorous (snoring) breathing may develop during a grand mal seizure 3

The tonic phase of a grand mal seizure typically lasts 10-20 seconds before transitioning to the clonic phase 4
Movements begin at the onset of unconsciousness in grand mal seizures, unlike in syncope where movements typically start after loss of consciousness 3, 4

Increased salivation may lead to drooling or frothing at the mouth in patients experiencing a grand mal seizure 6
Pupillary dilation may occur in patients experiencing a grand mal seizure 5
Complete loss of consciousness coinciding with the onset of tonic movements is a characteristic of grand mal seizures 4
Possible tongue biting, typically on the lateral sides of the tongue, may occur during a grand mal seizure 4

In grand mal seizures, tonic movements begin at the onset of unconsciousness, while in syncope, movements (if present) start after loss of consciousness 4
Tonic movements in seizures are usually prolonged and symmetrical, unlike the brief, asymmetrical movements seen in syncope 4
The presence of an "ictal cry" strongly suggests epilepsy rather than syncope or other causes of loss of consciousness 3
Tongue biting on the lateral side is more indicative of seizures, while tip biting (if it occurs) is more common in syncope 4

Subtle or subclinical seizures may manifest only as eye deviation, irregular respiratory patterns, or drooling, making them easy to miss without careful observation 6
Hypoglycemia may precipitate seizures or posturing and should be considered in cases presenting with seizure-like activity 5
In the peri-ictal state, pupillary signs and consciousness level may be misleading when assessing for raised intracranial pressure 5
EEG monitoring is essential for confirming the diagnosis in ambiguous cases, as clinical features alone may sometimes be insufficient 7

A patient experiencing a tonic-clonic seizure does not respond to pain stimulus because they are in a state of complete loss of consciousness with sustained muscle rigidity and cannot process or react to external stimuli during the ictal phase, as stated by the European Society of Cardiology 8
Absence of awareness or ability to process sensory input occurs during tonic-clonic seizures, as consciousness is completely lost rather than merely altered, according to the European Heart Association 8

The lack of response to pain during a tonic-clonic seizure helps differentiate it from other conditions, such as syncope, where patients may exhibit brief myoclonic movements but these occur after loss of consciousness and are typically asynchronous and limited in scope, as noted by the European Society of Cardiology 8
Unconsciousness without any movement makes epilepsy unlikely, but the presence of tonic posture with forceful extension of extremities is characteristic of seizures, as stated by the American Heart Association 8

Prolonged confusion or sleepiness lasting more than a few minutes after regaining consciousness points to epilepsy rather than syncope, according to the European Heart Association 8
During the post-ictal state, patients gradually regain consciousness and may begin responding to stimuli, but this occurs after the seizure has ended, as noted by the European Society of Cardiology 8