Flashcards in CN LANGE - Motor Disorders II Deck (101):
Investigation of patients with weakness of noncerebral origin - Electromyography - Spinal cord disorders + Anterior horn cell disorders + Peripheral nerve or plexus disorders:
1. Reduced number of motor units under voluntary control.
2. With lesions causing axonal degeneration, abnormal spontaneous activity (eg fasciculations, fibrillations) may be present if sufficient time has elapsed after onset.
3. With reinnervation, motor units may be large, long, and polyphasic.
Investigation of patients with weakness of noncerebral origin - Electromyography - NMJ disorders:
Often normal, but individual motor units may show abnormal variability in size.
Investigation of patients with weakness of noncerebral origin - Electromyography - Myopathies:
1. Small, short, abundant polyphasic motor unit potentials.
2. Abnormal spontaneous activity may be conspicuous in myositis.
Investigation of patients with weakness of noncerebral origin - Nerve conduction velocity:
Spinal cord disorders --> N.
Anterior horn cell disorders --> N.
Peripheral nerve or plexus disorders --> Slowed, especially in demyelinative neuropathies. May be normal in axonal neuropathies.
NMJ disorders --> N.
Myopathies --> N.
Investigation of patients with weakness of noncerebral origin - Muscle response to repetitive motor nerve stimulation:
Spinal cord disorders --> N.
Anterior horn cell disorders --> N, except in rapidly progressive disease.
Peripheral nerve or plexus disorders --> N.
NMJ disorders --> Abnormal decrement or increment depending on stimulus frequency and disease.
Myopathies --> N.
Investigation of patients with weakness of noncerebral origin - Muscle biopsy:
Spinal cord disorders + Anterior horn cell disorders + Peripheral nerve or plexus disorders --> May be normal in acute stage but subsequently suggestive of denervation.
NMJ disorders --> N.
Myopathies --> Changes suggestive of myopathy.
Investigation of patients with weakness of noncerebral origin - Spinal MRI or CT myelography:
Spinal cord disorders --> May be helpful.
Anterior horn cell disorders --> Helpful in excluding other disorders.
Peripheral nerve or plexus disorders --> Not helpful.
NMJ disorders --> Not helpful.
Myopathies --> Not helpful.
Spinal cord disorders (myelopathy) - Can lead to ...?
Motor, sensory, or sphincter disturbances, or to some combination of these deficits.
Traumatic myelopathy - Although spinal cord damage may result from whiplash (recoil) injury, sever injury to the spinal cord usually related to ...?
Fracture-dislocation in the cervical, lower thoracic, or upper lumbar region --> Commonly associated with local pain.
MC site for traumatic spinal cord injury is in the ...?
Traumatic myelopathy - Total cord transection:
1. Results in immediate permanent paralysis and loss of sensation below the level of the lesion.
2. Reflex activity is lost for a variable period, but then increases.
Total cord transection - In the acute stage ("spinal shock"):
There is flaccid paralysis with loss of tendon and other reflexes, accompanied by sensory loss + urinary/fecal RETENTION.
Total cord transection - Over the following weeks, as reflex function returns, ...?
1. A spastic paraplegia or quadriplegia emerges, with brisk tendon reflexes + extensor plantar responses.
2. However, a flaccid, atrophic (LMN) paralysis may affect muscles innervated by spinal cord segments AT THE LEVEL OF THE LESION, where anterior horn cells are damaged.
3. Sensation is reduced at that level + lost below it.
4. The bladder and bowel regain some reflex function, so that urine + feces are expelled at intervals.
Total cord transection - Flexor or extensor spasms of the legs ...?
May become increasingly troublesome and are ultimately elicited by even the slightest cutaneous stimulus, especially in the presence of bedsores or a urinary tract infection.
--> Eventually, the patient assumes a posture with the legs in FLEXION or extension, the FORMER being especially likely with cervical or complete cord lesions.
Traumatic myelopathy - Less severe injury:
With lesser injury, the neurologic deficit is less severe, but patients may be left with a mild paraparesis or quadriparesis +/- distal sensory disturbance.
