Neuromuscular I Flashcards
1
Q
giant axonal neuropathy (GAN)
A
autosomal recessive disorder that manifests in early childhood. Predominantly axonal Sensorimotor neuropathy, corticospinal tract involvement with upper motor neuron signs, and optic atrophy leading to vision loss.
Neuropath large focal axonal swelling that contains tightly packed disorganized neurofilaments. GAN gene that encodes for gigaxonin
2
Q
Refsum’s disease (RD)
A
autosomal dominant peroxisomal disorder. Fatty acid metabolism, leading to accumulation of an intermediate in this pathway, phytanic acid. retinitis pigmentosa (with night blindness and visual field constriction), cardiomyopathy, and skin change. Large-fiber sensorimotor neuropathy, hearing loss, anosmia, ataxia, and cerebellar signs
Rx reduce dietary intake of phytanic acid
3
Q
F wave obtained by?
A
after supramaximal stimulation of a motor nerve.
4
Q
Significant axon loss lesions?
A
produce reductions in action potential amplitudes and tend to have preserved or mildly reduced conduction velocities
5
Q
NCS modalities?
A
sensory and motor conduction studies.
6
Q
Sensory NCS
A
stimulating a sensory nerve while recording the transmitted potential at a different site along the same nerve. Three main measures can be obtained: SNAP amplitude, sensory latency (onset and peak), and conduction velocity.
7
Q
SNAP
A
amplitude (in microvolts) represents a measure of the number of axons conducting between the stimulation site and the recording site.
8
Q
Sensory latency
A
(in milliseconds) is the time that it takes for the action potential to travel between the stimulation site and the recording site of the nerve.
9
Q
conduction velocity
A
is measured in meters per second and is obtained dividing the distance between stimulation site and the recording site by the latency: Conduction velocity = Distance/Latency.
10
Q
Motor NCS
A
are obtained by stimulating a motor nerve and recording at the belly of a muscle innervated by that nerve
11
Q
Motor CMAP
A
CMAP is the resulting response, and depends on the motor axons transmitting the action potential, status of the neuromuscular junction, and muscle fibers.
12
Q
CMAP/SNAP interpretation
A
prolonged latencies and slow conduction velocities correlate with demyelination, decrease in the amplitudes correlates with axon loss lesions.Low amplitudes can result from demyelinating conduction block when the nerve stimulation is proximal to the block.
13
Q
F-wave
A
F-wave is obtained after supramaximal stimulation of a motor nerve while recording from a muscle.travels antidromically (conduction along the axon opposite to the normal direction of impulses) along the motor axons toward the motor neuron, backfiring and then traveling orthodromically (conduction along the motor axon in the normal direction) down the nerve to be recorded at the muscle.
14
Q
H-wave
A
H-reflex is the electrophysiologic equivalent of the ankle reflex (S1 reflex arc) and is obtained by stimulating the tibial nerve at the popliteal fossa while recording at the soleus. The electrical impulse travels orthodromically through a sensory afferent, enters the spinal cord, and synapses with the anterior horn cell, traveling down the motor nerve to be recorded at the muscle.
15
Q
Large polyphasic motor unit potentials (MUPs)
A
seen in acute neuropathic lesions, but rather in chronic ones.
16
Q
Insertional activity
A
is recorded as the needle is inserted into a relaxed muscle. It is increased in denervated muscles and myotonic disorders, and is decreased when the muscle is replaced by fat or connective tissue and during episodes of periodic paralysis
17
Q
Spontaneous activity
A
is assessed with the muscle at rest, and examples include fibrillation potentials, fasciculation potentials, and myokymia and myotonic potentials. All spontaneous activity is abnormal.
18
Q
Voluntary contraction
A
MUPs are obtained while the needle is inserted into the muscle during voluntary contraction. Characteristics include recruitment pattern and MUP morphologic features, such as duration, amplitude, and configuration.
19
Q
Recruitment
A
is a measure of the number of MUPs firing during increased force of voluntary muscle contraction
20
Q
Axon loss lesions
A
reduced recruitment is characterized by a less-than-expected number of MUPs firing more rapidly than expected.
21
Q
Myopathic processes
A
Early or rapid recruitment occurs in myopathic processes with loss of muscle fibers, in which an excessive number of short-duration and small-amplitude MUPs fire during the muscle contraction.
