Arteriovenous malformations

Arteriovenous malformations

Vascular malformations

1-AVM(Arteriovenous malformations)
2-Cavernous hemangiomas
3-Venous angiomas
4-Capillary telangiectasias

Arteriovenous malformations

Definition:represent an aberrant connection between the arterial and venous circulation with bypass of the capillary system .

AVM
This network of abnormal connections represents the "nidus"
AVM
Feeding arteries in the arteriovenous malformation consist of a high blood flow due to low resistance within the arteriovenous malformation.(no capillaries)
low resistance is thought to result in ischemic events, or the Steal phenomenon.
Steal phenomenon
Shunting of blood away from a nervous system location causing transient or persistent ischemia or infarction.

Yamada S, Cojocaru T. Arteriovenous malformations. In: Wood JH, editor. Cerebral blood flow: physiologic and clinical aspects. New York: McGraw-Hill, 1987:580-90.

Hoffman WE. Brain tissue oxygenation in patients with cerebral occlusive disease and arteriovenous malformations. Br J Anaesth 1997 Feb;78(2):169-71.




AVM
Etiology:
Most often these malformations are due to congenital anomalies
Other etiologic include
trauma
radiation.

AVM
Time course-Location:

Arteriovenous malformations evolve slowly over many years and can occur in any location
most often in MCA distribution and in the parietal or frontal lobes.

AVM
Female-male
Commonly present in 2nd and 3rd decade
tangle of dilated veins, filled with arterialized blood ("red veins") is evident, as is hyperemia of the cortical surface
AVM
Hemosiderin deposits :
Adjacent to the AVM can frequently be observed, even in patients who have no history of hemorrhage, indicating that blood leakage is common.
fibromuscular dysplasia and thrombosis

Clinical manifestations
most common presentation for AVM ?

?
3 cm
Hemorrhage typically occurs in arteriovenous malformations <>3 cm
AVM AND HEMORRHAGE
AVM and hemorrhage
Risk of hemorrhage in patients diagnosed with arteriovenous malformations who have not had a previous hemorrhage is in the range of 1.3% to 3.9% yearly
53% of patients with arteriovenous malformations will experience a hemorrhage
Hofmeister C, Stapf C, Hartmann, Stroke 2000 Jun;31(6):1307-10. Demographic, morphological, and clinical characteristics of 1289 patients with brain arteriovenous malformation.


AVM and hemorrhage

SAH
intraparenchymal
Small leaks (hemosiderin deposits)

Factors that Contribute to Increased Risk of Hemorrhage from an Arteriovenous Malformation
Clinical factors
History of hypertension
History of previous hemorrhage
Factors that Contribute to Increased Risk of Hemorrhage from an Arteriovenous Malformation
AVM and hemorrhage
Comparison of Risk Factors and Annual Risk of Hemorrhage Stroke 1996 Jan;27(1):1-6


AVM AND SEIZURE
3 cm
Seizures typically accompany arteriovenous malformations >3 cm
hemorrhage typically occurs in arteriovenous malformations <>6cm 3p
Eloquence of location,1p noneloquence 0
Deep Venous drainage present 1
Grades 1 to 3 are typically treated with microsurgery
Unruptured AVM
Higher grades AVM are more challenging and require multidisciplinary approach for treatment .
Embolization (not used grade1-3)
Stereotactic radiosurgery

SEIZURE
Treatment of lesions presenting with seizures includes surgical resection, embolization, radiosurgery, and anticonvulsant therapy.
SEIZURE
3 year minimum follow-up who had AVM and preoperative seizures, revealed
83% of patients who underwent AVM resection were seizure free (with 48% no longer receiving anticonvulsant therapy),
17% still suffered intermittent seizures
Seizure outcome in patients with surgically treated cerebral arteriovenous malformations. Piepgras , J Neurosurg 1993 Jan;78(1):5-11
Bradly: Ogilvy et al 2001,succ
AVM and Pregnancy
?
AVM and Pregnancy
Bradely:
ICH by AVM is as common as ICH with aneurysems
Time dosen’t always correlate with peak cardiovascular changes
Labor is highest risk period
Descision about Tx should be base on Neurosurgical rather Obstetric criteia

AVM and Pregnancy
Bradley:
Risk of rebreeding is higher in pregnancy
Elective cesarean section may carry the lowest risk
Cavernous hemangiomas
seizure is the most common presentation (in contrast in AVM hemorrhage)38% to 100% of patients
Focal neurologic deficits are the second most common clinical manifestation and have been reported to present in 15.4% to 46.6% of patients.
The incidence of hemorrhage has been estimated from a low of 0.1% to 1.1%
Venous angiomas
Seizures are the most common type of presentation in venous angiomas.
The overall rate of bleeding in venous angiomas has been reported to be between 1% and 16%
Infratentorial and deeply draining supratentorial have a higher incidence of hemorrhage and rebleeding than do superficial supratentorial venous angiomas
Venous angiomas most often occur in the subcortical areas of the frontal lobe or cerebellum

Syndrome of continues motor unit activity

Syndrome of continues motor unit activity

Neuromyotonia


Neuromyotonia and myokymia


• The terms “neuromyotonia” and “myokymia” have both been used to describe “clinical phenomena” as well as distinct patterns of abnormal “electrical discharge” recorded during needle electromyography.

Neuromyotonia and myokymia
•This dual nomenclature has created confusion over the years, but no other set of clearer definitions has yet been universally accepted.

Neuromyotonia and myokymia

Both are related clinical phenomena that
result from hyperexcitability of peripheral
nerve motor axons.