Traumatic myelopathy - Less severe injury - Sphincter function:
May also be impaired - urinary urgency and urgency incontinence are especially common.
Traumatic myelopathy - Hyperextension injuries of the neck can lead to ...?
Focal cord ischemia that causes BIBRANCHIAL paresis (weakness of both arms) with sparing of the legs and variable sensory signs.
Traumatic myelopathy - Imaging - CT?
Sensitive for detecting spinal fractures, especially in the cervical region, and also allows evaluation of the spinal cord.
--> Preferred in the acute setting.
Traumatic myelopathy - Spinal MRI:
Provides complementary information about the extent and nature of any spinal cord injury and the presence of an EPIDURAL HEMATOMA, which is important in treatment and prognosis.
Traumatic myelopathy - Role of corticosteroids?
Traumatic myelopathy - Prognosis:
There is significant mortality after spinal cord injury, and this is highest in those with cervical injuries, associated head injury, cardiovascular or respiratory inadequacy, and coexisting disorders.
--> The greatest improvement is seen in those with incomplete injury, with most recovery occurring in the first few months.
MS - Epidemiology:
One of the MC neurologic disorders, affecting approx. 300.000 patients in the USA.
MS - Genetic predisposition:
1. Specific HLA alleles.
2. Alleles of IL2RA (IL-2 receptor alpha gene).
3. IL7RA (IL-7 receptor alpha gene).
MS - Pathology:
1. Development of focal - often perivenular - scattered areas of demyelination, together with reactive gliosis, axonal damage, and neuronal degeneration.
2. These lesions occur in BOTH white + gray matter of the brain and spinal cord + in the optic nerve.
MS - Pathophysiology:
The cause is unknown - Tissue damage and neurologic symptoms are thought to be triggered by an immune mechanism directed against myelin antigens.
MS - Several antigens may trigger the disease:
1. Myelin basic protein.
2. Myelin-associated glycoprotein.
3. Myelin oligodendrocyte glycoprotein.
4. Proteolipid protein.
MS - Clinical findings - Symptoms at presentation:
37% --> Paresthesia.
35% --> Gait disorder.
17% --> Lower extremity weakness or incoordination.
15% --> Visual loss.
10% --> Upper extremity weakness or incoordination.
10% --> Diplopia.
MS - Signs:
81% --> Absent abdominal reflexes.
76% --> Hyperreflexia.
57% --> Lower extremity ataxia.
54% --> Extensor plantar responses.
49% --> Impaired rapid alternating movements.
47% --> Impaired vibratory sense.
38% --> Optic neuropathy.
35% --> Nystagmus.
33% --> Impaired joint position sense.
32% --> Intention tremor.
31% --> Spasticity.
22% --> Impaired pain or temp. sensation.
19% --> Dysarthria.
17% --> Paraparesis.
11% --> Internuclear ophthalmoplegia.
MS - Clinical findings - Other patients present with an acute or gradually progressive spastic paraparesis and sensory deficit; this should raise concern about the possibility of ...?
An underlying structural lesion unless there is evidence on clinical exam of more widespread disease.
MS - Relapses may be triggered by ...?
Infection and, in women, are more likely in the 3 months or so after childbirth (but are reduced during the pregnancy itself).
A rise in body temperature can cause transient deterioration in patients with a fixed and stable deficit.
MS - Based on its course, the disease is divided into:
1. Relapsing-remitting form (85% of cases).
2. Secondary progressive form (80% of cases after 25yr).
3. Primary progressive form (10% of cases).
4. Progressive-relapsing form occurs rarely.
MS - Exam in advanced cases commonly reveals:
1. Optic atrophy.
4. UMN lesions.
5. Sensory or cerebellar deficits.
in some or all of the limbs.
MS - Investigative studies - CSF:
1. Mild lymphocytosis.
2. Slightly increased protein concentration, especially if examined soon after an acute relapse.
3. CSF protein electrophoresis shows the presence of discrete bands in the immunoglobulin G (IgG) region (oligoclonal bands) in 90% of patients --> The antigens responsible for these antibodies are unknown.