22
Q
Poor voluntary effort or with CNS disorders
A
causing weakness, recruitment is reduced with normal MUPs firing at slow or moderate rates, sometimes in a variable fashion
23
Q
neuropathic disorders with denervation and reinnervation
A
MUPs disclose increased duration and amplitude, and may be polyphasic
24
Q
myopathic disorders
A
MUPs are of reduced duration and amplitude, and may also be polyphasic.
25
Radiculopathy NCS?
normal SNAPs despite sensory symptoms, because SNAPs are recorded distal to the lesion, in the postganglionic projections from the dorsal root ganglion. Thus radiculopathies are usually diagnosed with the needle EMG component rather than the NCS component of the electrodiagnostic study.
26
Radiculopathy path?
occurs from an intraspinal canal lesion resulting in damage of the preganglionic fibers. The cell body in the dorsal root ganglia and the postganglionic fibers remain unaffected, and therefore, even though sensory symptoms are prominent, the SNAPs are normal.
27
axon loss radiculopathy
injure motor fibers in the intraspinal canal region affecting the respective myotome. This leads to denervation, with fibrillation potentials seen 3 weeks after the onset of motor axon loss, decreased recruitment, and 3 to 6 months later, large and polyphasic motor unit potentials (MUPs). The presence of these large and polyphasic MUPs is dependent on reinnervation and collateral innervation, typically occurring in a proximal to distal fashion, with proximal muscles more successfully reinnervated as compared to distal muscles.
28
SFEMG
highly sensitive but not specific for MG, being frequently abnormal in other neuromuscular junction
29
Type 1 muscle fibers
also called slow-oxidative, have slow ATPase activity and large oxidative capacity, with large numbers of mitochondria. They are red in color and small in diameter.
30
Type IIa fibers
fast oxidative glycolytic fibers, and have fast ATPase activity, with high glycolytic capacity and moderate oxidative capacity. These fibers are fast and resistant to fatigue.
31
Type IIb fibers
fast-oxidative-glycolytic fibers, and have fast ATPase activity, with high glycolytic capacity but low oxidative capacity. These fibers are fast and fatigable. Their color is pale and diameter is large.
32
Demyelination cardinal features
conduction velocity is reduced (normal >50 m/s), peak latency is prolonged (normal is <4 ms) and CMAP amplitude dispersion
33
CIDP dx
CIDP is the diagnosis when symptoms progress or relapse beyond 8 weeks.
34
Peripheral nerve injury severity
can range from focal demyelination to axonal injury and finally nerve transection with discontinuity of the nerve. Electrophysiologic studies can help determine the degree of injury.
35
Focal nerve injury
segmental demyelination, which is characterized by the presence of slowing at a specific site, or the presence of a conduction block, which is a decrease in the CMAP amplitude with proximal stimulation as compared to distal stimulation, without significant temporal dispersion.
36
Axon loss lesion
Wallerian degeneration, which is typically completed in 7 to 10 days from the injury. After 10 days, the distal axon degenerates and can no longer conduct.Once denervation occurs, spontaneous muscle activity appears on EMG, manifested by fibrillation potentials, which usually appear after the third week from the injury.
37
GBS resp vitals
negative inspiratory force of less than −30 cc H2O or vital capacity of less than 15 to 20 mL/kg support elective endotracheal intubation.
38
Brachial plexus
C5 to T1 nerve roots
39
Roots
Two nerves that innervate the upper extremity branch off the nerve roots themselves. The dorsal scapular nerve, which innervates the rhomboids and levator scapulae, arises from the C5 nerve root. The long thoracic nerve, which innervates the serratus anterior, arises from the C5 to C7 roots.
40
Trunks
The ventral rami of the C5 to T1 nerve roots join to form the trunks of the brachial plexus. The upper (or superior) trunk, formed from the C5 and C6 nerve roots, gives off two branches: the suprascapular nerve, which innervates the supraspinatus and infraspinatus, and the nerve to subclavius. The point where the C5 and C6 nerve roots meet is called Erb’s point. The middle trunk is formed from the C7 root. There are no branches from the middle trunk. The lower (inferior trunk) is formed from the C8 and T1 roots. There are no branches from the inferior trunk. The trunks then divide into anterior and posterior divisions.
41
Cords
lateral cord gives rise to the lateral pectoral nerve, which innervates the pectoralis major. The lateral cord ends as two nerves, the median nerve and the musculocutaneous nerve. posterior cord ends as two nerves, the axillary nerve and radial nerve. The medial cord gives fibers to the median nerve and then continues as the ulnar nerve
42
familial amyloid polyneuropathy (FAP) type 1
polyneuropathy, autonomic features, and a family history.
