EDNA
Peripheral Neuropathy due to axonal loss is characterized by which of the following?
A. Slow conduction velocity and low amplitude
B. Prolonged distal latencies
C. Absence of muscle fiber activity
D. Low amplitude and preserved conduction velocity
E. Dispersion of evoked compound action potentials
D
Axonal loss peripheral neuropathy can result from toxic, metabolic, autoimmune, or inflammatory disorders. Axonal loss results in low amplitudes with preserved nerve conduction velocity. Demyelinatinon results in slow conduction velocity and prolonged latency, dispersion of evoked compound action potentials, and conduction block. On EMG, axonal loss is characterized by the presence of spontaneous muscle fiber activity are test, which is caused by lack of neuro-regulation.
A. Demyelinating disorders
B. Marked prolongation of distal latencies is associated with demyelinating disorders
C. Axonal loss is characterized by spontaneous muscle fiber activity at rest sa a result of a loss of neural regulation in denervated areas
E. Demyelinating disorders are characterized by a dispersion of evoked compound action potentials
What is the most likely dx of a 4.5 yo with severe peripheral motor and sensory neuropathy in a child that has tightly curled hair (unlike either parent) and cognitive impairment and a sural nerve biopsy remarkable for enlarged axons filled with disrupted neurofilaments
A. Infantile neuroaxonal dystrophy
B. Late infantile neuronal ceroid lipofuscinosis
C. Giant axonal neuropathy
D. Subacute necrotizing encephalomyelopathy
C. Giant anxonal neuropathy
The underlying pathology in giant cell neuropathy is disruption of intermediate filament organization that predominantly affects the neurofilaments. the age of first symptoms is before 5 yo. both central and peripheral axons are disrupted and manifest impaired function. Boys and girls are equally affected. symmetrical distal atrophy is universal with impairment of vibratory sensation and proprioception with diminished tendon reflexes
A. characterized by large axonal eosinophilic spheroids forming as a result of axonal swelling in teh cerebral and anterior horn cell grey matter
B. symptoms begin between 2-4 yo, progressive cognitive impairment, abnormal movements. visual impairment begins by age 4yo and progress to blindness
D. Leigh disease, presents between 3 - 12 mo with neuro decompensation associated with lactic acidosis
Which of the following is not characteristic of congenital muscular dystrophies?
a. Decreased movements in utero
b. Hypotonia and weakness at birth
c. Autosomal dominant inheritance
d. Dystrophic changes on muscle biopsy
e. Frequent involvement of the brain
C. AD inheritance
The congenital muscular dystrophies are a group of disorders mostly inherited in an autosomal recessive fashion. In utero, there may be decreased movements. At birth, these children are hypotonic and weak, presenting with arthrogryposis, and may develop respiratory insufficiency and bulbar dysfunction. With time they may develop contractures and scoliosis. These patients also have developmental delay and developmental anomalies of the cerebral cortex. Because of cortical involvement, seizures occur in some subtypes of these disorders. Creatine kinase is markedly elevated. EMG shows myopathic changes
A 32-year-old woman presents for a blood draw as part of a preemployment health evaluation. After the blood draw, she starts to feel lightheaded, begins sweating profusely, and she loses consciousness and lies listless on the floor. There is no convulsive activity or loss of bowel or bladder control. Approximately 15 seconds later, she regains consciousness. She feels slightly lightheaded but is not confused and is able to recall all the events preceding her loss of consciousness. A few minutes later she is feeling fine. What is the most likely diagnosis in this patient?
A. Vasovagal syncope
B. Glossopharyngeal neuralgia
C. Seizure
D. Carotid sinus hypersensitivity
E. Third ventricular mass
A. vasovagal syncope
The other options are all potential causes of syncope. Glossopharyngeal neuralgia is characterized by severe pain in the hypopharynx and pharynx, tongue, and ear, with hypotension and bradycardia that when severe may be associated with syncope. It is often posttraumatic but can occur with neck tumors as well. There are no features in the case to suggest glossopharyngeal neuralgia. A lack of postictal confusion and absence of convulsions help distinguish syncope from seizures in this case. However, tonic stiffening and a few myoclonic jerks are not uncommon in syncope. Carotid sinus hypersensitivity is a syncope triggered by maneuvers that increase pressure on the carotid sinus, such as a tight collar. A third ventricular tumor, such as a colloid cyst, can lead to syncope with postural changes if the change in posture leads to obstruction of the third ventricle, leading to increased intracranial pressure (ICP).
