Electroencephalography — MCQs
Burst suppression on EEG is seen in
A 42-year-old female executive is referred to the sleep clinic with jaw pain. She complains that after she arrives home at night around 10 pm she frequently drinks 3-4 gin and tonics to help quiet her mind.’ She wakes up the next morning around 3am to read the international stock market news, at which point she states her teeth ache an unbearable amount. A study is performed on the patient and it is noted that she grinds her teeth and mutters during roughly half of her sleep. Which of the following would you expect to see on her EEG and at which stage of sleep would you expect her jaw pain to be caused?
In narcolepsy, the polysomnographic recording typically shows which of the following patterns?
Alpha wave on EEG represents -
What do motor evoked potentials primarily assess?
Berger waves (alpha waves) of EEG have a rhythm of how many Hz?
Which wave is seen in the given EEG recording?
A polysomnography is performed on a patient. Based on the provided EEG, EOG, and EMG findings, which stage of sleep is indicated? (Image: img-182.jpeg)
Which of the following cells in the brain are responsible for handling information regarding ability to read the slide below? (Recent NEET Pattern 2016-17)
Which lipoprotein has the highest concentration of endogenous triglycerides?
Electroencephalography Indian Medical PG Practice Questions and MCQs
Question 1: Burst suppression on EEG is seen in
- A. Epilepsy
- B. Prions disease
- C. SSPE (Correct Answer)
- D. Herpes
Explanation: ***SSPE*** - **Subacute sclerosing panencephalitis (SSPE)** is a rare, fatal, and chronic progressive encephalitis caused by persistent measles virus infection, often presenting with **burst suppression** on EEG. - **Burst suppression** EEG patterns are characterized by periods of high-amplitude electrical activity alternating with periods of profound suppression or inactivity, reflecting severe global brain dysfunction. *Epilepsy* - **Epilepsy** typically presents with various EEG patterns such as **spikes, sharp waves, or spike-and-wave complexes**, reflecting hyperexcitable neuronal networks [2]. - While prolonged seizures (status epilepticus) can lead to a suppressed EEG, classic burst suppression is not a hallmark of typical epileptic seizures [1]. *Prions disease* - **Prion diseases**, such as Creutzfeldt-Jakob disease (CJD), often show characteristic EEG abnormalities like **periodic sharp wave complexes** or generalized slowing. - **Burst suppression** is not a typical or specific finding in prion diseases, although non-specific slowing or background disruption can occur in advanced stages. *Herpes* - **Herpes simplex encephalitis (HSE)** typically causes **focal abnormalities** like periodic lateralizing epileptiform discharges (PLEDs) or slowing over the temporal lobes on EEG. - While HSE can lead to severe brain damage and generalized slowing, **burst suppression** is not a characteristic EEG finding.
Question 2: A 42-year-old female executive is referred to the sleep clinic with jaw pain. She complains that after she arrives home at night around 10 pm she frequently drinks 3-4 gin and tonics to help quiet her mind.’ She wakes up the next morning around 3am to read the international stock market news, at which point she states her teeth ache an unbearable amount. A study is performed on the patient and it is noted that she grinds her teeth and mutters during roughly half of her sleep. Which of the following would you expect to see on her EEG and at which stage of sleep would you expect her jaw pain to be caused?
- A. Alpha waves, N2
- B. Beta waves, N3
- C. Delta waves, N3
- D. Sleep spindles, N2 (Correct Answer)
Explanation: ***Sleep spindles, N2*** - The patient's presentation of teeth grinding (**bruxism**) and muttering during sleep, along with jaw pain, is characteristic of **parasomnias**, which often occur during **stage N2 sleep**. - **Sleep spindles** and **K-complexes** are defining EEG features of **N2 sleep**, indicating that the sleep study would likely show these patterns. *Alpha waves, N2* - **Alpha waves** are characteristic of a **relaxed, awake state** or the early stages of falling asleep (N1), not N2 sleep. - While the patient has jaw pain, its cause is linked to sleep behaviors occurring in more advanced sleep stages than N1. *Beta waves, N3* - **Beta waves** are typically seen during **active wakefulness** and **REM sleep**, not deep N3 sleep. - **N3 sleep** (slow-wave sleep) is characterized by **delta waves**, not beta waves. *Delta waves, N3* - Although **delta waves** are indeed characteristic of **N3 sleep** (deep sleep), the patient's symptoms of teeth grinding and muttering are more commonly associated with **N2 sleep** or arousal disorders, not typically the deepest stage of sleep. - Bruxism and muttering are generally not prominent features of undisturbed N3 sleep.