If clinical evidence of a lesion exists at only one site in the CNS, a diagnosis of MS cannot properly be made unless ...?
Other regions are affected subclinically.
Such subclinical involvement may be detected by the electrocerebral responses evoked by ...?
1. Visual evoked potentials --> Monocular visual stimulation with a checkerboard pattern.
2. Brainstem auditory evoked potentials --> Monaural stimulation with repetitive clicks.
3. Somatosensory evoked potentials --> Electrical stimulation of a peripheral nerve.
MRI may also detect subclinical lesions:
Has become nearly indispensable in confirming the diagnosis.
MRI findings - T1:
May reveal hypointense "black holes" that probably represent areas of permanent axonal damage; hyperintense lesions are also found.
--> Gadolinium-enhanced T1 images may highlight areas of inflammation with breakdown of the BBB.
MRI findings - T2:
Images provide information about disease burden or lesion load (ie total number of lesions), which typically appear as areas of high signal intensity.
The MRI of healthy subjects sometimes shows "unidentified bright objects" that resemble the lesions of MS but ...?
Are without clinical correlates or significance; the imaging findings must therefore be interpreted in the clinical context in which they were obtained.
Spinal MRI or CT myelography may be necessary to ...?
Exclude a single congenital or acquired surgically treatable lesion in patients with spinal involvement and no evidence of disseminated disease.
MS - Diagnosis - Requires:
Evidence that at least 2 different regions of the central white matter have been affected at different times.
MS can be diagnosed straightaway in patients with ...?
At least 2 typical attacks and 2 MRI lesions.
In patients with only one attack ...?
A further attack involving a different site suffices to show DISSEMINATION IN SPACE; otherwise, repeat imaging in a few months should demonstrate at least one T2 lesion in at least 2 of 4 typical sites.
The 4 typical sites of MS lesions:
To show DISSEMINATION IN TIME in a patient with only one attack, ...?
The simultaneous presence on MRI of asymptomatic gadolinium-enhancing + non-enhancing lesions at any time is sufficient.
--> Alternatively, it is necessary to await development of a new T2 or gadolinium-enhancing lesion on follow-up MRI or a 2nd clinical attack.
Diagnosis of primary progressive MS requires:
At least 1yr of progressive disease + 2 of the following:
1. At least one typical T2 brain lesion.
2. At least two spinal T2 lesions.
3. Positive CSF oligoclonal bands, increased IgG index, or both.
In patients with only a single clinical event and who do NOT satisfy criteria for MS, ...?
A CLINICALLY ISOLATED SYNDROME (CIS) is diagnosed.
Are at increased risk for developing MS and are sometimes offered treatment as if they has the disease in the hope of delaying progression to clinically definite disease.
CIS patients - Follow-up MRI should be considered ...?
6-12 months later to determine whether any new lesions have occurred.
Treatment of MS or clinically isolated demyelinating events suggestive of MS - Acute episode, including relapse:
1. Methylprednisolone, 1g IV daily x 3-5days.
2. Prednisone, 1g PO daily x3-5days.
3. Dexamethasone, 160mg PO daily x3-5days.
--> For corticosteroid-refractory relapses, plasmapheresis or IVIG may be used.
Treatment of MS or clinically isolated demyelinating events suggestive of MS - Relapse prevention, 1st-line treatment:
1. Interferon: β-1a (Rebif), 44μg SC 3x per week/ β-1a (Avonex), 30μg IM once per week/ β-1b (Betaseron), 0.25mg SC on alternate days.
2. Glatiramer acetate (Copaxone), 20mg SC daily.
3. Fingolimod (Gilenya), 0.5mg PO daily.
4. Teriflunomide (Aubagio), 14mg PO daily.
5. Dimethyl fumarate (Techfidera), 240mg PO 2x daily.
Treatment of MS or clinically isolated demyelinating events suggestive of MS - Relapse prevention for disease activity despite use of 1st line treatment:
1. Natalizumab (Tysabri), 300mg IV monthly.
2. Fingolimod, 0.5mg PO daily.
3. Teriflunomide (Aubagio), 14mg PO daily.
4. Dimethyl fumarate (Techfidera), 240mg PO 2x daily.
5. Mitoxantrone, 12mg/m^2 IV every 3 months; max lifetime dose, 140mg/m^2.
Treatment of MS or clinically isolated demyelinating events suggestive of MS - High disease activity (typically with multiple gadolinium-enhancing lesions on MRI):
Natalizumab (Tysabri), 300mg IV monthly.
