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PubMed This is a summary of 24 peer-reviewed journal articles Updated
Neurology · Focal Sensory Seizures

What Happens During Ambulatory or Inpatient Video EEG?

At a Glance

During ambulatory or inpatient video EEG, electrodes record brain waves while you stay at home or in a monitoring unit. Press the event button and log sensory symptoms; a normal EEG or an episode without visible scalp changes does not by itself rule out focal epilepsy.

In this answer

4 sections

01

Ambulatory vs. Inpatient Monitoring

02

Preparing for the Test: Safety, Medications, and Sleep

03

During the Test: Event Buttons and Symptom Logs

04

Interpreting the Results: What if My Usual Episode Is Not Recorded?

A prolonged EEG (electroencephalogram) is a test that continuously records your brain waves over one or more days. Its primary goal is to capture your brain’s electrical activity at the exact moment you experience a suspected sensory episode. Because routine, short EEGs often miss infrequent spells, prolonged monitoring increases the chance of recording an event. The setup involves cleaning your scalp and securing small electrodes with adhesive or paste [1] [2].

Ambulatory vs. Inpatient Monitoring

Your doctor will recommend either an ambulatory or an inpatient EEG based on how frequently your episodes occur and what safety protocols you require [3].

  • Ambulatory EEG (Home): You wear a small, portable recording device at home [4]. These tests typically last 24 to 72 hours, though some protocols last up to 4 days [5]. You remain in your natural environment, which allows for normal sleep and daily routines [6]. Ambulatory tests may or may not include a synchronized video camera in your home [4] [7]. If there is no video, the observations of a caregiver become especially important. Because you are at home, you must avoid environmental sources of electrical interference that can create artifact and ruin the recording [8].
  • Inpatient Video-EEG (Hospital): This takes place in a specialized Epilepsy Monitoring Unit (EMU) over several days [5]. You will be continuously recorded on video [9]. The environment is highly controlled, with staff who check on you and follow specific unit protocols to evaluate you and ensure your safety during an episode [9] [10]. Privacy arrangements for video monitoring vary by center.

Preparing for the Test: Safety, Medications, and Sleep

Safety is the most critical part of prolonged monitoring, especially if you are at home.

  • Medications and Sleep: You may have heard that doctors lower medications or restrict sleep to induce a seizure. While some specialized EMU protocols adjust medications or sleep to improve the chance of capturing an event, this carries serious risks, including severe seizure clusters or status epilepticus [11] [12] [13]. You must never stop your medication or restrict your sleep unless you have a specific, written plan from your neurology team [11] [14].
  • Home Safety Plan: If you are having an ambulatory test, you must follow the clinic’s safety rules. This generally means keeping the equipment dry (no showering or swimming) and avoiding driving, heights, or operating machinery. Ask your team for a clear rescue plan. Crucially, the event button on an ambulatory EEG only marks the recording—it does not call for medical help. You and your caregiver should call 911 (or your local emergency number) if a seizure lasts longer than 5 minutes, if you have repeated seizures without recovering in between, or if you experience breathing difficulty or serious injury.

During the Test: Event Buttons and Symptom Logs

Because focal sensory seizures cause subjective symptoms—like tingling, numbness, or a strange taste—the recording equipment cannot always detect when an episode starts. You and your caregiver must actively participate in documenting events.

  • The Event Button: You will be given a portable pushbutton. Press it the moment you feel your sensory symptoms begin [15]. If you cannot press it, a caregiver should do it for you. Mark the event only when it is safe to do so; never delay first aid to press the button.
  • The Symptom Log: Write down what happened in an event diary [15]. Describe your precise physical sensations (e.g., “tingling in left hand spreading up the arm”) rather than just writing “had a seizure” [16] [17]. A useful diary entry includes the start and end time, exact body location, awareness/responsiveness, triggers, and what a witness saw. These details—your semiology—help your doctor characterize the event and interpret the EEG recording [17].
  • Capturing Multiple Events: Recording more than one episode may be needed to increase diagnostic confidence, so continue logging every event [18].

Interpreting the Results: What if My Usual Episode Is Not Recorded?

A common fear is that the test will end before your typical episode occurs. If your habitual episode is not recorded, the test cannot directly link your specific symptoms to an EEG pattern [19]. However, the monitoring can still be useful: if abnormal brain waves between episodes (interictal discharges) are captured, this can still support an epilepsy diagnosis [6].

If you do experience an episode but the EEG does not show any changes, it does not mean your symptoms are imagined. Scalp EEGs can miss focal seizures because the electrical signal is too small, originates deep in the brain, is poorly synchronized, or is hidden by muscle movement (artifact) [20]. A normal interictal EEG also does not rule out focal epilepsy [21] [22].

