Fainting and Loss of Consciousness: Causes, Symptoms, and First Aid

What is fainting and loss of consciousness?

Fainting, or syncope, is a sudden, brief loss of consciousness caused by a temporary decrease in blood flow to the brain. This is a fairly common phenomenon that in most cases poses no serious threat to health. However, loss of consciousness can also be a symptom of more serious underlying conditions, including neurological disorders, cardiovascular problems, or metabolic disturbances. Understanding potential causes and knowing how to provide first aid are vital.

Neurological causes of impaired consciousness

Although many fainting episodes are benign in nature, some conditions accompanied by impaired consciousness may be associated with serious neurological diseases that require thorough diagnosis and treatment.

Migraine and its unusual manifestations

• SMART syndrome (Stroke-like Migraine Attacks After Radiation Therapy): This is a rare, delayed complication after cranial radiation therapy that can manifest years or even decades after irradiation. Symptoms include severe headaches, stroke-like episodes (e.g., hemiparesis, aphasia), seizures, and confusion [2, 4]. Brain MRI reveals temporary, reversible cortical changes in previously irradiated areas. Treatment may include high doses of corticosteroids [4].
• Olfactory hallucinations: In rare cases, migraine can be accompanied by an unusual aura in the form of olfactory hallucinations (phantosmia), when a person perceives unpleasant odors (such as rot or burning plastic) without a real source. Such symptoms can precede a severe headache and, as shown in one case, lead to significant weight loss due to loss of appetite [3].
• Chronic migraine and its treatment: Chronic migraine is a disabling neurological disorder that can be refractory to standard treatments. In one case, a 76-year-old woman with a 40-year history of treatment-resistant chronic migraine experienced complete resolution of migraines following focused ultrasound thalamotomy (a procedure typically used to treat essential tremor) [5].
• Autonomic nervous system dysfunction: Migraine is often associated with other autonomic nervous system dysfunction syndromes, such as postural orthostatic tachycardia syndrome (POTS), chronic fatigue, and "brain fog," which can affect mental clarity and overall well-being [8].

Genetic and systemic factors

In addition to neurological causes, there are genetic and systemic factors that can lead to impaired consciousness or conditions mimicking serious neurological events.

• Genetic mutations: Variants of the ATP1A2 gene, which encodes the α2-subunit of Na+/K+-ATPase, are associated with a wide range of clinical manifestations, including familial hemiplegic migraine type 2 (FHM2), epilepsy, and intellectual disability. In one case, a 22-year-old woman with such a gene variant experienced prolonged depressed consciousness and prominent brain edema. Early genetic testing allowed for the identification of the cause and the initiation of targeted therapy with memantine, resulting in a reduced frequency of migraines and seizures [1].
• Vitamin B12 deficiency: Vitamin B12 deficiency is a common condition that can cause cognitive impairment, polyneuropathy, and subacute combined degeneration of the spinal cord. In rare cases, B12 deficiency can present with extrapyramidal movement disorders, such as chorea. Timely diagnosis and vitamin B12 replacement therapy can lead to complete resolution of symptoms [6].

When to see a doctor?

Although many fainting episodes are not dangerous, immediate medical attention is necessary in the following cases:

• The loss of consciousness is accompanied by an injury.
• The fainting lasts longer than a few minutes.
• The person does not regain consciousness after fainting.
• Fainting is accompanied by seizures, chest pain, shortness of breath, severe headache, numbness, or weakness in the limbs.
• Fainting episodes recur.
• Loss of consciousness occurs in an elderly person or someone with known heart disease, diabetes, or other chronic conditions.

First aid for fainting

If you witness someone fainting, follow these recommendations:

1. Lay the person down: Gently lay the person flat on their back.
2. Elevate the legs: Raise the victim's legs 30-45 cm above head level to improve blood flow to the brain.
3. Loosen clothing: Unbutton collars and belts, and loosen any tight clothing to facilitate breathing.
4. Provide fresh air: Open windows if you are indoors, or ask people to step back to ensure an influx of fresh air.
5. Revive the person: You can tap their cheeks, splash water on their face, or let them inhale ammonia spirits (but do not hold it too close to the nose).
6. Do not give anything to drink: Do not attempt to give the person anything to drink or eat until they have fully regained consciousness.
7. Call an ambulance: If consciousness is not restored within 1-2 minutes, or if there are other alarming symptoms (e.g., seizures, difficulty breathing, chest pain), call an ambulance immediately.

Diagnosis and treatment

Diagnosis of the causes of loss of consciousness begins with a thorough medical history and physical examination. Depending on the suspected cause, the following tests may be ordered:

• Laboratory tests: Complete blood count, comprehensive metabolic panel, glucose levels, electrolytes, vitamin B12 [6], vitamin D3 [3], and other markers.
• Instrumental methods: Electrocardiography (ECG) to assess heart function, electroencephalography (EEG) to detect epileptic activity [2, 3], brain magnetic resonance imaging (MRI) to identify structural changes such as edema or ischemic lesions [1, 2, 3].
• Genetic testing: In cases of suspected hereditary disorders, such as ATP1A2 gene variants, genetic testing may be recommended for accurate diagnosis and selection of targeted therapy [1].

Treatment aims to address the underlying cause. This may include medication therapy (e.g., memantine for genetic mutations [1], corticosteroids for SMART syndrome [4], vitamin B12 replacement therapy [6]), lifestyle modifications, or, in rare cases, surgical interventions (e.g., thalamotomy for refractory migraine [5], endovascular stenting for pelvic venous disorders [8]).

Sources

• [1] Prolonged coma and cerebral oedema in a patient with an ATP1A2 variant. (Practical Neurology, 2026) https://pubmed.ncbi.nlm.nih.gov/41290403/
• [2] Stroke-Like Migraine Attacks After Radiation Therapy (SMART) Syndrome: A Diagnostic Challenge a Decade After Cranial Irradiation. (Cureus, 2025) https://pubmed.ncbi.nlm.nih.gov/41497923/
• [3] Olfactory Hallucinations Leading to Weight Loss in a Patient with Migraine. (Archives of Neuropsychiatry, 2026) https://pubmed.ncbi.nlm.nih.gov/41777509/
• [4] Stroke-like migraine attacks after radiation therapy (SMART) syndrome: a study in diagnosis, treatment and outcome. (BMJ Case Reports, 2026) https://pubmed.ncbi.nlm.nih.gov/41991235/
• [5] Resolution of chronic refractory migraine and development of burning mouth syndrome after focused ultrasound thalamotomy: illustrative case. (Journal of Neurosurgery: Case Lessons, 2026) https://pubmed.ncbi.nlm.nih.gov/42184431/
• [6] Case Report: Reversible chorea arising from severe vitamin B12 deficiency due to autoimmune gastritis: a comprehensive case study. (Frontiers in Nutrition, 2025) https://pubmed.ncbi.nlm.nih.gov/40917091/
• [8] Case Report: Neuropsychiatric improvement after treatment of pelvic venous disorder in a multisyndromic patient. (Frontiers in Cardiovascular Medicine, 2025) https://pubmed.ncbi.nlm.nih.gov/41602336/

The information provided in this article is for reference purposes only and cannot replace professional medical advice. Always consult a qualified specialist for diagnosis and treatment.