A mixture of random polymers stimulating the amino acid composition of myelin basic protein.
An α4 integrin antibody, reduces the relapse rate when given IV monthly.
--> Rarely has been associated with PML.
MS - Prognosis - Features that tend to imply a more favorable prognosis include:
1. Female gender.
2. Onset before 40.
3. Presentation with visual or somatosensory, rather than pyramidal or cerebellar dysfunction.
MS - Prognosis - Although some degree of disability is likely to result eventually, ...?
Approx. 1/2 of patients are only mildly or moderately disabled 10yr after the onset of symptoms.
This relapsing disorder (formerly known as Devic disease) and once considered a variant of MS) is associated with a specific antibody marker, NMO-IgG, that targets the water channel aquaporin-4.
Neuromyelitis optica - Characterized by ...?
Optic neuritis + acute myelitis associated with MRI changes that extend over at least 3 segments of the spinal cord.
Neuromyelitis optica - Some patients with isolated myelitis or optic neuritis are also ...?
--> Seropositivity suggests a poor visual outcome.
Neuromyelitis optica - Unlike MS, the MRI typically ...?
Does NOT show widespread white matter involvement, although such changes do NOT exclude the diagnosis.
Acute disseminated encephalomyelitis (ADEM):
Neurologic symptoms and signs develop over a few days in association with a nonspecific viral infection, after immunization, or without obvious antecedents, when it then may represent the initial manifestation of MS.
ADEM - Pathologically:
Perivascular areas of demyelination are scattered throughout the brain and spinal cord, with an associated inflammatory reaction.
--> Lesions are all of similar age, and the brain appears swollen.
ADEM - Highest incidence?
ADEM - Initial symptoms:
4. Exam reveals meningeal irritation.
5. Multifocal neurologic deficits are common.
6. The patient is typically encephalopathic, with disturbances of consciousness that range from somnolence to coma, seizures may occur.
ADEM - Prognosis:
The neurologic deficit resolves spontaneously, at least in part, over a few weeks or months.
--> Many patients make a virtually complete recovery, but some are left with severe residual deficits.
--> Measles-associated disease is often especially SEVERE.
ADEM - MRI - T2:
Show asymmetric high-signal lesions particularly in the hemispheric white matter, optic nerves, basal ganglia, thalamus, cerebellum, brainstem, or spinal cord.
--> There may be mass effect and edema.
ADEM - MRI - T1:
Low-signal lesions are found in the white matter and - depending on their age - may enhance uniformly with gadolinium.
--> Gray matter abnormalities may also be present.
ADEM - DDx:
The diagnosis is based on the clinical and neuroimaging features.
3. Other inflammatory disorders (eg MS).
must be excluded.
--> Long-term follow-up helps to confirm the diagnosis.
Spinal epidural abscess - May occur as a sequel to ...?
1. Skin infection.
3. Vertebral osteomyelitis.
5. Spinal trauma or surgery.
6. Epidural anesthesia.
Spinal epidural abscess - Predisposing factors include:
2. Iatrogenic immunosuppression.
Spinal epidural abscess - MC causative organism:
3. Gram(-) bacilli.
Spinal epidural abscess - Neurologic complications result from ...?
1. Compression of the spinal cord or its blood supply.
2. Obstructed venous drainage.
3. Inflammatory reactions.
Spinal epidural abscess - Clinical findings:
2. Backache and tenderness.
3. Pain in the distribution of a spinal nerve root.
--> Followed by rapidly progressive paraparesis, sensory disturbances in the legs, and urinary/fecal RETENTION.
Spinal epidural abscess is a neurologic ...?
Spinal epidural abscess - Imaging study of choice?