43
familial amyloid polyneuropathy (FAP) type 2
carpal tunnel, a family history of carpal tunnel, mild predominantly sensory polyneuropathy, and absence of prominent autonomic features.
44
FAP 4
corneal dystrophy being a prominent early feature. In later life, cranial neuropathies and skin changes occur; cranial nerves VII, VIII, and XII are commonly affected.
45
FAP 3
FAP3 is similar to FAP1 in clinical manifestations, but with earlier renal involvement and more gastrointestinal involvement, with a higher incidence of duodenal ulcers.
46
FAP pathology
mutations in transthyretin, a plasma protein that is synthesized predominantly in the liver and transports thyroxine and other proteins.
47
Autonomic dysfunction resulting from diabetic neuropathy
resting tachycardia or bradycardia, loss of the respiratory variability of the heart rate, loss of the normal tachycardic response, orthostatic hypotension, and increased risk of silent myocardial infarction. Gastrointestinal abnormalities, Neurogenic bladder, impotence
48
Charcot–Marie–Tooth disease
hereditary sensorimotor neuropathies or peroneal muscular atrophy. group of inherited peripheral neuropathies. The CMTs can be divided into demyelinating, axonal, and combined demyelinating and axonal forms.
49
(CMT) 1
MT1A is due to a duplication in the peripheral myelin protein 22 (PMP22) gene on chromosome 17 related to myelin synthesis. hammertoes, high-arched feet, palpably enlarged nerves, two decades of life and include slowly progressive weakness, muscle atrophy, kyphosis. CMT 3 presents in infancy.
50
Median nerve arm
is derived from the lateral and medial cords. innervates pronator teres, flexor carpi radialis, and flexor digitorum superficialis. median nerve is prone to injury with supracondylar fractures.
51
Median nerve forarm
In the forearm, the median nerve gives off the anterior interosseous nerve that innervates flexor digitorum profundus to the second and third digits, flexor pollicis longus, and pronator quadratus
52
Median nerve wrist
Before entering the carpal tunnel, the median nerve gives off the palmar cutaneous sensory nerve, a pure sensory nerve. The median nerve then passes through the carpal tunnel and gives off the thenar motor branch, which innervates abductor pollicis brevis and opponens pollicis. The median nerve also innervates the first and second lumbricals.
53
Ulnar nerve
provides innervation to many intrinsic hand muscles.
54
Lumbar plexus
is formed by contributions from T12 to L4 and gives rise to three major and three minor nerves. Three minor nerves are the iliohypogastric, ilioinguinal, and genitofemoral. Three major nerves are the femoral, obturator, and lateral femoral cutaneous
55
Genitofemoral N.
L1 and L2.
56
Lateral femoral cutaneous nerve
L2 and L3
57
Femoral nerve
L2, L3, and L4
58
Obturator nerve
originates from the anterior divisions of L2, L3, and L4 and divides into an anterior and a posterior division.
59
lumbosacral trunk
is a structure that originates from L4 and L5 and joins the sacral plexus to form the sciatic nerve
60
Sacral plexus
originates from the L4-S4 nerve roots, with L4 and L5 provided by the lumbosacral trunk The anterior divisions of L4-S3 contribute to form the tibial division of the sciatic nerve. The posterior divisions from L4-S2 contribute to the common peroneal division of the sciatic nerve.
61
superior gluteal nerve
originates from L4, L5, and S1 and innervates the gluteus medius, gluteus minimus, and tensor fasciae latae.
62
Pudendal nerve
originates from S2, S3, and S4 and provides sensory innervation to the perineal region and perianal region through the inferior rectal nerve, perineal nerve, and dorsal nerve of the penis or clitoris
63
hereditary neuropathy with liability to pressure palsies (HNPP)
autosomal dominant predominantly demyelinating hereditary neuropathy with incomplete penetrance and is caused by a deletion in the peripheral myelin protein 22 gene (PMP22). Present with recurrent episodes of focal mononeuropathies or plexopathies of the upper or lower limbs; the peroneal nerve is most commonly affected, followed by the ulnar nerve
64
Hereditary neuralgic amyotrophy (Parsonage–Turner)
recurrent upper extremity mononeuropathies
65
Sciatic nerve
originates from the L4-S3 roots. Superior gluteal nerve innervates the gluteus medius, minimus, and tensor fasciae latae. The inferior gluteal nerve innervates the gluteus maximus
66
Sciatic nerve transitions to ?
tibial nerve medially and the common peroneal nerve laterally. short head of the biceps femoris is supplied by the common peroneal division which is above common site of compression.