Neuromyotonia and myokymia
•Whether they are really separate and distinct clinical entities or just reflect a difference in the severity of the same underlying electrophysiological abnormality remains undetermined.

Neuromyotonia and myokymia
Both may occur in a generalized or focal
fashion and reflect a generalized or
focal alteration in the microenvironment
or membrane of the peripheral nerve.


•Both clinical neuromyotonia and clinical myokymia are also classified as syndromes of continuous motor unit activity.



EMG Characteristics of Neuromyotonia

EMG Characteristics of Neuromyotonia
•Single MUAP firing rapidly
•150 Hz to 300 Hz discharges in long trains
•Trains occur at random intervals
•Train duration up to several seconds
•Decrementing train , Trains start and stop abruptly
•

EMG Characteristics of Myokymia
•Single MUAP firing as bursts of multiplets
•30 Hz to 40 Hz discharges in short bursts
•Burst occur at 2 Hz to 10 Hz
•Burst duration is 100 ms to 900 ms
•Semi-rhythmic burst pattern
•Bursts start and stop abruptly
Neuromyotonia
•is a syndrome marked by prominent and continuous muscle twitching and stiffness

• typically resulting from neuromyotonic and myokymic discharges.


Neuromyotonia
appear in adolescence and adult years. Diagnosis rests on both the clinical manifestations and typical electrophysiologic findings. Features of clinical neuromyotonia include:
Neuromyotonia
•clinical pseudomyotonia (slow muscle relaxation after a forceful contraction)
•contractures of the hands and feet (carpopedal spasms)
•Muscles of the limbs and trunk are stiff and rigid.

Clinical neuromyotonia
•Stiffness is more pronounced in the distal than proximal muscles, and it is worsened by exercise, although it may improve transiently with repetitive movement. Posture may be abnormal with exaggerated kyphosis, and movement is stiff and slow.

•Weight loss is common. The muscles may be well-developed, and sweating may be prominent, possibly because heat is generated by the excessive and constant muscle activity


ptosis, baldness, and temporalis muscle atrophy, cataractsTrinucleotide repeats , CTG .delayed muscle relaxation called myotoniapercussion."dive-bomber" activity that is the EMG hallmark of the disease.


•Dyspnea may result from tightening of the respiratory muscles. Bulbar and laryngeal muscles may be affected. The tongue and jaw become stiff, making swallowing difficult, and the voice turns hoarse
This abnormal activity persists during sleep .

•Focal neuromyotonic syndrome

•Morvan syndrome :
Acompanied with: confusion, insomnia, and hallucinations .

•Ocular neuromyotonia:
Includes intermittent diplopia produced by spasms of the extraocular muscles that occur spontaneously or in response to sustained eccentric gaze.



Physical examination
•Carpopedal spasms with flexion of the wrist, extension of the fingers, and plantar flexion of the feet .
•In clinical neuromyotonia demonstrates normal or depressed tendon reflexes, sometimes with coexisting sensorimotor peripheral neuropathy.
Laboratory studies
May demonstrate serum antibodies to voltage-gated potassium channels as well as mildly increased serum potassium . Oligoclonal bands have been reported in the cerebrospinal fluid .
Etiology
•Clinical neuromyotonia, in most cases, is autoimmune and sporadic .
•Many cases remain idiopathic
•A minority of neuromyotonic syndromes are hereditary and occur with some of the inherited neuropathies ( like the axonal variant of Charcot-Marie-Tooth disease).


•Antivoltage gated potassium channel antibodies are found in 40% to 50% of patients with acquired clinical neuromyotonia .(Vincent 2000; Gutmann 2001a; Van Parijs et al 2002)


•Clear association with thymoma, myasthenia gravis, lung cancer, and neuronal ganglionic antiacetylcholine receptor antibodies. (Vernino et al 1998; Hart et al 2002)


•Clinical neuromyotonia may also appear as a consequence of intoxication with mercury, penicillamine and oxaliplatin.

•Paraneoplastic syndromes of clinical neuromyotonia with hypernephroma and thymoma have also been reported, along with peripheral neuropathy, in bronchogenic carcinoma .
Treatment
•The clinical neuromyotonic syndromes may respond to immunomodulatory treatment including plasmapheresis, intravenous immunoglobulin, and steroids.

Treatment
•Neuromyotonia can sometimes be suppressed with phenytoin, carbamazepine, and dantrolene.
•In some patients, treatment can eventually be discontinued without recurrence , whereas others require life-long therapy.









•Clinical myokymia, in contrast, most commonly occurs as a component of other serious disorders .




•Focal myokymia may be caused by multiple sclerosis, pontine tumors, Guillain-Barré syndrome, radiation plexitis, and, rarely, rattlesnake envenomation. Facial myokymia may also be seen in Bell palsy, syringobulbia, polyradiculoneuropathy, central pontine myelinolysis, tuberculoma, meningeal carcinomatosi, meningeal sarcoidosis, lymphocytic meningoradiculitis, basilar invagination, phosgene poisoning, and hemifacial spasm. Facial myokymia can also occur spontaneously after brain death.






• Limb myokymia occurs in chronic inflammatory demyelinating polyneuropathy, rare compressive neuropathies, syringomyelia, spinal stenosis, conus medullaris teratoma, radiculopathy, neurocysticercosis, subarachnoid hemorrhage, and following cardiopulmonary arrest.


•Generalized myokymia may appear as a part of clinical neuromyotonia, restless leg syndrome, cramp fasciculation syndrome, gluten-sensitive enteropathy, and with clozapine use.