## Definition and Clinical Features **Key Point:** Atonic seizures (also called drop attacks or akinetic seizures) are characterized by a sudden, complete loss of muscle tone lasting 1–2 seconds, resulting in the patient collapsing to the ground. Consciousness is retained or recovered immediately. ## Seizure Type Comparison | Seizure Type | Muscle Tone Change | Duration | Consciousness | EEG Pattern | | --- | --- | --- | --- | --- | | **Atonic** | Sudden loss (flaccid) | 1–2 sec | Immediate recovery | Generalized slow wave | | **Tonic** | Sustained rigidity | 10–20 sec | Impaired | Generalized fast activity | | **Myoclonic** | Brief jerks | <1 sec | Preserved | Generalized polyspike-wave | | **Absence** | None (staring) | 5–20 sec | Impaired | 3 Hz spike-and-wave | ## Clinical Presentation **High-Yield:** Atonic seizures are most common in childhood epilepsy syndromes, particularly Lennox-Gastaut syndrome. Patients often sustain head and facial injuries due to sudden falls without warning. The seizure is brief but devastating functionally. ## Mechanism Atonic seizures involve sudden suppression of motor neuron activity, leading to flaccid paralysis. The exact mechanism is not fully understood but likely involves inhibitory neurotransmission (GABA) overwhelming excitatory drive. ## Clinical Pearl **Warning:** Do not confuse atonic seizures with tonic seizures. In tonic seizures, muscles become RIGID and the patient is stiff; in atonic seizures, muscles become FLACCID and the patient collapses. Atonic seizures are also called "drop attacks" because the patient literally drops to the ground.
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