Supranuclear Lesions

Super Memory Formula

Memory Loss Cure Diet

Get Instant Access

Interruption of the corticobulbar tracts providing innervation of cranial nerve motor nuclei from the cerebral precentral motor cortex produces disturbances of speech, swallowing, chewing, and occasionally breathing known as pseudobulbar palsy. Patients with this disorder may also have emotional lability with exaggerated crying or laughter in response to minimal provocation. Because the ninth and tenth cranial nerve nuclei receive bilateral innervation, a unilateral lesion may be silent or may produce only mild symptoms. Supranuclear lesions are responsible for weakness of speech, chewing, and swallowing; the muscles do not also produce prominent atrophy because the lower motor neuron and its trophic effect on the muscle remain

TABLE 13-3 -- SELECTED ETIOLOGIES ASSOCIATED WITH DISORDERS OF CRANIAL NERVE XI AND CRANIAL NERVE XII

Etiological Category

Seleced Specific Etiologies

Chapter

STRUCTURAL DISORDERS

Developmental

Immaturity of cervical vagus nerve fibers

28

Degenerative compressive

Paget's disease

29

HEREDITARY AND DEGENERATIVE DISORDERS

The degenerative dementias

Bifrontal pathology, especially Alzheimers, Picks disease

33

Movement disorders

Adductor spasmodic dysphonia Abductor spasmodic dysphonia Parkinsonism

34

Degenerative motor, sensory and autonomic disorders

Amyotrophic lateral sclerosis

36

ACQUIRED METABOLIC AND NUTRITIONAL DISORDERS

Endogenous metabolic disorders

Neuropathy of glossopharyngeal afferent and vagus efferent fibers of circulatory reflexes especially diabetes

38

Nutritional deficiencies and syndromes associated with acoholism

Neuropathy of glossopharyngeal afferent and vagus efferent fibers of circulatory reflexes,poor nutrition, alcoholism

40

INFECTIOUS DISORDERS

Nonviral infections

Syphilis

42

NEUROVASCULAR DISORDERS

Strokes with bifrontal pathology (pseudobulbar paresis) Lateral medullary syndrome, postenor fossa, artenovenous malformation

45

NEOPLASTIC DISORDERS

Primary neurological tumors

Schwannoma

46

Metastatic neoplasms and paraneoplastic syndromes

Tumor to base of skull, nasopharynx, chest

47

DEMYELINATING DISORDERS OF THE PERIPHERAL NERVOUS SYSTEM

Guillain-Barre syndrome

49

AUTOIMMUNE AND INFLAMMATORY DISORDERS

Sarcoidosis

50

TRAUMATIC DISORDERS

Compromise of jugular foramen contents by basilar skull fracture

51

EPILEPSY

Intractable epilepsy

52

HEADACHE AND FACIAL PAIN

Glossopharyngeal neuralgia

53

DRUG-INDUCED AND IATROGENIC DISORDERS

Vincnstine

55

intact. Palate and gag reflexes remain intact, even heightened, and abnormal reflexes such as the snout and suck may be present, along with an increased jaw jerk reflex. Patients with pseudobulbar palsy may have dementia due to cerebral pathology involving bilateral frontal areas.

Acute onset of pseudobulbar palsy in one series of 13 patients was associated with infarction in the operculum, the internal capsule or corona radiata, or hemorrhage in lenticular nuclei. y Six of these patients had no prior history of stroke. Only one of these patients was described as having neuropsychological deficits, and all improved or recovered from the pseudobulbar symptoms within a few weeks.

Supranuclear innervation of speech is also derived from extrapyramidal pathways. Basal ganglia dysfunction is believed to be the source of focal dystonias involving the larynx causing adductor and abductor spasmodic dysphonia. y The former type is the far more common of the two. Involuntary adduction of the cords during phonation produces speech that has an interrupted, strangulated quality that is often effortful for the patient. In the less common abductor type of spasmodic dysphonia the patient has a breathy voice. As in other forms of focal dystonia, the patient may employ certain "tricks" to briefly overcome the dystonia, presumably by using other motor pathways to accomplish the desired movement. Some patients with spasmodic dysphonia may find their voice nearly normal when singing or shouting. These fluctuations of symptoms and ability to speak have in the past resulted in psychiatric diagnoses, leading to inappropriate and unproductive therapies and, when the correct diagnosis is established, a lingering resentment and hostility on the part of the patients toward physicians.

Symptomatic treatment of adductor dysphonia has been quite successful by injection of small amounts of botulinum toxin into the thyroarytenoid muscle of the larynx.y y y This technique is regarded by many as the treatment of choice for this disorder. Treatment of the abductor type of spasmodic dysphonia by botulinum toxin injection has been technically more difficult and has produced less satisfactory results, although some investigators have reported success targeting the posterior cricoarytenoid or the cricothyroid muscles. y , y

Unilateral stimulation of the vagal nerve has been studied as an adjunctive means to treat intractable partial epilepsy. y Electrodes from an implantable pacemaker device are attached to the left vagus nerve, and they provide intermittent stimulation. The mechanism of reducing seizures is believed to be by activating cortical and subcortical connections to the vagal nuclei.

Was this article helpful?

0 0
Cheat Sheet For Beeing Beautiful

Cheat Sheet For Beeing Beautiful

Start looking forward to your deserving easy beauty and less cash coming out of your pockets. Once you use this strategy, it will change the way you think about beauty products forever.

Get My Free Ebook


Post a comment