MSD Ch 4 Flaccid Dysarthrias PDF

Flaccid Dysarthrias Caused by injury to one or more cranial or spinal nerves. Reflect problems in the nuclei, axons, or neuromuscular junctions that make up motor units in the FCP Primary distinguishing deviant characteristics: reduced muscle tone, muscle weakness, effects on speed, range, and...

Flaccid Dysarthrias Caused by injury to one or more cranial or spinal nerves. Reflect problems in the nuclei, axons, or neuromuscular junctions that make up motor units in the FCP Primary distinguishing deviant characteristics: reduced muscle tone, muscle weakness, effects on speed, range, and accuracy of movements. 10.1% of all dysarthrias, 9.6% of all MSDs. Can reflect involvement of a single muscle group (e.g., tongue) or an entire subsystem (e.g., phonation). All subtypes share a lesion somewhere between BS or SC & the muscles of speech. Share weakness and reduced tone as neuromuscular basis, and are considered problems of neuromuscular control NOT planning. Perceptually distinguishable from one another as a function of the specific cranial or spinal nerves that have been damaged. Clinical Characteristics of Flaccid Paralysis Flaccid paralysis reflects FCP damage Reflexive, automatic, and voluntary movements are all affected. Weakness, hypotonia, and diminished reflexes are the primary clinical characteristics, often accompanied by atrophy and fasciculations, and occasionally accompanied by rapid weakening with use and recovery with rest. Weakness: Stems from damage to any part of the motor unit (specifics in table 4.1 page 100 when book is big) Hypotonia and Reduced Reflexes: Hypotonia characterized by floppiness of muscle and reduced resistance to passive movement Flaccid paralysis affects stretch reflex which is impaired, resulting in flabbiness that can be seen or felt in muscles with reduced tone Atrophy When muscles are not uses, they eventually lose bulk, or atrophy Fasciculations and Fibrillations Fasciculations: visible, arrhythmic, isolated twitches in resting muscle, result from spontaneous motor unit discharges in response to nerve degeneration or irritation. Fibrillations: invisible, spontaneous, independent contractions of individual muscle fibers that reflect slow repetitive action potentials. Progressive Weakness with Use Occurs when disease affects neuromuscular junction Etiologies Can be caused by any process that damages the motor unit Congenital, demyelinating, infectious, inflammatory, degenerative, metabolic, neoplastic, traumatic, vascular Common terms Neuropathy: any disease of the nerve, but usually of noninflammatory etiology Neuritis: inflammatory disorder of nerve Peripheral neuropathy: any disorder of the nerves in the PNS (can affect motor, sensory or autonomic fibers, can be axonal, demyelinating, or mixed in effect) Cranial neuropathies: peripheral neuropathies affecting cranial nerves. Mononeuropathy: neuropathy of a single nerve Polyneuropathy: generalized process producing widespread bilateral and often symmetric effects on the PNS Radiculopathy: PNS disorder involving root of a spinal nerve, often just proximal to the intervertebral foramen Plexopathy: PNS involvement at the point where spinal nerves intermingle in plexuses before forming nerves that go to extremities Myelopathy: any pathologic condition of the spinal cord Myelitis: nonspecific term for inflammation of the SC Myopathy: muscle disease, not associated with sensory disturbances or CNS pathology, most common types affect proximal rather than distal muscles. Myositis: inflammatory muscle disease Some Associated Diseases and Conditions Degenerative Disease: Motor neuron diseases are a group of disorders involving degeneration of motor neurons ALS most common motor neuron disease (affects bulbar, limb, and respiratory muscles).. ALS is a UMN and LMN disease, but initial manifestations are sometimes confined to LMNs. Spinal muscle atrophies form a subgroup of hereditary LMN syndromes associated with progressive limb wasting and weakness. Some subtypes emerge during infancy or early childhood, but there is an adult onset form (SMA IV) emerging around 30-40. Affects only males.  