Question 3: In narcolepsy, the polysomnographic recording typically shows which of the following patterns?
- A. REM intrusion during inappropriate periods (Correct Answer)
- B. An absence of REM sleep in midcycle
- C. Extreme muscular relaxation
- D. Spike-and-wave EEG recording
Explanation: ***REM intrusion during inappropriate periods*** - In narcolepsy, the hallmark polysomnographic finding is **sleep-onset REM periods (SOREMPs)** - the occurrence of REM sleep within 15 minutes of sleep onset. - The **Multiple Sleep Latency Test (MSLT)** in narcolepsy typically shows **≥2 SOREMPs** along with a mean sleep latency of ≤8 minutes. - Clinically, this **REM sleep intrusion** manifests as **sudden, irresistible sleep attacks** during the day, **cataplexy** (sudden muscle weakness triggered by strong emotions), **sleep paralysis**, and **hypnagogic/hypnopompic hallucinations**. - These represent features of REM sleep (muscle atonia, dreams) occurring at inappropriate times. *An absence of REM sleep in midcycle* - This statement is incorrect as narcolepsy is characterized by an **abnormal presence and early onset of REM sleep**, not its absence. - Individuals with narcolepsy enter REM sleep much faster than normal (often within minutes rather than the typical 90 minutes). *Extreme muscular relaxation* - While **cataplexy** (present in Type 1 narcolepsy) involves sudden loss of muscle tone due to REM-related atonia during wakefulness, this is a clinical symptom rather than a continuous polysomnographic finding. - Polysomnography focuses on **sleep architecture** and the timing of **REM sleep onset**, not general muscle relaxation patterns. *Spike-and-wave EEG recording* - **Spike-and-wave patterns** on EEG are characteristic of **absence seizures** (a form of epilepsy), not narcolepsy. - Narcolepsy is a primary **sleep disorder** with distinct polysomnographic features related to **REM sleep dysregulation**, not epileptiform activity.
Question 4: Alpha wave on EEG represents -
- A. Awake and fully alert
- B. Awake with eyes open
- C. Awake with eyes closed with mind wandering (Correct Answer)
- D. Deep sleep
Explanation: ***Awake with eyes closed with mind wandering*** - **Alpha waves** are characteristic of a relaxed, wakeful state when the eyes are closed and the mind is not actively focusing on a task. - They typically have a frequency range of 8-13 Hz and are most prominent over the **occipital lobe**. *Awake and fully alert* - This state is primarily associated with **beta waves** (13-30 Hz) due to active mental engagement and processing. - Alpha waves tend to be attenuated or replaced by beta activity when an individual is fully alert and actively concentrating. *Awake with eyes open* - When a person's eyes are open while awake, **alpha waves** are usually suppressed or "blocked" by visual input and mental processing. - This is known as **alpha blocking** or desynchronization, and the EEG shifts towards lower amplitude, higher frequency beta waves. *Deep sleep* - **Deep sleep** (Stage N3, or slow-wave sleep) is characterized by high-amplitude, low-frequency **delta waves** (0.5-4 Hz). - Alpha waves are not a prominent feature of deep sleep; instead, they are suppressed.
Question 5: What do motor evoked potentials primarily assess?
