investigations in neurology powerpoint presentation

neurology

1. Neurologic diagnostic tests: with the use of ultrasound and electrophysiological methods P resented by Kaliparambu Haris Aftab (M2051) DEPARTMENT OF NEUROLOGY

2. Ultrasonography (USG) in neurology provides real-time imaging of nervous system structures. Particularly useful in neonatal care for conditions like intraventricular hemorrhage and hydrocephalus. Transcranial Doppler ultrasound (TCD) aids in diagnosing conditions like vasospasm post-subarachnoid hemorrhage. USG visualizes peripheral nerves, aiding in the diagnosis of entrapment syndromes and traumatic injuries. Its portability allows for bedside assessments, reducing the need for patient transport. USG lacks ionizing radiation, making it safer for frequent use, especially in pediatric patients. While not as detailed as MRI or CT scans, USG's immediacy and accessibility are invaluable in critical situations. ULTRASONGRAPHY IN NEUROLOGY!

3. Carotid Doppler ultrasonography- INTRODUCTION Carotid Doppler ultrasonography is a popular tool for evaluating atherosclerosis of the carotid artery. Its two-dimensional gray scale can be used for measuring the intima-media thickness, which is very good biomarker for atherosclerosis and can aid in plaque characterization. The plaque morphology is related to the risk of stroke. The ulceration of plaque is also known as one of the strong predictors of future embolic event risk. Color Doppler ultrasonography and pulse Doppler ultrasonography have been used for detecting carotid artery stenosis.

4. Carotid Doppler ultrasonography- TECHNIQUE Carotid Doppler ultrasound involves placing a transducer on the neck to emit high-frequency sound waves that bounce off the carotid arteries. These waves create images of blood flow, detecting any narrowing (stenosis), blockages, or plaques in the arteries supplying blood to the brain. The patient typically lies on their back with their head turned slightly away from the side being examined. Gel is applied to the skin to enhance sound wave transmission . The transducer is then moved over the neck in various angles to obtain comprehensive images. Doppler technology assesses blood flow velocity and direction, aiding in diagnosis.

5. Carotid Doppler ultrasonography- DIAGNOSTIC CRITERIA ABBREVIATIONS- ICA , internal carotid artery; PSV , peak systolic velocity; EDV , end diastolic velocity; CCA , common carotid artery

6. TRANCRANIAL DOPPLER ULTRASOUND Transcranial ultrasound (TUS) employs a handheld transducer placed on the scalp to emit sound waves, which penetrate the skull to visualize brain structures. It's often used to assess blood flow in the intracranial vessels, aiding in conditions like stroke, subarachnoid hemorrhage, and vasospasm. During the procedure, the patient typically lies comfortably, and a coupling gel is applied to the scalp to facilitate sound wave transmission. The transducer is moved across specific areas of the skull to obtain images, with Doppler technology used to assess blood flow velocity and direction. TUS provides real-time information, aiding in timely diagnosis and management of neurological conditions.

7. ELECTRODIAGNOSTIC STUDIES IN NEUROLOGY: Electrophysiological brain imaging measures neuronal electrical activity, offering real-time insight into brain function . Techniques like EEG provide high temporal resolution, aiding research in cognition, behavior, and clinical diagnosis of neurological disorders. These methods are non-invasive, portable, and versatile, often integrated with other imaging techniques for comprehensive analysis. They enable real-time feedback applications like neurofeedback training and brain-computer interfaces.

8. ELECTROENCEPHALOGRAPHY(EEG) Electroencephalography (EEG) records brain electrical activity via scalp electrodes. Normal EEG patterns vary by age and arousal level. In adults, alpha (8-13 Hz) and beta (>13 Hz) rhythms are typical at rest, with alpha attenuating upon eye opening. Drowsiness shows reduced alpha, while light sleep exhibits theta (4-7 Hz) and delta (<4 Hz) waves. Digital systems enhance EEG analysis, allowing various formats and detailed manipulation. Activation procedures provoke abnormalities, including hyperventilation and photic stimulation. EEG, relatively cheap, aids clinical management in diverse scenarios. Its wide use, especially with digital technology, facilitates detailed analysis and detection of abnormalities for clinical purposes.

9. EEG IN EPILEPSY EEG parameters indicating epilepsy include abnormal spikes, sharp waves, or spike-and-wave complexes, termed interictal epileptiform discharges (IEDs). These abnormalities occur between seizures and can manifest as focal or generalized patterns. Seizure activity captured during EEG recordings aids diagnosis and treatment planning. Additionally, assessing background brain activity, activation procedures, and employing quantitative EEG analysis offer valuable insights. EEG serves as a crucial diagnostic tool, aiding in differentiating epileptic syndromes and guiding treatment decisions. However , interpretation should consider clinical history and other diagnostic tests for accuracy in epilepsy diagnosis and management.

