Neurology Flashcards
Describe the anatomy of common sites of nerve root compression (C6, C7, L5, S1)
Nerve root compression, also known as a radiculopathy, occurs when nerve roots exiting the spinal column are impinged or irritated by surrounding tissues such as bones, cartilage, muscles, or tendons. This condition can cause pain, weakness, or numbness in the areas served by the affected nerves. Here, I’ll describe the anatomy related to common sites of nerve root compression at the C6, C7, L5, and S1 levels.
Cervical Spine (C6 and C7)
1. C6 Nerve Root:
Location: The C6 nerve root exits the spinal column between the C5 and C6 vertebrae.
Structure Implicated: Commonly compressed by herniated discs, degenerative changes, or osteophyte formation at the C5-C6 vertebral level.
Clinical Presentation: Compression here can cause pain and weakness in the biceps and wrist extensors, and numbness or tingling that radiates down the thumb side of the forearm and into the thumb.
- C7 Nerve Root:
Location: The C7 nerve root exits between the C6 and C7 vertebrae.
Structure Implicated: Like C6, it is prone to compression from herniated discs or osteophytes at the C6-C7 level.
Clinical Presentation: Symptoms may include pain and weakness in the triceps and finger extensors, and numbness or tingling that extends down the middle finger.
Lumbar Spine (L5 and S1) - L5 Nerve Root:
Location: The L5 nerve root exits the spinal column between the L4 and L5 vertebrae.
Structure Implicated: Compression often occurs due to a herniated disc at the L4-L5 level, spondylolisthesis, or spinal stenosis.
Clinical Presentation: Impingement can lead to pain and weakness in the dorsiflexors of the foot (lifting the foot upwards), and numbness along the top of the foot and into the big toe. - S1 Nerve Root:
Location: The S1 nerve root exits between the L5 and S1 vertebrae.
Structure Implicated: Typically compressed by herniated discs at the L5-S1 level, spondylolisthesis, or spinal stenosis.
Clinical Presentation: Symptoms include pain and weakness in the plantar flexors of the foot (pushing the foot downwards), and numbness or tingling that may radiate along the outer side of the foot and heel.
Common Compression Mechanisms:
Herniated Discs: Nucleus pulposus material can protrude through tears in the annulus fibrosus, pressing against nerve roots.
Osteophytes: Bone spurs from osteoarthritis can protrude into the spinal canal or foramina, compressing nerve roots.
Spondylolisthesis: One vertebra slipping over another can narrow the space through which the nerve root exits, causing compression.
Spinal Stenosis: Narrowing of the spinal canal or neural foramina can compress nerve roots; this is often due to a combination of disc degeneration, thickening of ligaments, and bone spur growth.
Diagnosis and Imaging:
MRI: Provides detailed images of soft tissues and bones, ideal for identifying disc herniations, ligament thickening, and osteophytes.
CT Scan: Useful for visualizing bone details and diagnosing osteophytes and spondylolisthesis.
X-rays: Can show alignment, vertebral slippage, and osteophytes but less detailed for soft tissue structures.
Understanding these anatomical details helps in diagnosing the specific levels of nerve root compression and planning appropriate treatment strategies, including physical therapy, medications, or potentially surgical interventions.
Joint structure of C spine
Cervical spine radiculopathy is more related to disc prolapse or bony disease?
Bony disease.
- Uncovertebral or facet joint arthritis.
Radicular radiation related to cervical radiculopathy may occur in what fraction of patients with cervical radiculopathy?
2/3
Other than pain, cervical radiculopathy commonly presents with what sign?
Depressed biceps and triceps reflexes.
What is the commonest cervical radiculopathy?
C7 radiculopathy (60%)
- The nerve root above the C7 vertebrae
Radiation is to the back of the forearm and into the middle fingers.
Depressed triceps reflex and muscle weakness.
What is the second commonest cervical radiculopathy?
C6 radiculopathy (20%)
Radiation to the superior lateral forearm and into the thumb and index fingers.
Weakness in the flexor carpi ulnaris (wrist flexion) but often uncertain.
Depressed biceps reflex.
Needs to be distinguished from CTS (carpal tunnel syndrome)
What is the more common cause of lumbar radiculopathy?
Disc herniation or spondylosis?
Disc herniation is far more common.
Very benign prognosis with 90% better within 3 months
What is the commonest lumbar radiculopathy?
It is the L5 radiculopathy.
This will usually present with paresthesia down the outer aspect of the leg and into the top of the foot.
Mild to moderate (but often symptomatic) weakness of dorsiflexion.
No reflex change
Need to differentiate it from a common peroneal nerve lesion.
- Can present with back pain, sensory change, and inversion as weak as eversion.
A patient with S1 radiculopathy would experience what symptoms?
Sensory changes running down the back of the leg and along the outside of the foot.