MRI with gadolinium enhancement --> Should be sufficient to determine the extent of the abscess.
Spinal epidural abscess - Prognosis:
Delayed diagnosis or treatment and suboptimal management may lead to irreversible paraparesis or paraplegia, which occurs in up to 20% cases.
Spinal epidural abscess - The most important prognostic indicator is ...?
The patient's clinical status before decompressive surgery; the more severe the preoperative deficit, the less recovery is to be expected.
Acute transverse myelitis:
This syndrome results from a variety of infectious (bacterial, viral, fungal, parasitic) + noninfectious inflammatory disorders (MS, NMO, ADEM, systemic autoimmune diseases, idiopathic) --> That produce anatomic and functional disruption of the spinal cord.
Acute transverse myelitis - Who is affected most often?
Children and young adults.
Acute transverse myelitis - Clinical findings:
1. Bilateral sensory, motor, and autonomic deficits in the limbs and trunk.
2. A discrete sensory level corresponding to the site of inflammation in the spinal cord.
3. A course of hours to dayls.
4. An inflammatory CSF profile (pleocytosis; an accompanying low CSF glucose suggests an infective cause).
5. MRI showing an intrinsic spinal cord lesion that usually enhances with gadolinium administration.
Acute transverse myelitis - What must be excluded?
Compressive lesions of the spinal cord, such as spinal epidural abscess.
Acute transverse myelitis - Prognosis:
Patients tend to improve over several months, but may have residual deficits, and mortality rates in excess of 30% have been reported.
Can produce a meningovasculitis resulting in spinal cord infarction.
May lead to vertebral disease (Pott) with secondary compression of the spinal cord, meningitis with secondary arteritis and cord infarction, or cord compression by a tuberculoma.
AIDS - A disorder of the spinal cord, ...?
Vacuolar myelopathy, is found at autopsy in about 30% of patients with AIDS, in most of whom it was asymptomatic.
AIDS - Vacuolar myelopathy - Vacuolation of white matter in the spinal cord is most pronounced in ...?
The thoracic lateral + posterior columns.
AIDS - Vacuolar myelopathy - Although attributed to direct involvement of the HIV-1, the correlation ...?
Between the presence and extent of HIV-1 infection + spinal pathology is poor.
--> A metabolic basis is therefore suggested.
Myelopathy in patients with AIDS also may be caused by ...?
2. Cryptococcal infection.
Most patients with vacuolar myelopathy have ...?
Coexisting HIV-associated dementia.
AIDS - Vacuolar myelopathy - Symptoms progress over ...?
Weeks to months and include:
1. Leg weakness.
4. Erectile dysfunction.
--> There is typically NO BACK PAIN.
Tropical spastic paraparesis:
HTLV-1 appears to be the cause --> Found in Caribbean, off the Pacific coast of Colombia, and in the Seychelles.
Tropical spastic paraparesis - Features include:
1. Spastic paraparesis.
2. Impaired vibration.
3. Joint position sense.
4. Bowel and bladder dysfunction.
Tropical spastic paraparesis - A clinically similar myelopathy ...?
May also follow infection with HTLV-II.
Herpesviruses can also produce myelopathy:
Commonly affects the spinal nerve roots as well as the cord (radiculomyelopathy), especially in immunocompromised patients, such as those with AIDS.
CMV causes a myelopathy characterized by ...?
Demyelination of the posterior columns of the spinal cord and by cytomegalic cells that contain Cowdry type A inclusion bodies.
Tetanus - Prognosis:
Fatality rates of 10% to 60% are reported.
--> Among patients who recover, approx. 95% do so without long-term sequelae.
Chronic adhesive arachnoiditis:
This inflammatory disorder is usually idiopathic but can follow:
3. Intrathecal administration of penicillin, radiologic contrast materials, and certain forms of spinal anesthetic.
Chronic adhesive arachnoiditis - The usual initial complaint is of ...?
Constant radicular pain, but in other cases paresthesias or LMN weakness occur.
--> Eventually, a spastic ataxic paraparesis develops, with sphincter involvement and sexual dysfunction.