Your neurologist will not rely on the EEG alone. They will combine the EEG results with your medical history, your symptom log, and potentially other specialized tests to determine your diagnosis and next steps [23] [24].

Common questions in this guide

How is home EEG different from inpatient video EEG?
An ambulatory EEG uses a portable recorder while you stay at home, usually for 24 to 72 hours, and video may or may not be included. Inpatient video EEG takes place in a hospital epilepsy monitoring unit, where staff can observe you continuously and follow safety protocols.
Should I stop my seizure medicine or sleep less before the test?
Do not stop antiseizure medicine or restrict your sleep unless your neurology team gives you a specific written plan. Some hospital monitoring protocols change medication or sleep, but these changes can cause serious seizures and require medical supervision.
What should I do when my sensory symptoms start?
Press the event button as soon as symptoms begin if it is safe to do so, or ask your caregiver to press it. Then record what you felt, when it started and stopped, and whether you remained aware; never delay first aid to mark an event.
What details belong in an EEG symptom diary?
Record the exact sensation and body location, such as tingling that spreads from a hand up the arm. Also note the start and end times, awareness or responsiveness, possible triggers, and what a witness observed.
What if my usual episode is not captured or the EEG looks normal?
If your typical episode is not recorded, the test cannot directly compare your symptoms with an EEG pattern, although abnormal brain waves between episodes may still support an epilepsy diagnosis. A normal EEG or an episode without visible scalp changes does not rule out focal epilepsy, so your neurologist will also consider your history and symptom description.
When should I call for emergency help during an ambulatory EEG?
The event button only marks the recording and does not summon medical help. Follow your written rescue plan and call 911 or your local emergency number if a seizure lasts longer than five minutes, seizures repeat without recovery, breathing is difficult, or a serious injury occurs.

Questions For You

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Related questions

What Do EEG Results Mean in Focal Sensory Seizures? How Can You Tell Focal Sensory Seizures From Panic and FND? How Long Do Focal Sensory Seizures Last? Recovery Explained How Is the Best Medicine Chosen for Focal Sensory Seizures? Can Focal Sensory Seizures Cause Permanent Brain Damage?
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What Blood Tests Are Used for Focal Sensory Seizures? What Does Epilepsy-Protocol MRI Look For in Focal Epilepsy? When Should a Normal EEG Be Repeated for Focal Seizures? How Long Until Focal Sensory Seizure Medications Work? Can Partial Sensory Epilepsy Cause Nocturnal Seizures? Why You Can Stay Aware During a Focal Sensory Seizure? What Are Focal Sensory Seizure Medication Side Effects? What If Medication Partly Controls Focal Sensory Seizures? How Are Focal Sensory Seizures Diagnosed? EEG and MRI What Causes Focal Sensory Epilepsy? Genes or Brain Lesions? What to Record in a Focal Sensory Seizure Diary or Video? Can Focal Sensory Seizures Become Full-Body Seizures? Does One Focal Sensory Seizure Mean I Have Epilepsy? Are Focal Epilepsy Meds Safe in Pregnancy & Breastfeeding?

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Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Will this be an ambulatory study at home, or an inpatient admission to the epilepsy monitoring unit, and will video be included?
  2. 2.What are your exact written instructions regarding my antiseizure medications and sleep schedule before and during the test?
  3. 3.What are my specific activity restrictions during the test, such as driving, working, or showering?
  4. 4.What is my individualized safety and rescue plan if a severe or prolonged seizure occurs while I am monitoring at home?
  5. 5.If my typical sensory episode is not captured during this test, what will our next diagnostic steps be?

References

References (24)
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    Technical Tips: Preventing Electrode-Induced Skin Injuries During Prolonged Ambulatory Electroencephalography Monitoring.

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    A Prospective Randomized Controlled Trial: Alternative Approach to EEG Application to Reduce Electrode-induced Skin Injury among Ambulatory EEG Patients.

    Ouchida S, Nikpour A, Fairbrother G

    The Neurodiagnostic journal 2022; (62(1)):37-51 doi:10.1080/21646821.2022.2043086.

    PMID: 35320692
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    Diagnostic yield and limitations of in-hospital documentation in patients with epilepsy.

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    Minimum Technical Requirements for Performing Ambulatory EEG.

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    Ambulatory EEG to Classify the Epilepsy Syndrome.

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This page explains what may happen during ambulatory or inpatient video EEG for educational purposes and does not replace medical advice. Follow your neurology team's written instructions for medications, activities, sleep, and emergency care.