Spinal muscular atrophy (SMA) is a hereditary disease affecting the lower motor neurons. What is true about SMA?
A. It is an autosomal dominant disorder.
B. SMA is classified into five types, based on ages of onset, severity, and progression of symptoms. Approximately 95% of all five types are caused by defects in the SMN-1 gene.
C. SMA type I, also called Werdnig-Hoffmann disease, is evident by the time a child is 6 months old.
D. B and C
E. None of the above.
SMA is an autosomal recessive disorder and is one of the more common childhood inherited lethal diseases. The symptoms are aligned according to a spectrum and may vary from neonatal death to progressive symmetrical muscle weakness first appearing in adulthood.
Incorrect Answers:
A. SMA is an autosomal recessive disorder.
A 27-year-old man is involved in a motor vehicle accident and is ejected from the car. He suffers acute spinal cord injury with cord transection at the level of C5-C6. The following findings would be present during the first week of injury except:
A. Flaccid weakness of his lower extremities
B. Atonic bladder with overflow incontinence
C. Decreased rectal tone
D. Patellar and ankle areflexia
E. Upgoing plantar reflexes
E. Upgoing plantar reflexes
After spinal cord injury there are two phases: an initial phase of spinal shock (1-6 weeks) followed by a second phase of increased reflex activity with spasticity.
Initially, with complete spinal cord injury, the patient will have a flaccid weakness with areflexia below the lesion, atonic bladder with overflow incontinence, distention of the bowel with absence of peristalsis, constipation, depressed rectal tone, and abolished genital reflexes
A few weeks after the spinal cord injury, the patient will start presenting features of increased reflexic activity below the lesion and upper motor neuron signs.
A 6-year-old boy is brought for evaluation of stiffness. His legs are stiff, and he has difficulty relaxing muscles after contracting them. He cannot release objects easily once grasped with his hands, and when he closes his eyes, it takes a few seconds before he is able to open them completely. If he performs the same motor task multiple times, then it becomes easier. When his thenar eminence is percussed, there is prolonged contraction and delayed relaxation. His father and grandfather have similar clinical features that started around the same age. Which of the following is the most likely diagnosis?
A. Paramyotonia congenita
B. Myotonia congenita, Becker’s disease
C. Myotonia congenita, Thomsen’s disease
D. Hyperkalemic periodic paralysis
E. Hypokalemic periodic paralysis
C. This patient has myotonia congenita, and more specifically, Thomsen’s disease.
There are two types of myotonia congenita: Thomsen’s disease, which is autosomal dominant, and Becker’s disease, which is autosomal recessive. This group of disorders is caused by a channelopathy secondary to pathogenic variants in the voltage-dependent chloride-channel gene CLCN1 on chromosome 7q. The main manifestation is myotonia, which is an impaired muscle relaxation as seen when the patients cannot relax their handgrip after grasping an object, and also manifested on percussion (percussion myotonia), leading to contraction and delayed relaxation. Myotonic potentials can be detected on EMG.
In myotonia congenita, as opposed to paramyotonia, there is a “warm-up” phenomenon, in which the myotonia improves after repetitive muscle activation.
Becker’s disease is the recessive form that presents later, usually in the second decade of life, is more severe than the dominant form, and may manifest with weakness after severe episodes of myotonia.
6 yo boy presents for a well child visit. his parents report difficulty climbing and frequent falls. A physical exam is remarkable for calf pseudohypertrophy and difficulty standing when seated on the floor. Eval is most likely to show which of the following?
A. Absence of dystrophin staining in muscle biopsy
B. Distal muscles affected more than proximal
C. Normal CK levels
D. EKG with bradycardia
A. Absence of dystrophin staining in muscle biopsy - DMD is from a mutation leading to an absence of dystrophin
DMD - Gower sign present on exam.
B. Proximal > Distal weakness
C. Elevated Ck
D. Abnormal ECG --> Tachycardia
Also often associated with intellectual disability
A 40-year-old man presents with pain in the right lower extremity radiating from the buttock down to his foot. He has pain and sensory deficits along the posterior thigh, leg, and lateral aspect of the foot. There is weakness on plantarflexion. Patellar reflex is normal, but the ankle reflex is depressed on the right side. Which of the following is the most likely diagnosis?