67
Peroneal nerve
Superficial peroneal nerve gives off branches to the peroneus longus and brevis, which permit foot eversion. The deep peroneal nerve supplies the tibialis anterior, extensor hallucis, extensor digitorum longus and brevis, and peroneus tertius.
68
Deep peroneal nerve lesion
Foot drop with inability to dorsiflex the foot without impairing eversion of the foot. Preservation of foot inversion distinguishes peroneal neuropathy from L5 radiculopathy, in which the tibialis posterior muscle innerverated by tibialis N.
69
Femoral nerve injury
weakness in hip flexion and knee extension, loss of the patellar reflex, and sensory findings in the anteromedial thigh and medial leg.
70
Weak hip flexion?
Iliopsoas intrapelvic injury rather than an inguinal injury.
71
obturator nerve injury
adductor weakness suggests involvement L2-L4 radiculopathy or a lumbar plexopathy.
72
Anti-Hu
sensory neuronopathy (dorsal root ganglionopathy) in setting of SCC
73
Anti-Yo
is present in ovarian carcinoma and manifests with cerebellar degeneration
74
Anti-Ri
is associated with opsoclonus–myoclonus with or without ataxia in the setting of neoplasms of the lung or breast.
75
Anti-MAG
antibodies against myelin-associated glycoprotein and are associated with demyelinating neuropathy in the setting of MGUS
76
Sural nerve
tibial nerve gives off the sural nerve that provides sensory innervation to the lateral aspect of the leg and foot
77
Tibial nerve at level of thigh?
division of the sciatic nerve, and at the level of the thigh, it provides innervation to the semimembranosus, semitendinosus, and long head of the biceps femoris
78
Tibial nerve distal to popliteal fossa?
continues down the leg innervating the gastrocnemius, soleus, tibialis posterior, flexor digitorum longus, and flexor hallucis longus and splits up into sural nerve
79
Tibial nerve at the ankle?
tibial nerve passes under the flexor retinaculum through the tarsal tunnel and gives three terminal branches: (1) calcaneal, (2) medial plantar, and (3) lateral plantar.
80
Tarsal tunnel neuropathy?
entrapment neuropathy of the tibial nerve at the level of the tarsal tunnel will not produce weakness on plantarflexion. This entrapment neuropathy may manifest with burning pain in the plantar region, worse with standing and walking, with sensory deficits in the sole and sometimes atrophy in this area.
81
multifocal motor neuropathy (MMN)
purely motor demyelinating neuropathy that presents with asymmetric weakness from involvement of individual peripheral nerves, hypo- or areflexia in the distribution of affected nerves, and no sensory manifestations. Anti-GM1 antibodies
Rx IVIG, not plasmapharesis or steroids
82
Ulner nerve
continuation of medial cord. C8 and T1 fibers. branches to flexor carpi ulnaris and then flexor digitorum profundus to the fourth and fifth digits. Deep motor branch innervates hypothenar eminence muscles: abductor digiti minimi, flexor digiti minimi, and opponens digiti minimi
83
CMT4
autosomal recessive forms of Charcot–Marie–Tooth
84
S1 radiculopathy
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. weakness is plantarflexion and toe flexion, and the ankle deep tendon reflex will be reduced or absent. H-reflex is commonly reduced or absent.
85
ulnar neuropathy at or above the elbow
loss of fine motor coordination due to weakness of the third and fourth lumbricals, palmar/dorsal interossei. Claw hand, with the fourth and fifth digits hyperextended at the metacarpophalangeal joint and partially flexed at the interphalangeal joint and fourth lumbricals as well as the interossei and flexor digiti minimi are weak
86
Ulnar nerve compression at the wrist/Guyon’s canal
Involvement of flexor carpi ulnaris and flexor digitorum profundus. CMAP amplitudes would be abnormally low with stimulation at the wrist, and a reduction in CMAP amplitude would not occur with more proximal stimulation.
87
Diabetic amyotrophy
polyradiculoneuropathy. Onset occurs during adjustment of insulin treatment, or associated with episodes of hypo- or hyperglycemia. Develop weakness and eventually atrophy, which involve the pelvic girdle and thigh muscles.