Weakness is rarely reported but commonly present. Unable to stand on tip toes on the affected foot.
Ankle jerk reflex suppressed
What levels are the ankle, patella, biceps, and triceps reflexes?
Disease of the atlanto-occipital joint can be associated with rheumatoid arthritis. This may lead to subluxation of C1 on C2 leading to what?
Paresthesia over the ear. Followed by medullary compression.
Is MRI or CT better for lumbar spine / C-spine
CT - Lumbar
MRI - C-spine
What are the three commonest focal mononeuropathies?
Carpal tunnel syndrome
Radial nerve palsy (saturday night palsy)
Common peroneal nerve palsy
How is carpal tunnel syndrome usually described?
Carpal tunnel syndrome (CTS) is commonly described as a condition that causes pain, numbness, and tingling in the hand and arm. The syndrome occurs when one of the major nerves to the hand—the median nerve—is compressed or squeezed as it travels through the wrist. Here’s a detailed breakdown of how carpal tunnel syndrome is typically described:
Anatomy Involved
Median Nerve: The primary nerve affected in CTS. This nerve provides sensation to the thumb, index, middle, and part of the ring fingers. It also controls some of the muscles at the base of the thumb.
Carpal Tunnel: A narrow passageway located on the palm side of the wrist, which houses the median nerve and tendons. It is bounded by bones and ligaments.
Symptoms
Numbness, Tingling, and Pain: Usually in the thumb, index, middle, and ring fingers. The sensation can be similar to the feeling of “pins and needles.”
Shock-like Sensations: These can radiate to the fingers.
Weakness: Patients may experience weakness in the hand and drop objects due to a lack of thumb muscle control.
Symptom Progression: Often symptoms start gradually and can be intermittent. As the condition worsens, symptoms may become constant and more severe.
Motor - weakness of abductor pollicus brevis, wasting, sparing of median long flexors.
Pathophysiology
Median Nerve Compression: The compression of the median nerve within the carpal tunnel is typically due to inflammation, swelling of the nerve itself, or increased pressure from surrounding tissues.
Risk Factors: Includes repetitive hand use, certain wrist positions, pregnancy, obesity, and conditions like diabetes, rheumatoid arthritis, and hypothyroidism.
Clinical Presentation
Nighttime Symptoms: Many patients report a worsening of symptoms during the night which may cause them to wake up.
Daytime Symptoms: Symptoms can be provoked or worsened by activities that involve prolonged wrist flexion or gripping.
Diagnosis
Clinical Examination: Includes Tinel’s sign (tapping over the median nerve at the wrist causes tingling in the fingers) and Phalen’s maneuver (holding the wrists in a flexed position leads to increased symptoms).
Electrophysiological Tests: Nerve conduction studies and electromyography can confirm median nerve compression and assess the severity.
Imaging: Ultrasound or MRI can be used to visualize the structure of the carpal tunnel and see any abnormalities.
Treatment
Conservative Management: Initial treatment often includes wrist splinting, especially at night, to alleviate symptoms by keeping the wrist in a neutral position. Nonsteroidal anti-inflammatory drugs (NSAIDs) may be used to reduce pain and inflammation.
Activity Modification: Changing patterns of hand use or ergonomic corrections can help alleviate symptoms.
Corticosteroid Injections: Can provide temporary relief by reducing inflammation and swelling within the carpal tunnel.
Surgery: Carpal tunnel release surgery is considered when conservative treatments fail. It involves cutting the ligament that forms the roof of the tunnel to relieve the pressure on the median nerve.
Carpal tunnel syndrome is a frequently encountered neuropathy, and its diagnosis is primarily clinical. Appropriate intervention can typically alleviate symptoms and prevent permanent nerve damage.
How is radial nerve palsy usually described?
Radial nerve palsy, often referred to as “Saturday night palsy,” is typically described as a neurological condition affecting the radial nerve, which impairs the affected individual’s ability to extend the wrist and fingers. This condition can arise from various causes, including compression, trauma, or injury to the radial nerve. Here’s a detailed breakdown of how radial nerve palsy is generally characterized:
Anatomy of the Radial Nerve
Path: The radial nerve is a major peripheral nerve of the arm that originates from the brachial plexus. It travels down the arm and supplies the muscles on the back of the arm and forearm, which are primarily responsible for extending the wrist and fingers.
Innervation: It provides motor innervation to the triceps brachii muscle of the upper arm, and to the extensor muscles of the forearm, which facilitate wrist and finger extension. It also provides sensory innervation to parts of the forearm and hand.
Symptoms of Radial Nerve Palsy
Motor Deficits:
Wrist Drop: The most characteristic symptom, where the patient is unable to extend the wrist at the joint, causing the wrist to hang limply.
Difficulty in Extending Fingers: Patients may not be able to straighten the fingers at the metacarpophalangeal joints.