A. L2 and L3 radiculopathy
B. L4 radiculopathy
C. L5 radiculopathy
D. S1 radiculopathy
E. Peroneal neuropathy
D. S1 radiculopathy
Lumbosacral radiculopathy is commonly caused by disk herniation or degenerative spine changes. S1 radiculopathy commonly manifests as pain radiating from the buttock down the posterior thigh, posterior leg, and lateral foot, with sensory impairment in this dermatomal region, especially the lateral foot and fifth toe. The most prominent weakness is plantarflexion and toe flexion, and the ankle deep tendon reflex will be reduced or absent. Muscles involved in S1 radiculopathies include the abductor hallucis, abductor digiti quinti pedis, soleus, medial and lateral gastrocnemius, extensor digitorum brevis, biceps femoris (long and short head), and gluteus maximus. Muscles partially innervated by S1 that may also be affected are the tibialis posterior, flexor digitorum brevis, gluteus medius, and tensor fasciae latae. Although the SNAPs should be normal in S1 radiculopathies, the H-reflex is commonly reduced or absent
A 39-year-old woman with type 1 diabetes mellitus presents for evaluation. She has numbness in a glove and stocking distribution affecting hands and feet. She has no pain. There is loss of sensation to vibration and proprioception, and she is hyporeflexic distally. Which of the following most likely explains her symptoms?
a. Small-fiber diabetic neuropathy
b. Large-fiber diabetic neuropathy
c. Diabetic polyradiculoneuropathy
d. Diabetic mononeuropathy
e. Diabetic amyotrophy
B. Large fiber diabetic neuropathy
This patient has a large-fiber diabetic neuropathy. This is usually a length-dependent neuropathy, in which the patient has numbness and paresthesias that are painless. The distribution is symmetric, affecting hands and feet in a glove and stocking distribution. On examination, there is loss of vibratory sense and proprioception, as well as loss of deep tendon reflexes. Sensory ataxia may occur later in the course of the disease. Weakness may occur but is not a prominent feature.
Diabetic mononeuropathy can affect either the peripheral or cranial nerves and usually involves one nerve. If several nerves are involved, the presentation is usually asymmetric, unlike in this case. Small-fiber diabetic neuropathy is discussed in question 49. Diabetic polyradiculoneuropathy and diabetic amyotrophy are discussed in question 42.
An 8-year-old boy presents for evaluation of episodes of stiffness and difficulty relaxing his muscles. He has difficulty opening his eyes after closure and difficulty releasing after grasping with his hands. These symptoms are worse after exercising and performing the same task multiple times and also worsen with exposure to cold. His father also has similar symptoms. Which of the following is the most likely diagnosis?
a. Paramyotonia congenita
b. Becker’s disease
c. Thomsen’s disease
d. Hyperkalemic periodic paralysis
e. Hypokalemic periodic paralysis
A. paramyotonia congenita
AD sodium channelopathy caused by a pathogenic variant in the sodium-channel gene SCN4A. The manifestations are similar to those of myotonia congenita; however, unlike in myotonia congenita, in paramyotonia congenita, there is no “warm-up” phenomenon. Rather, repeated exercise accentuates myotonia, which is most clearly appreciated in the eyelids. Hence, the name is derived from “para”-doxical reaction to exercise. Exposure to cold worsens the myotonia and may precipitate weakness, also in contrast to myotonia congenita. Percussion myotonia is rare but can be seen after exposure to cold. EMG after cold exposure can also demonstrate fibrillation potentials followed by electrical inexcitability.
Symptoms of DMD include:
A. Awkward manner of walking, stepping, or running
B. increased lumbar lordosis
C. higher risk of neurobehavioral disorders
D. skeletal deformities
E. All of the above
E. All of the above
Pts tend to walk on their forefeet because of increased calf tone as well as toe walking because of knee extensor weakness
An infant is diagnosed with a congenital muscular dystrophy. Clinically, he is weak and has multiple contractures with distal hyperlaxity. Examination of his feet shows protrusions of the calcanei. Which is the most likely diagnosis?