Facial onset sensory and motor neuronopathy (FOSMN): recently described, rare, slowly progressive, probably neurodegenerative condition characterized by sensory symptoms in the face, followed by dysarthria, dysphagia, fasciculations, and atrophy consistent with LMN weakness. Trauma: Surgery can temporarily injure or perm damage cranial nerves, perhaps the most common cause of VF paralysis Procedures with known risk include carotid endarterectomy, anterior cervical spine surgery, BS vascular procedures, surgical resection for tumors in the posterior fossa, skull base, or cranial nerves CHI, skull fractures, neck injuries, etc. Muscle Disease: Muscular dystrophies (MDs) are a group of genetic skeletal muscle diseases associated with muscle fiber degeneration and replacement with fatty and fibrous connective tissue. Can occur in all ages, effects are diffuse, chronic, and progressive Congenital (Duchenne muscular dystrophy, X linked affecting boys) Myotonic muscular dystrophy is the most common form of MD in adults. Characterized by persistence of muscular contractions after stimulation or after forcible contraction has ceased, can manifest as delayed relaxation of the jaw or lips after clenching or pursing. Jaw and facial weakness gives face long and expressionless appearance with weak voluntary and emotional face movements. Vascular Disorders Any BS stroke that affects speech CN nuclei can lead to FD. Wallenberg’s lateral medullary syndrome: occlusion of intracranial vertebral artery or the posterior inferior cerebellar artery, leads to ipsilateral facial and contralateral trunk and extremity sensory loss, ipsilateral cerebellar signs, ipsilateral neuroophthalmologic abnormalities, ipsilateral nucleus ambiguus involvement with palatal, pharyngeal, and laryngeal weakness, and dysarthria and dysphagia. Tumor Skull base tumors can cause cranial neuropathies and flaccid dysarthrias Neurofibromatosis: autosomal dominant disease, reflects mutations in genes that influence tumor suppression. NF1 (more common form) produces neurofibromas and other tumors anywhere in NS, but commonly appearing on spinal and cranial nerves. NF2 leads to progressive hearing loss and bilateral acoustic neuromas as well as tumors of other cranial nerves Flaccid dysarthrias can occur with either NF type Neuromuscular Junction Disease MG is most common, has an incidence of 6 to 22 million, with incidence highest in women in the 3rd decade and men in the 6th and 7th decades. Autoimmune response against ACh receptors in the postsynaptic membrane, makes muscle less responsive to ACh, so contractions rapidly diminish with use, strength improves with rest. Frequent presenting signs include ptosis, facial weakness, flaccid dysarthria and dysphagia, in rare cases dysphonia is the only presenting speech complaint. MG frequently Dx’d in single-fiber EMG, ACh receptor antibody blood tests, or an edrophonium test. Infectious Processes Polio (poliomyelitis) is a contagious viral disease that can be prevented by immunization, has an affinity for LMN cell bodies, most often in the lumbar and cervical spinal cord Bulbar involvement predominates, CNs IX and X most often affected. Individuals with HIV who develop AIDS may develop neurologic complications as the result of opportunistic infections (e.g., cryptococcal meningitis is a common opportunistic infection) Encephalitis, meningitis, and meningoencephalitis sometimes affect BS areas, CN deficits and flaccid dysarthria can be among presenting symptoms in some cases. Demyelinating Disease Guillain-Barre syndrome is an acute, inflammatory, autoimmune, mostly demyelinating peripheral motor neuropathy that is frequently preceded by a flu like illness or infection. Anatomic Anomalies Chiari malformations are congenital abnormalities characterized by downward elongation of the brainstem and cerebellum through the foramen magnum into the cervical spinal cord. Syringomyelia is a formation of a fluid-filled cavity in the spinal cord, when it forms into the BS it is called a syringobulbia. Other causes: Sarcoidosis is a granulomatous disease of uncertain cause that can occur in any organ. Radiation therapy can cause cranial neuropathies and associated FD Cranial mononeuropathies (bell’s palsy, vocal fold paralyses) are frequently idiopathic. Speech Pathology Distribution of Etiologies in Clinical Practice  Cognitive impairment uncommon in individuals with FD. (7%) Patient Perceptions and Complaints Pts with FD offer complaints that differ from those associated with other dysarthria types Trigeminal Nerve (V) Lesions Damage to V is usually associated with involvement of other CNs. Rarely is it the only nerve affected in FD. Etiologies: aneurysm, infection, AVM, tumors in middle fossa or cerebellopontine angle, surgical trauma, or nonsurgical trauma to the skull or anywhere along course of nerve. Nonspeech Oral Mech: unilateral mandibular branch lesions: jaw deviates to weak side when opened, easily pushed to weak side by examiner. Degree of masseter and temporalis contraction is reduced. Bilateral weakness: jaw may hang open at rest, pt may be unable to close jaw or move it with reduced range, may resist E’s attempt to open or close jaw. Pt complaints include chewing difficulty, drooling, recognizing the jaw is difficult to close or move. If sensory branches affected: pt complaints