88
Radial nerve
continuation of the posterior cord. C5, C6, C7, and C8 fibers. brachioradialis (a forearm flexor), and extensor carpi radialis longus and brevis. Distal to the elbow, it bifurcates into the posterior interosseous nerve innervates extensor carpi ulnaris, extensor digitorum communis, extensor digiti minimi, abductor pollicis longus, extensor pollicis longus and brevis, and extensor indices.
89
Foot drop
Foot drop can be seen with common or deep peroneal lesions, as well as with sciatic nerve lesions, L5 radiculopathies, and plexopathies. weak dorsiflexion and eversion points toward a common peroneal nerve injury. short head of the biceps femoris is spared suggests lesion is distal
90
lateral femoral cutaneous nerve
L2 and L3, and is purely sensory
91
Small-fiber neuropathy
preservation of vibratory sense and proprioception, as well as deep tendon reflexes/strength
92
posterior interosseous nerve palsy
pure motor nerve. Caused by diabetic mononeuropathy and posterior interosseous nerve compression (such as due to lipomas or nerve sheath tumors) or can be seen in Parsonage–Turner syndrome. Weakness of wrist extension in an ulnar direction
93
L2-L3-L4 radiculopathies vs lumbar plexopathy vs femoral nerve neuropathy
In radiculopathies, the SNAPs are normal, whereas in plexopathies, they are abnormal. Paraspinal fibrillations are seen in radiculopathies, but not in plexopathies. In femoral neuropathy, the manifestations should be restricted to the distribution and muscles supplied by this nerve.
94
Neuralgic amyotrophy or Parsonage–Turner syndrome
can occur following surgery, vaccination, or systemic viral illness; acute onset of severe shoulder and arm pain, which then resolve, with subsequent occurrence of weakness potentially affecting any part of brachial plexus
95
median nerve palsy at the level of the antecubital fossa
Intact strength of the ulnar nerve–innervated muscles indicates it is not a medial cord lesion
96
Ischemic monomelia
during placement of arteriovenous shunts for dialysis, is painful and causes circumferential sensory loss in multiple nerve distributions
97
anterior interosseous nerve syndrome.
pure motor branch of the median nerve and innervates flexor digitorum profundus to the second and third digits, flexor pollicis longus, and pronator quadratus
98
Demyelination on EMG
Typically show prolonged or abnormal distal latencies and slow conduction velocities, with abnormal late responses, which are the F-response and the H-reflex. Reduction in CMAP amplititude. Also motor conduction block
99
Pronator teres syndrome
compression of the median nerve as it passes between the two heads of pronator teres. pronator teres strength is intact and excludes a complete median nerve palsy at the elbow.
100
radial neuropathy at the axilla.
Loss of sensation over the posterior arm (posterior cutaneous nerve), weakness of the triceps. prolonged crutch use, or with prolonged pressure otherwise on the axilla, as occurs in “Saturday night palsy,”
101
radial neuropathy at the spiral groove
Intact strength of the triceps and intact sensation on the posterior aspect of the arm support that the lesion is distal to origin of the posterior cutaneous nerve to the arm and branches to triceps
102
Jugular foramen syndrome,
compressive lesions of the foramen magnum, such as metastases or schwannomas. Vagus/glossopharyngeal nerves, spinal accessory nerve
103
cervical plexus
ventral rami of C1 to C4. levator scapula (C3 and C4). greater/lesser occipital nerves
104
multifocal acquired demyelinating sensory and motor neuropathy (MADSAM)
demyelinating neuropathy with evidence of conduction block, presenting with asymmetric motor and sensory symptoms. Subacute progression usually starts off in the upper limbs --> lower limbs. anti-GM1 antibodies are not present.
Rx Steroids
105
superficial sensory radial neuropathy or Wartenberg’s syndrome
compression or irritation of superficial sensory radial neuropathy due to tight handcuffs or watches, venipuncture, or surgery
106
musculocutaneous neuropathy
continuation of the lateral cord and carries predominantly C5 and C6 fibers. innervates the brachialis muscle and the biceps brachii, which flex the forearm at the elbow. sensory innervation to the lateral half of the forearm via the lateral antebrachial cutaneous nerve, but this nerve does not provide any sensation below the wrist
107
Small-fiber neuropathy dx
diagnosis include quantitative sudomotor axon-reflex test (QSART), thermoregulatory sweat test (TST), and skin biopsy. EMG/NCS are normal because these tests evaluate the integrity of large nerve fibers.Small fibers include myelinated A-δ and unmyelinated C-fibers
108
QSART
evaluates postganglionic sympathetic cholinergic sudomotor function, and is performed by stimulation of sweat glands by iontophoresis of acetylcholine
109
thermoregulatory sweat test (TST)
assesses the pattern of sweating and dysfunction of sweating by placing the patient in a warming chamber while covered by a reactive powder that changes color with sweat. In small-fiber neuropathy with distal involvement, abnormal sweating is typically detected in hands and feet but not in the trunk.