Weakness in Arm: Difficulty in extending the elbow due to weakness in the triceps muscle, although this is less common.
Sensory Loss:
Numbness or Altered Sensation: This can occur on the back of the hand and on the outer surface of the forearm. Can also occur in the snuff box.
Patients often cant spread fingers as the ulnar intrinsic’s don’t work.
Causes
Compression: Prolonged pressure on the nerve, which can occur during sleep (hence “Saturday night palsy”), from wearing a tight cast, or from crutches. Often associated with sedated patients (alcohol, opiates)
Trauma: Fractures of the humerus bone or other injuries can directly damage the radial nerve.
Iatrogenic: Surgical procedures involving the arm may inadvertently affect the radial nerve.
Diagnosis
Clinical Examination: Physical examination revealing wrist drop and difficulty in finger extension are key indicators.
Nerve Conduction Studies and Electromyography (EMG): These tests help to confirm the diagnosis by assessing the electrical activity of muscles and the integrity of nerves.
Imaging: X-rays or MRI may be used to identify associated conditions such as fractures or to assess for other potential causes of nerve compression.
Treatment
Conservative Management:
Splinting: To support the wrist in an extended position, preventing further muscle shortening and joint stiffness.
Physical Therapy: To maintain muscle strength and joint range of motion.
Medication: Pain management with nonsteroidal anti-inflammatory drugs (NSAIDs) if required.
Surgical Intervention: In cases where nerve compression is due to mechanical causes (like tumors or fibrous bands) or trauma, surgical decompression or repair may be necessary.
Prognosis
The prognosis for radial nerve palsy depends on the underlying cause. If the nerve has been compressed without any anatomical disruption, recovery can be excellent with appropriate management. However, more severe injuries, such as those involving nerve transection or significant trauma, may require longer recovery times and potentially result in more permanent deficits.
Radial nerve palsy is generally well-managed with a combination of supportive care, physical therapy, and surgical intervention when necessary. Early diagnosis and treatment are crucial to maximize recovery and improve functional outcomes.
How is common peroneal nerve palsy usually described?
Common peroneal nerve palsy, also known as fibular nerve palsy, is a condition characterized by impairment of the peroneal nerve, which affects the ability to lift the foot at the ankle joint. This condition typically results in what is known as foot drop, where the foot drags during walking, and a characteristic high-stepping gait is adopted to compensate for the inability to lift the foot. Below is a detailed description of common peroneal nerve palsy:
Anatomy of the Common Peroneal Nerve
Path: The common peroneal nerve, a branch of the sciatic nerve, wraps from the back of the thigh around the head of the fibula near the knee. It then divides into superficial and deep branches.
Innervation:
The deep peroneal nerve innervates the anterior muscles of the lower leg, which are primarily responsible for dorsiflexion of the foot and toes (lifting the foot upward).
The superficial peroneal nerve innervates the lateral leg muscles that evert the foot (turning the sole of the foot outward).
Symptoms of Common Peroneal Nerve Palsy
Affects all the extensor compartment muscles of the leg. Look for weakness of the tibialis anterior (everts foot) and posterior (helps invert foot).
Motor Deficits:
Foot Drop: Most notably, the affected individual cannot dorsiflex the foot, causing the foot to drop and drag along the ground when walking.
Toe Drop: Difficulty in lifting the toes.
Gait Alteration: Development of a high-stepping gait to prevent the toes from catching on the ground.
Sensory Loss:
Numbness or altered sensation along the anterolateral aspect of the lower leg and the dorsum of the foot.
Causes
Compression: The nerve’s superficial location near the fibular head makes it susceptible to compression by external forces. Prolonged crossing of the legs, plaster casts, and tight boots are common culprits.
Trauma: Fractures, dislocations, or direct blows to the knee can damage the nerve.
Surgical Procedures: Procedures around the knee may inadvertently affect the peroneal nerve.
Systemic Conditions: Conditions like diabetes mellitus can predispose individuals to nerve compressions due to a general susceptibility to peripheral neuropathies.
Diagnosis
Clinical Examination: Observation of gait, assessment of muscle strength in foot and toe dorsiflexion, and testing for sensory deficits.
Nerve Conduction Studies and Electromyography (EMG): To evaluate the electrical activity of muscles and the integrity of the nerve along its course.
Imaging: MRI or ultrasound may be used to identify the site of nerve compression or to visualize any structural anomalies causing nerve damage.
Treatment
Conservative Management:
Physical Therapy: To strengthen the muscles and maintain range of motion.
Orthotic Devices: Ankle-foot orthoses (AFO) may be used to support the foot in a normal position, aiding in walking and preventing injuries.
Medication: Anti-inflammatory drugs for pain and inflammation.