A. Fukuyama-type congenital muscular dystrophy
B. Laminin-α-2 deficiency
C. Walker-Warburg syndrome
D. Muscle-eye-brain disease
E. Collagen VI–related muscular dystrophy (Ullrich’s congenital muscular dystrophy)
E. Collagen VI–related muscular dystrophy (Ullrich’s congenital muscular dystrophy)
This patient likely has a severe form of collagen VI–related muscular dystrophy or Ullrich’s congenital muscular dystrophy. This presents with neonatal weakness, contractures and distal hyperlaxity, as well as protrusion of the calcanei. It is related to Bethlem myopathy—a milder form of collagen VI–related dystrophy.
Walker-Warburg syndrome is a severe autosomal recessive disorder of glycosylation of α-dystroglycan characterized by muscular dystrophy and brain and ocular abnormalities. Patients are hypotonic at birth with elevated creatine kinase levels. The ocular malformations include microphthalmia, colobomas, cataracts, glaucoma, corneal opacity, retinal dysplasia, and optic atrophy. There are multiple brain malformations reported in this syndrome, including hydrocephalus, aqueductal stenosis, cerebellar hypoplasia, and cortical abnormalities.
Muscle-eye-brain disease is another autosomal recessive disorder of glycosylation of α-dystroglycan, in which there is also muscular dystrophy and brain and ocular abnormalities; however, the cortical changes are milder, and the white matter changes are more focal. The eyes are also affected to a lesser degree than Walker-Warburg syndrome.
A patient presents with a several-month history of gradually progressive sensory loss to pain and temperature over his shoulders and both arms bilaterally, with preserved sensation to tactile touch, vibration, and proprioception. On examination, he has findings suggestive of multiple old injuries in both upper limbs. He also has weakness and atrophy in both upper extremities, with minimal findings in the lower extremities. Which of the following is correct regarding this condition?
A. Syringomyelia can cause this syndrome
B. The MRI of his spine may show an infarct in the anterior spinal artery territory
C. The syndrome is consistent with Brown-Séquard
D. The findings suggest subacute combined degeneration of the spinal cord
E. This patient has a watershed infarct of the spinal cord
A. Syringomyelia can cause this syndrome
This patient has a dissociated sensory loss with loss of sensation to pain and temperature and preserved sensation to tactile touch, vibration, and proprioception in his upper extremities. This clinical syndrome is seen with central spinal cord lesions in which there is compromise of the crossing fibers in the midline anterior to the central canal, which carry the sensory input related to pain and temperature (spinothalamic tract). Usually, the distribution of this sensory loss is described as a “cape-like” or “shawl-like” distribution. Since it does not affect the posterior columns, the sensory modalities carried by this pathway including vibration and proprioception are not affected. This dissociated sensory loss is seen in syringomyelia, in which there is a cavitation in the central part of the spinal cord, usually in the cervical region, sometimes extending upward to the brainstem or downward to the thoracic region. Patients with syringomyelia, given their lack of sensory input in their upper extremities, may experience repeated trauma and recurrent injuries such as burns to the fingers while cooking. Syringomyelia may be associated with other developmental anomalies of the vertebral column or skull, as well as with Chiari malformations.
This patient does not have a spinal cord infarct, since the history is not that of a sudden/acute onset but rather that of a gradually progressive illness. There is also no significant motor disturbance, such as that seen from infarcts in the anterior spinal artery territory affecting the anterior horns and corticospinal tracts.
Brown-Séquard syndrome, or hemisection of the spinal cord, is a characteristic syndrome resulting in crossed sensory loss. There is loss of pain and temperature sensation contralateral to the side of the lesion due to interruption of the crossed spinothalamic tract. There is simultaneous ipsilateral loss of proprioception and vibration sensation below the level of the lesion from interruption of the ipsilateral posterior columns, as well as ipsilateral weakness below the lesion from corticospinal tract involvement.
The presentation is not consistent with subacute combined degeneration of the spinal cord. This would affect posterior columns and subsequently anterolateral columns and is characterized by dysesthesias, alteration in proprioception and vibration, and spastic paraparesis.
a 22 wk old girl presents with sudden onset of diffuse hypotonia, ptosis, dysphagia, weak cry, and dilated, sluggish pupils. Her mother reports she has been constipated and has a poor suck when feeding. EMG shows a reversal of the presynaptic block after 20-50 Hz stimulation, then a gradual increase in the size of hte motor unit potentials. What is the dz?