10. EEG IN COMA In coma, the background activity is often significantly altered. Instead of the typical rhythmic activity seen in wakefulness or sleep, there may be low-voltage or even flat EEG patterns . Presence of Waves Delta Waves : These slow waves (0.5 to 4 Hz) are often seen in coma, particularly in deeper stages. Theta Waves : These slower waves (4 to 8 Hz) might also be present, especially in lighter stages of coma or during transition states . Lack of reactivity to external stimuli is a hallmark of coma. In a normal awake state, the EEG typically shows changes in response to sensory stimuli (such as flashing lights or auditory cues). In coma, there may be no such changes . Burst Suppression - This pattern consists of bursts of electrical activity separated by periods of electrical silence. It's often seen in deep coma or in patients with severe brain injury A typical slow-wave pattern in coma is shown with high-voltage semirhythmic delta waves.

11. EEG IN OTHER NEUROLOGICAL DISORDERS Focal or lateralized periodic slow-wave complexes, potentially with a sharpened outline, suggest herpes simplex encephalitis in acute encephalopathy. Periodic lateralizing epileptiform discharges (PLEDs) are common in acute hemispheric pathology like hematoma, abscess, or rapidly expanding tumors. EEG findings in dementia are typically nonspecific, making it difficult to differentiate between causes of cognitive decline. Periodic complexes, occurring with regular repetition, may indicate Creutzfeldt-Jakob disease or subacute sclerosing panencephalitis . In most dementia cases, EEG either appears normal or shows diffuse slowing, making it inadequate to determine dementia or pseudodementia solely based on EEG findings. Periodic complexes occurring once every second in a patient with Creutzfeldt-Jakob disease

12. ELECTROMYOGRAPHY The pattern of electrical activity in muscle (i.e., the electromyogram [EMG]), both at rest and during activity, may be recorded from a needle electrode inserted into the muscle. The nature and pattern of abnormalities relate to disorders at different levels of the motor unit. The principle of generation of the EMG signal . ( a) the structure of the neuro -muscular system. ( b) the schematic of the EMG signal transduction in the nerve and muscle system.

13. ELECTROMYOGRAPHY Abnormal spontaneous activity is a common feature in neuromuscular disorders, particularly those involving denervation or inflammatory changes in muscles. Fibrillation potentials and positive sharp waves, indicating muscle fiber irritability, are often found in denervated muscle tissue. Fasciculation potentials, reflecting the spontaneous activity of individual motor units, are characteristic of slowly progressive neuropathic disorders like amyotrophic lateral sclerosis (ALS). Myotonic discharges, marked by high-frequency potentials from single muscle fibers with fluctuating amplitude and frequency, are typical of myotonic disorders such as myotonic dystrophy. Parameters for these discharges include duration, amplitude, and waveform characteristics. Myopathic muscle often exhibits an increased incidence of small, short-duration, polyphasic motor unit action potentials and excessive recruitment of motor units for a given level of voluntary activity. Electromyography (EMG) is vital for distinguishing between neurogenic and myopathic disorders by assessing muscle pattern. EMG findings also offer insights into the severity and progression of neuromuscular disorders, assisting in prognosis and treatment planning.

14. ELECTROMYOGRAPHY A. Spontaneous fibrillation potentials and positive sharp waves. B . Complex repetitive discharges recorded in partially denervated muscle at rest. C . Normal triphasic motor unit action potential. D . Small, short-duration, polyphasic motor unit action potential such as is commonly encountered in myopathic disorders . E . Long-duration polyphasic motor unit action potential such as may be seen in neuropathic disorders.

15. NERVE CONDUCTION STUDIES Nerve conduction studies (NCS) are a type of electrodiagnostic test used to evaluate the function of peripheral nerves Principle : NCS measure the speed and strength of electrical signals as they travel along peripheral nerves. Electrodes are placed on the skin to stimulate the nerve with a mild electrical impulse, and other electrodes detect the response downstream . INDICATIONS: Peripheral neuropathy : Slowed conduction velocity, reduced amplitude of response, prolonged distal latency. Carpal tunnel syndrome : Reduced sensory and/or motor conduction velocities across the wrist, with prolonged distal latency. Radial nerve dysfunction Ulnar nerve dysfunction Guillain-Barré syndrome : Initially, there may be a reduction in conduction velocities, followed by complete conduction block in severe cases. Charcot-Marie-Tooth disease : Gradual reduction in nerve conduction velocities over time .

16. BIBLIOGRAPHY 1. Harrison's Neurology in Clinical Medicine 2. PubMed: EEG in the diagnosis, classification, and management of patients with epilepsy 3. Radiological Society of North America 4. Electrodiagnosis in Diseases of Nerve and Muscle: Principles and Practice by Jun Kimura 5. American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM)

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