- A. Central motor pathways (Correct Answer)
- B. Both central and peripheral motor pathways
- C. Muscle regeneration
- D. Peripheral motor pathways
Explanation: ***Central motor pathways*** - **Motor evoked potentials (MEPs)** are generated by electrical or magnetic stimulation of the **motor cortex** and primarily assess the integrity of **central motor pathways**, specifically the **corticospinal tracts**. - MEPs are the **gold standard** for monitoring **upper motor neuron** function during neurosurgical and spinal procedures. - The technique is most sensitive to dysfunction in the **brain and spinal cord** (central nervous system), making this their primary clinical utility. *Peripheral motor pathways* - While MEPs do eventually activate peripheral motor neurons to produce muscle responses, they are **not the primary tool** for assessing peripheral pathways. - **Nerve conduction studies (NCS)** and **electromyography (EMG)** are direct and more specific measures for evaluating peripheral motor nerve function. *Both central and peripheral motor pathways* - Although MEPs provide information about the entire motor pathway from cortex to muscle, their **primary diagnostic strength and clinical application** is in detecting dysfunction within the **central nervous system**. - The latency and amplitude of MEPs are most sensitive to **conduction abnormalities along the corticospinal tract**, not peripheral nerves. *Muscle regeneration* - MEPs do **not assess muscle regeneration** or intrinsic muscle health. - **Electromyography (EMG)** with needle examination and **muscle biopsy** are the appropriate methods to evaluate muscle regeneration and myopathic processes.
Question 6: Berger waves (alpha waves) of EEG have a rhythm of how many Hz?
- A. 0-4 Hz
- B. 4-7 Hz
- C. 8-13 Hz (Correct Answer)
- D. 13-30 Hz
Explanation: ***8-13 Hz*** - **Berger waves**, also known as **alpha waves**, are defined by their frequency range of **8 to 13 Hz** in the electroencephalogram (EEG). - These waves are typically observed when a person is in a relaxed, awake state with their eyes closed. *0-4 Hz* - This frequency range corresponds to **delta waves**, which are characteristic of deep sleep and certain brain pathologies. - Delta waves are much slower and have higher amplitude compared to alpha waves. *4-7 Hz* - This frequency range is associated with **theta waves**, commonly seen during light sleep, drowsiness, and some meditative states. - Theta waves are slower than alpha waves and indicate a state of reduced alertness. *13-30 Hz* - This frequency range represents **beta waves**, which are associated with active thinking, problem-solving, and alertness with open eyes. - Beta waves are faster and typically have lower amplitude than alpha waves.
Question 7: Which wave is seen in the given EEG recording?
- A. Alpha waves
- B. Beta waves
- C. Epsilon wave
- D. Delta waves (Correct Answer)
Explanation: ***Delta waves*** - The highlighted EEG activity shows **large amplitude, low-frequency waves** (typically 0.5-4 Hz), which are characteristic of delta waves. - Delta waves are normally associated with **deep sleep** (NREM stage 3) or **pathological conditions** in awake adults, indicating significant brain dysfunction. *Alpha waves* - Alpha waves have a frequency range of **8-13 Hz** and typically appear when an individual is in a relaxed, awake state with eyes closed. - The waves in the image are much slower and higher in amplitude than typical alpha waves. *Beta waves* - Beta waves are characterized by a higher frequency range of **14-30 Hz** and are associated with active thinking, alertness, and concentration. - The observed activity is significantly slower and higher in amplitude than beta waves. *Epsilon wave* - The term "epsilon wave" is not a standard classification for EEG brain waves in the context of normal or common pathological activity, unlike alpha, beta, theta, and delta waves. - In cardiology, "epsilon wave" refers to a specific finding on an ECG in **Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)**, not an EEG.
Question 8: A polysomnography is performed on a patient. Based on the provided EEG, EOG, and EMG findings, which stage of sleep is indicated? (Image: img-182.jpeg)
- A. NREM 1
- B. NREM 2 (Correct Answer)
- C. NREM 3
- D. REM
Explanation: ***NREM 2*** - This stage is characterized by the presence of **sleep spindles** (bursts of brain activity) and **K-complexes** (large, slow waves) on the EEG. - The EOG typically shows **no significant eye movement**, and the EMG registers **lower muscle tension** compared to wakefulness or NREM 1. *NREM 1* - This initial stage of sleep is marked by the appearance of **theta waves** on the EEG and a reduction in alpha wave activity. - The EOG often shows **slow, rolling eye movements**, and the EMG indicates slightly **reduced muscle tone** compared to the wake state. *NREM 3* - Often referred to as **deep sleep** or slow-wave sleep, this stage is characterized by a significant presence of **delta waves** (high amplitude, low frequency) on the EEG, comprising 20-50% of the epoch. - Eye movements are **minimal or absent** on EOG, and muscle tension on EMG is **lower** than in NREM 2 but still present. *REM* - This stage is distinguished by **rapid eye movements** (REMs) observed on the EOG and a characteristic **sawtooth pattern** or low-voltage, mixed-frequency activity on the EEG. - A key feature of REM sleep is **atonia** (paralysis of skeletal muscles), resulting in the **lowest muscle tone** on the EMG, often appearing as a flat line.