Surgical Intervention: If the palsy is due to compression by a cyst or other growths, surgical decompression or removal might be necessary. Surgery may also be considered in chronic or severe cases where no improvement is seen with conservative measures.
Prognosis
Recovery from common peroneal nerve palsy depends on the severity of the nerve damage and the underlying cause. Mild cases, especially those caused by reversible compression, often recover fully with appropriate treatment. Severe injuries involving nerve transection or significant trauma may have a poorer prognosis and might not recover completely.
Common peroneal nerve palsy is a relatively common neurologic condition that can significantly impact mobility and quality of life. Timely and appropriate management is crucial to improving outcomes and helping patients regain functional use of their foot and ankle.
What are common causes of provoked seizures?
Alcohol and BDZ withdrawal.
Medications
Metabolic
The seizure must occur within the first week of insult (usually first few days).
Acute symptomatic seizures are caused by?
They are early seizures associated with acute CNS insult, stroke, meningitis, head trauma.
What is the difference between generalised seizures and partial (focal) seizures?
Seizures are broadly categorized based on how and where abnormal brain activity begins and whether awareness is affected during the event. The two main categories are generalized seizures and partial (or focal) seizures, each with distinct characteristics:
Generalized Seizures:
Generalized seizures affect both hemispheres (sides) of the brain simultaneously and are characterized by widespread electrical discharges that involve the entire brain.
This category includes several different types of seizures:
1) Tonic-Clonic Seizures (formerly known as grand mal seizures): These are the most recognized type, characterized by an initial muscle stiffening (tonic phase) followed by rhythmic jerking movements (clonic phase).
2) Absence Seizures (formerly known as petit mal seizures): These are typically brief and may involve subtle body movements such as eyelid fluttering. The person usually stares blankly and does not respond to the environment during the seizure.
3) Myoclonic Seizures: These involve sudden, brief jerks or twitches of muscles or muscle groups.
4) Atonic Seizures (also known as drop attacks): During these seizures, there is a sudden loss of muscle tone leading to collapse or falling down.
5) Tonic Seizures: These involve a sudden stiffness of muscles, particularly those in the back, arms, and legs.
6) Clonic Seizures: These are characterized by rhythmic, jerking muscle contractions, usually affecting the neck, face, and arms.
People experiencing generalized seizures often lose consciousness or have changes in their level of awareness during the seizure.
Partial (Focal) Seizures
Partial seizures, now more commonly referred to as focal seizures, originate in a specific part of the brain and are categorized based on the level of awareness they affect:
1) Focal Aware Seizures (formerly known as simple partial seizures): During these seizures, the individual remains conscious and aware. Symptoms can include involuntary jerking of a body part, changes in emotions, sensations, and feelings, or sensory distortions such as tingling, dizziness, and seeing flashing lights.
2) Focal Impaired Awareness Seizures (formerly known as complex partial seizures): These seizures involve a change or loss of consciousness or awareness. Individuals may appear dazed and confused; they may not be able to respond to questions or directions. Actions during the seizure may seem purposeful but are unconscious, such as fumbling with clothes or smacking lips.
3) Focal to Bilateral Tonic-Clonic Seizures: These start in one part of the brain as a focal seizure but then spread to both sides of the brain, becoming a generalized tonic-clonic seizure. This progression involves the initial symptoms of a focal seizure followed by the general symptoms of a tonic-clonic seizure.
Summary of Differences
Origin of Seizure Activity:
Generalized Seizures: Begin and involve both sides of the brain simultaneously.
Partial (Focal) Seizures: Start in one specific area of the brain.
Consciousness:
Generalized Seizures: Typically involve loss of consciousness.
Partial Seizures: May or may not involve impairment of consciousness, depending on the type.
Symptoms:
Generalized Seizures: Often involve full-body spasms, stiffening, or jerks.
Partial Seizures: Symptoms are generally related to the brain area where the seizure begins and can be isolated to specific body parts or experiences.
Understanding the type of seizure an individual experiences is crucial for effective treatment and management, including the choice of medication, lifestyle adjustments, and, in some cases, surgical options to control seizures.
What anti epileptic drugs are best for focal seizures?
What ones for generalised absence seizures? What ones offer broad cover of focal and general?
Focal seizures, think carbamazepine, phenytoin.
Generalised absence - think ethosuximide and acetozolamide
For broad cover of focal and generalised seizures things like valproate, lamotrigine, and topiramate are good.
What is Kernig’s sign?
Pain when flexing the hip and extending the knee.
It is used to assess for possible meningism.
Note in meningism the brain itself is not involved, so their should be no seizures, or disturbance to consciousness. (Except in late stages due to CSF obstruction or parenchymal invasion).
What is the definitive treatment for Neisseria meningitidis and for Streptococcus pneumonia induced meningitis?
N. m = penicillin
S. p = Pencillin, Ceftriaxone, vancomycin