110
Axillary neuropathy
fractures at the surgical neck of the humerus and with anterior shoulder dislocations. axillary nerve is a continuation of the posterior cord, and carries predominantly C5 and C6 fibers.
111
Fabry’s disease
X-linked disorder that results from a deficiency in the enzyme α-galactosidase A, a lysosomal enzyme. Commonly involved organs include the kidneys, heart, and skin. small-fiber neuropathy and autonomic neuropathy.
112
suprascapular nerve entrapment
shoulder pain, and weakness of the supraspinatus, which abducts the arm, particularly during the first 30 degrees of abduction, and infraspinatus, which externally rotates the shoulder when the elbow is flexed and fixed at the patient’s side.
113
thoracodorsal nerve
arises from the posterior cord and innervates the latissimus dorsi, which acts to adduct the arm.
114
thoracoabdominal polyradiculopathy
long-standing diabetes, and presents with pain and dysesthesias, patchy sensory and motor changes in thoracic and abdominal nerve root territories, usually unilateral but may be bilateral.
115
neurogenic thoracic outlet syndrome
compression on the C8 and T1 nerve roots. brachial plexus passes through the scalene triangle, which is formed by the anterior scalene, middle scalene, and first rib. Causing weakness of intrinsic hand muscles and sensory loss in a C8 and T1 distribution
116
hereditary sensory and autonomic neuropathy (HSAN) type 1
Starts in adulthood. including pain, sensory loss, and autonomic features with little motor involvement. The main autonomic manifestation is hypohidrosis
117
HSAN2
infancy, and is characterized by generalized loss of sensation and insensitivity to pain, leading to significant risk of mutilation to the hands, feet, lips, and tongue. Autonomic symptoms are not prominent
118
HSAN3 (familial dysautonomia)
autosomal recessive HSAN with prominent autonomic features. With emotional stimulation, there is hyperhidrosis, skin flushing, and hypertension. Other autonomic features include absence of lacrimation.
119
HSAN4
congenital insensitivity to pain. insensitivity to pain, leading to repeated injury and self-mutilation. Cognitive delay is also present, as are significant behavioral problems including hyperactivity. Autonomic features include anhidrosis, leading to heat intolerance and frequent fevers.
120
primary erythromelalgia
episodes of severe burning and erythema of the distal extremities, precipitated by exposure to either heat or cold. sodium channel SCN9A gene, which results in hyperactivity of the dorsal root ganglia.
121
lower trunk lesion
lead to weakness in ulnar and median nerve–innervated muscles.weakness of intrinsic hand muscles and sensory loss on the medial forearm and hand. Sensory loss occurs in a C8 and T1 distribution; the medial arm, innervated predominantly by T1 and T2, often has preserved sensation.
122
lateral cord lesion
weakness of musculocutaneous-innervated muscles as well as C6- and C7-innervated median nerve muscles
123
acute intermittent porphyria (AIP)
Common triggers include medications, menstruation, and alcohol exposure. With exposure to these triggers, activity of the hepatic enzyme ALA synthase increases, leading to overproduction of heme precursors. Neuropsychiatric symptoms including psychosis occur, and seizures. Wrist drop. During an attack, elevated levels of porphobilinogen and aminolevulinic acid are detectable in the urine and serum.
124
L5 radiculopathy
pain from the buttock radiating down the lateral thigh, anterolateral leg, and dorsum of the foot, with sensory impairment in this dermatomal region extending to the big toe. The weakness is prominent on toe extension and ankle dorsiflexion, as well as inversion and eversion of the foot. foot drop is a frequent manifestation that may be seen with L5 root lesion and common peroneal neuropathy distinguishing the two is NCS. Superficial peroneal SNAPs are abnormal in common peroneal nerve lesions, but normal in L5 radiculopathies.