Question 9: Which of the following cells in the brain are responsible for handling information regarding ability to read the slide below? (Recent NEET Pattern 2016-17)
- A. Magnocellular cells
- B. Parvocellular cells (Correct Answer)
- C. Purkinje cells
- D. Pyramidal cells
Explanation: ***Parvocellular cells*** - **Parvocellular cells** (P-cells) are responsible for processing detailed visual information, including **color**, **form**, and fine **texture**. Reading the Ishihara test requires the ability to distinguish specific colors and fine patterns. - They have **small receptive fields** and transmit information about high spatial resolution and chromatic detail, crucial for tasks such as reading and recognizing fine visual cues. *Magnocellular cells* - **Magnocellular cells** (M-cells) are primarily involved in detecting **motion** and processing **low-spatial frequency information**, such as global shape and location. - They have **large receptive fields** and are not primarily responsible for detailed color or pattern discrimination needed for reading. *Purkinje cells* - **Purkinje cells** are a type of large, extensively branched neuron located in the **cerebellar cortex**. - Their primary function is motor coordination, balance, and motor learning, not visual processing or reading. *Pyramidal cells* - **Pyramidal cells** are excitatory neurons found in the cerebral cortex and hippocampus, characterized by their pyramidal-shaped cell bodies. - While they are involved in complex cognitive functions, including parts of visual perception, they are not the specific cells in the primary visual pathway responsible for initial processing of fine details and color as required for reading this type of visual test.
Question 10: Which lipoprotein has the highest concentration of endogenous triglycerides?
- A. Chylomicrons
- B. VLDL (Very-low-density lipoprotein) (Correct Answer)
- C. LDL (Low-density lipoprotein)
- D. HDL (High-density lipoprotein)
Explanation: **Explanation:** The core of this question lies in distinguishing between **exogenous** and **endogenous** lipid transport. **Why VLDL is correct:** VLDL (Very-low-density lipoprotein) is synthesized in the **liver**. Its primary physiological role is to transport **endogenous triglycerides** (lipids synthesized by the body) from the liver to peripheral tissues. It contains approximately 50-60% triglycerides by weight, making it the lipoprotein with the highest concentration of triglycerides of internal origin. **Why the other options are incorrect:** * **Chylomicrons:** While chylomicrons have the highest *overall* triglyceride content (85-90%), these are **exogenous** (dietary) triglycerides absorbed from the intestines. The question specifically asks for endogenous sources. * **LDL:** Known as the primary carrier of **cholesterol** to peripheral tissues. It is a metabolic byproduct of VLDL (via IDL) and has a low triglyceride concentration. * **HDL:** Known as "good cholesterol," it is involved in **reverse cholesterol transport** (carrying cholesterol from tissues back to the liver). It has the highest protein content and the lowest lipid content. **High-Yield Clinical Pearls for NEET-PG:** * **Apolipoprotein Marker:** B-100 is the characteristic apolipoprotein for VLDL and LDL, while B-48 is unique to Chylomicrons. * **Rate-limiting enzyme:** HMG-CoA reductase is the rate-limiting enzyme for endogenous cholesterol synthesis (target of Statins). * **Lipoprotein Lipase (LPL):** This enzyme, located on capillary endothelium, is responsible for clearing triglycerides from both Chylomicrons and VLDL. * **Friedewald Equation:** LDL = Total Cholesterol – HDL – (Triglycerides/5). Note: This is invalid if TG >400 mg/dL.
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