Flashcards in anterior horn, NMJ and muscle disease Deck (35):
Clinical generalization of neuromuscular disorder symptoms
all motor neuron, neuromuscular junction and muscle diseases have no sensory changes accompanying the weakness. Coexisting sensory complaints suggest a nerve root, plexus or peripheral nerve disorder.
Characteristics of neuromuscular junction disorders
Rapidly developing weakness (hours to days)- such as occurs in myasthenia gravis, botulism and organophosphate poisoning.
proximal weakness indicates which type of disorder
muscle disorders-difficulty in climbing stairs, arising from low chairs and elevating arms over the head. Their gait is broad-based, the posture lordotic and movement has a waddling appearance of the buttocks.
Distal weakness indicates which type of disorder
Distal weakness of hands and feet (often in association with distal sensory loss) is most characteristic of neuropathies. Patients have a slapping, foot-drop gait and a great deal of difficulty with fine hand movements
Cranial weakness indicates which type of disorder
myasthenia gravis- affects extraocular, facial and oropharyngeal muscles. Typical features include droopy eyelids (ptosis), dopuble vision and speaking and swallowing abnormalities.
Labs to test for neuromuscular disorders
1. Serum creatine kinase is elevated (due to muscle necrosis). 2. nerve conduction studies, needle electromyography, and repetitive nerve stimulation. 3. muscle/nerve biopsy. 4. genetic testing
Uses of electrodiagnostic studies
1. nerve conduction studies broadly differentiate between primary demyelinating (very slow NCS) and axonal neuropathies. 2. Needle EMG useful in differentiating myopathic from neuropathic disorders
Amyotrophic lateral sclerosis signs/symptoms
progressive weakness and wasting. Degenerating UMN causes spasticity and hyperreflexia. Initially, asymmetric limb weakness in the presence of fasciculations. A foot drop or marked hand deformity. Sensory exam normal
degeneration of brainstem and spinal cord lower motor neurons
ALS inheritance pattern
majority of cases are sporadic, although 5-10% are familial
Muscles involved in ALS
Extraocular and facial muscles are often spared. Onset usually in legs before arms. May spread along neuraxis. Diaphragm weakness and impaired swallowing produce fatal aspiration pneumonia.
medications for cramps, spasticity, excess saliva, and inappropriate laughing or crying. Riluzole extends life for 3 months. A feeding tube and positive pressure ventilation, either by mask or via tracheostomy, can extend life.
RX used for cramps/spasticity
Helps with jaw quivering/clenching- hydration, benzodiazepams, phenytoin, quinine, lioresal, dantrolene, gabapentin
Rx for pseudobulbar effects
tricyclic and SSRI antidepressants, dextromethorphan + quinidine.
Rx of drooling, thick phlegm & laryngospasm in ALS
decrease saliva: glycopyrrolate, amitriptyline, diphenhydramine, oxybutinin, scopalamine, artane, salivary gland irradiation. thick saliva: metoprolol, propanolol nasal congestion: decongestants, antihistamines
What is charcot marie tooth disease
Inherited neuropathies - type I(autosomal dominant) is demyelinating with slow nerve conduction velocities. Type 2 (autosomal dominant) has axonal degeneration with normal nerve conduction velocities. Type 4 is recessive. Each type has a letter for the gene causing the disorder
Charcot Marie Tooth Disease (CMT1A) genetics
duplication of the DNA containing the peripheral myelin protein gene PMP22
Charcot marie tooth phenotypes
1. onset of walking is normal but distal (hands and feet) weakness and sensory loss develops slowly in the first two decades of life. 2. already impaired as infants and experience delayed walking. Many are confined to wheelchairs later in life. 3. adult onset and may not appear until approximately 40 years of age
test use in CMT
nerve conduction velocity- The cutoff between demyelinating and axonal forms of CMT was established as 38m/sec
No medications to reverse the dz. Focus on improving quality of life with physical therapy, occupational therapy and orthopedic surgery
Diabetic sensory or sensorimotor distal polyneuropathy symptoms
A distal sensory or sensorimotor polyneuropathy is the most common type. numbness and burning dysesthesias in their feet which over time spreads up the legs and eventually into the hands. Weakness of foot dorsiflexor muscles results in a slapping foot drop gait. Grip strength and fine hand dexterity may be diminished
Small fiber vs large fiber pattern in polyneuropathy
A loss of position, vibration and light touch, as well as decreased reflexes, is prominent in `large fiber’ pattern. Relatively pronounced loss of pain and temperature sensation, in association with pain, indicates predominantly `small fiber’ injury. NCVs are often near normal if only small fibers are involved.
Diabetic Autonomic neuropathy symptoms
–Hypotension, diarrhea, impotence, urinary retention, sweating
Diabetic Mononeuropathy nerve targets
–Cranial nerve (3, 6,7) or peripheral (median- carpal tunnel, ulnar, peroneal)
Diabetic Lumbosacral plexopathy symptoms
–Pelvic girdle pain; asymmetric hip flexor weakness
pathogenesis of diabetic neuropathies
Metabolic derangements and changes in endoneural vessels with associated ischemia may be the primary cause. Mononeuropathies are from occlusion of small, nutrient blood vessels supplying the nerves
Treatment of diabetic polyneuropathy
Metabolic control, foot hygiene, pain management, Codeine/diphenoxylate for diarrhea, fluorocortisone/midodrine for hypotension, regular voiding for urinary retention
Myasthenia gravis symptoms
Ptosis, ophthalmoparesis, jaw and neck weakness, facial muscle weakness, trouble swallowing leads to aspiration, respiratory muscle weakness, limb muscle weakness is variable and not major manifestation. Thymic enlargement common, and thymomas can occur
Myasthenia gravis treatment
Symptomatic temporary benefit is obtained using oral cholinesterase inhibitors (pyridostimine). Corticosteroids reverse immune response (plus other immunosuppressive agents like azathioprine). Temporary (2-3 weeks) improvement with plasma exchange or IV IG infusion. Thymectomy recommended except in very young and old, to reduce adverse effects of meds (thymectomized patients need less immunosuppressive meds)
Duchenne/Becker dystrophy genetics
X-linked recessive disorders caused by a variety of deletions, duplications and point mutations in the area of the X chromosome coding for the membrane protein dystrophin
Duchenne vs Becker dystrophy
Becker dystrophy (BD) differs from Duchenne dystrophy (DUD) only in that the onset is usually later, the course is more benign, and survival is longer (into the 30s and 40s). Mental impairment is seen less often as well.
Duchenne dystrophy symptoms
clumsy waddling gait from the time they first walk, lumbar lordosis, pseudohypertrophy of calves, toe walking, difficulty rising from floor (Gowers maneuver). Respiratory muscles become weak plus kyphoscoliosis reduces pulmonary reserve and they usually die from respiratory/heart failure in 20s
Duchenne dystrophy diagnosis
Elevated serum CK, muscle biopsy and EMG show myopathic features (fibrosis, degeneration, opaque fibers), genetic test
Duchenne dystrophy treatment
Vigorous stretching reduces contractures early in disease, surgical release of lower extremity contractures, long leg braces, spinal fusion for scoliosis >40 degrees, BiPAP, full ventilation