A. Infantile myasthenia
B. Infantile botulism
C. Infantile spinal muscular atrophy
D. Infantile myotubular myopathy
B. Infantile botulism
Botulism toxin causes cholinergic blockade. EMG shows a presynaptic transmission defect, where repetitive nerve stimulation show an incremental response due to the faciliation of acetylcholine release
A. infantile myasthenic syndromes dont present with dilated pupils, absent reflexes, constipation
B. Infantile SMA does not have ptosis, dilated pupils
D. Infantile myotubular myopathy presents as low tone from birth and subsequent motor delay
On examination the patient has weakness in the shoulder muscles, with partial wekaness in the biceps. He has good strength in wrist flexion.
Which of the following is the most likely condition and where is the lesion?
A. Upper brachial plexus: acute brachial plexus syndrome
B. Upper and lower brachial plexus: brachial plexitis
C. Spinal cord compression: C4-C6
D. Spinal cord compression: C8-T1
Acute brachial plexus neuritis is disorder characterized by severe shoulder and upper arm pain followed by marked upper arm weakness in the absence of trauma. Even though the boy plays football, there was no impact near the time of the pain onset. This distinct disorder typically involves the upper plexus, which supplies the shoulder and upper arm muscles. Weakness is frequently found in the rhomboideus major and minor muscles (dorsal scapular nerve), supraspinatus and infraspinatus muscles (suprascapular nerve), deltoid muscle (axillary nerve) and biceps muscle (musculocutaneous nerve).
B. Lower brachial plexus roots contribute to the median and ulnar nerves that innervate the wrist flexors. The lower plexus is not typically involved in this syndrome.
C. The clinical course of spinal cord compression in most cases would be more gradual.
D. Acute brachial plexus syndrome typically involves the upper plexus.
A 58-year-old female patient presents with proximal muscle weakness, hyporeflexia, and dry mouth. You suspect Lambert-Eaton myasthenic syndrome. Which finding do you expect when confirming the diagnosis with electrodiagnostic studies?
A. Increased CMAP amplitude at baseline
B. Decreased CMAP amplitude after exercise
C. Incremental increase in CMAP amplitude after repetitive nerve stimulation at high frequency
D. Single-fiber electromyography shows increased jitter and transmission blocking that improve at lower firing rates
E. Prolonged distal latencies on NCS
C. Incremental increase in CMAP amplitude after repetitive nerve stimulation at high frequency
Lambert-Eaton myasthenic syndrome is strongly associated with small cell lung cancer. The typical characteristics include progressive proximal muscle weakness, hyporeflexia, and dry mouth due to autonomic dysfunction. In atypical cases, isolated muscle weakness may occur. It is caused by a reduction of acetylcholine release from presynaptic neurons due to autoimmunity against voltage-gated calcium channels. Non-neoplastic disease is associated with other disorders with an immune-mediated mechanism. Muscle strength improves, and deep tendon reflexes may be recovered after a period of brief muscle activation of 10-15 seconds. Anti-P/Q voltage-gated calcium channel antibody testing and electrodiagnostic studies are used to confirm the diagnosis. Motor and sensory nerve conduction studies show a reduced baseline CMAP amplitude with typically normal sensory amplitude, normal conduction velocity, and normal distal latency. Repetitive nerve stimulation testing at high frequencies (10-50 Hz) will result in increased CMAP amplitude of >100%, as will a 10-second period of maximum isometric muscle contraction. Single-fiber electromyography can be performed if the diagnosis is unclear after routine electrodiagnostic studies. It will show jitter and transmission blocking that improve at higher firing rates.
Incorrect Answers:
A. CMAP is decreased in amplitude at baseline.
B. CMAP amplitude increases after a brief period of maximum exercise.
D. Increased jitter and transmission blocking are improved at high transmission rates.
E. Distal latencies and conduction velocities are normal.
A 28-year-old woman with gestational diabetes gives birth to a 4500 g infant. Delivery is complicated, resolved using the McRoberts maneuver by the obstetrician. You are asked to evaluate the infant since he does not seem to be moving his right arm as much as his left arm. The right arm appears to be limp and internally rotated. You suspect a brachial plexus injury has occurred. Which of the following is correct regarding newborns with brachial plexus injury?
