Are there seizure types that are unilateral or confined to a single limb?

Yes, Focal Seizures Can Be Unilateral or Limited to One Limb

Focal seizures are characterized by abnormal electrical activity restricted to one hemisphere of the brain and can manifest as jerking movements confined to a single extremity or one side of the body. 1

Clinical Presentation of Unilateral/Single-Limb Seizures

Motor Manifestations

• Focal motor seizures can present as jerking of only one extremity or one side of the body, distinguishing them from generalized seizures that affect both sides simultaneously 1
• Simple partial seizures without impairment of consciousness may include focal motor or somatosensory phenomena affecting a single body part 2
• Movements restricted to one limb or one side strongly suggest epilepsy rather than syncope, particularly when they begin before the fall 3

Epilepsia Partialis Continua (EPC)

• A specific subtype exists called epilepsia partialis continua, defined as continuous focal jerking of a body part, usually localized to a distal limb, occurring over hours, days, or even years 4
• EPC represents continuous muscle jerks of cortical origin and is most commonly seen in Rasmussen's syndrome (19% of cases) and cerebrovascular disease (14% of cases) 4

Key Diagnostic Features

Distinguishing from Generalized Seizures

• Focal seizures arise within networks of a single cerebral hemisphere and may remain localized or become more widely distributed 5, 6
• The hallmark is onset from a portion of one cerebral hemisphere, indicated by focal spikes or sharp waves on EEG 2
• Movements beginning before the fall and being partial or one-sided are characteristic of epilepsy 3

Clinical Classification

• Focal aware seizures maintain consciousness while exhibiting unilateral motor symptoms 7
• Simple partial seizures can occur without impairment of consciousness and include focal motor phenomena 2
• These seizures may progress to complex partial seizures with impaired awareness or secondarily generalize to affect both hemispheres 2

Important Clinical Pitfalls

EEG Limitations

• A normal routine EEG cannot rule out partial seizures in patients with episodes that sound clinically consistent with focal seizures 2
• Only 22% of EPC patients showed focal epileptiform scalp EEG abnormalities, despite clear clinical focal seizures 4

Bilateral Foci Consideration

• Approximately 15% of patients with temporolimbic epilepsy have concordance less than 70%, meaning they may have bilateral foci despite predominantly unilateral seizures 8
• Recording 5 concordant seizures from one side implies a 95% chance of at least 90% concordance to that hemisphere 8

Neuroimaging Necessity

• MRI or CT is indicated in essentially any child with partial seizures to identify underlying structural causes 2
• Lesions on imaging are found in 56% of cases, with half showing predominant cortical involvement 4

Emergency Management Considerations

When witnessing a focal seizure affecting one limb:

• Activate EMS for first-time seizures, seizures lasting >5 minutes, or seizures with traumatic injuries 1
• Help the person to the ground, place them on their side in recovery position, and clear the surrounding area 1
• Stay with the person throughout the seizure and postictal period 1