A. Brachial plexus injury during delivery invariably results from poor obstetrical technique.
B. Klumpke palsy is associated with a good prognosis.
C. Erb-Duchenne palsy is associated with a poor prognosis.
D. Risk factors include fetal macrosomia and breech presentation.
E. Early surgical intervention with nerve grafting is recommended.
D. Risk factors include fetal macrosomia and breech presentation.
The brachial plexus, which consists of C5-T1 nerve roots, can be injured during delivery. Erb-Duchenne palsy, also known as Erb’s palsy, refers to injury to the upper trunk of the brachial plexus, which consists of C5 and C6 nerve roots. Classically, upper trunk injury presents with the “waiter’s tip” hand, where the arm and forearm are internally rotated and the fingers are flexed. Klumpke palsy refers to injury to the lower trunk, which is made up of C8 and T1 nerve roots. Risk factors for brachial plexus injury include fetal macrosomia, shoulder dystocia, and breech presentation. Gestational diabetes is a risk factor for fetal macrosomia, which refers to increased neonatal weight. Shoulder dystocia refers an infant’s shoulder becoming lodged within the pelvis, which is typically corrected by special maneuvers performed by the obstetrician such as the McRoberts maneuver. In general, upper trunk injury or Erb’s palsy has a good prognosis with complete resolution in up to 90% of cases within 1 year. Lower trunk injury or Klumpke’s palsy has a poorer prognosis, with an estimated 40% of cases resolving within 1 year. Treatment of neonatal brachial plexus injury focuses on prevention of contractures using splints as well as passive and active range of motion. Surgery is reserved for cases where there is no early improvement.
Incorrect Answers:
A. There are multiple risk factors associated with neonatal brachial plexus injury, including fetal macrosomia, shoulder dystocia, and breech presentation. Obstetrician experience is not necessarily associated with brachial plexus injury.
B. Klumpke's palsy, which is a lower trunk injury, is associated with a poorer prognosis compared to Erb’s palsy.
C. Erb’s palsy is associated with a good prognosis, with most affected individuals completely recovering within 1 year.
E. Surgical intervention is reserved for cases where there is no early improvement.
Most cases of spinal epidural abscess are caused by which pathogen?
A. anaerobes
B. staph aureus
c. streptococci
d. gram negative bacilli
B. Staph aureus
up to 63% of spinal epidural abscesses are caused by staph aureus, followed by gram neg bacilli, then streptococci
A 50-year-old male has been practicing for a table tennis tournament for several months. He presents complaining of pain shooting up the thumb with tingling and numbness over the dorsal thumb and dorsolateral hand. Exam reveals decreased sensation to fine touch and pinprick over the dorsolateral aspect of the right hand with otherwise normal motor strength and normal sensation throughout. What is the most likely diagnosis?
A. Pronator teres syndrome
B. Carpal tunnel syndrome
C. Superficial sensory radial neuropathy
D. C7 radiculopathy
E. C8 radiculopathy
C. Superficial sensory radial neuropathy
This patient's history and examination are consistent with superficial sensory radial neuropathy. This type of neuropathy, also called Wartenberg's syndrome, can result from compression or irritation of this nerve and often occurs in patients who play sports that require repetitive pronation and supination. Compression may also occur as the nerve travels between the brachioradialis and extensor carpi radialis longus tendons. Symptoms include pain and paresthesia over the dorsolateral hand and the dorsal thumb. The superficial sensory radial nerve is a pure sensory nerve, so there is no associated weakness or atrophy. Treatment includes avoidance of activities that compress the nerve or reproduce the symptoms. Pharmacological treatment includes medications used for neuropathic pain (amitriptyline, pregabalin, or gabapentin).
Incorrect Answers:
A. Pronator teres syndrome, a median nerve syndrome, results in sensory loss over the lateral aspect of the palm.
B. Carpal tunnel syndrome is a median nerve syndrome that results in the median nerve territory with involvement of the first 3 digits and the radial half of the fourth digit.
D. C7 radiculopathy results in weakness in elbow extension and wrist flexion.
E. C8 radiculopathy results in weakness in thumb extension and ulnar deviation at the wrist.