of decreased face, tongue, cheek, teeth or palate sensation. Speech: Apparent during reading, conversation, and AMRs. AMRs: imprecision or slowness for “Puh” are greater than that for “tuh” or “kuh”. Unilateral damage to V generally doesn’t perceptibly affect speech, while bilateral has devastating effects. Affects bilabials, labiodentals, lingual dentals, and alveo-dentals, among others. Speech rate slow Sensory lesions also can affect precise articulations Facial Nerve (VII) Lesions Can be damaged in isolation or along with other CNs. Infectious causes: herpes zoster, mono, OM, meningitis, lyme disease, syphilis, sarcoidosis, GBS, etc. Neoplastic: acoustic neuroma, parotid tumor, cerebellopontine angle meningioma, tumor of facial nerve, etc. Vascular lesions and trauma also Bell’s palsy relatively common, acute onset of isolated unilateral upper and lower facial nerve weakness. Nonspeech Oral Mech: at rest, affected side sags, is hypotonic. Forehead may be unwrinkled, eyebrow drooped, eye open and unblinking, drooling on affected side, nasolabial fold often flattened, during smiling the face retracts more toward the intact side. Food may squirrel between teeth and cheek on weak side because of buccinator weakness, pt may bite cheek or lip, difficulty keeping food in the mouth, reduced or absent movement is apparent during voluntary, emotional, and reflexive activities, fasciculations and atrophy may be apparent on the affected side. Bilateral lesions less common, effects of weakness less apparent because of symmetric appearance. At rest, mouth may be lax and more open than normal.. smiling, corners of mouth not as upturned. Patient may be unable to retract, purse or puff the lips, seal may be easy to break. Fasciculations may be evident in perioral area and in chin, pts are unaware of them. Pts may complain their lips do not move well during speech, or that they lose food or liquid out of their mouth. Drooling may be observed.  Abnormal movements: synkinesis is the abnormal contraction of muscle adjacent to muscle that is contracting normally. Hemifacial spasm: paroxysmal rapid and irregular (unilateral usually) tonic spasm of the facial muscles. Facial myokymia is characterized by rhythmic, undulating movements on an area of the face in which the surface of the skin moves like a bag of worms. Speech Conversational speech, reading, speech AMRs and stress testing. Flutter of the cheeks may be evident during conversation (hypotonicity results in less resistance to intraoral air pressure peaks during pressure sound production. In general, precision is reduced more than speed, unless weakness is BL and severe. Effects of UL facial nerve paralysis on speech can be more visible than audible. May be mild distortion of bilabial and labiodental consonants. BL facial weakness can lead to distortions or complete inability to produce p, b, w, m, hw, f, and v. Glossopharyngeal (IX) Lesions Rarely damaged in isolation (X is usually involved) Nonspeech Oral Mech: Gag reflex to test, particularly for asymmetry in the ease in which the reflex is elicited Glossopharyngeal neuralgia exists in some patients… severe pain beginning in throat and radiating down to neck to back of lower jaw triggered by swallow or tongue protrusion Speech Cannot be assessed directly (role of IX in speech) Probably influences resonance and perhaps phonatory functions. Vagus Nerve (X) Lesions Intramedullary lesions damage the nerve within the BS Extramedullary lesions damage the trunk of the nerve as it leaves the BS vut while it is still within the cranial cavity Extracranial lesions damage the nerve after it exits the skull. Generally the case that as the distance of a lesion from the BS increases, the number of muscles, structures, and functions affected by the lesion decreases. Thus, intracranial lesions are more likely than the others to be bilateral or associated with multiple CN involvements. Extramedullary lesions are more likely to be unilateral, but may still affect several CNS (e.g., IX, X, and XI). Lesions above the level of separation of branches affect everything below them, thus all branches on the side of the lesion are weakened or paralyzed. Lesions below pharyngeal branch but above superior and recurrent branches spare upper pharynx and VP mechanism but damage cricothyroid and other intrinsic muscles on side of lesion Lesions of SL branch but not RL or pharyngeal branches affect the cricothyroid but not the VP mechanism or remaining intrinsic muscles. Lesions affecting only RLN affect all intrinsic laryngeal muscles except CT. Nonspeech Oral Mech UL pharyngeal branch: soft palate hangs lower on side of lesion, pulls toward nonparalyzed side on phonation, gag reflex diminished on weak side BL pharyngeal branch: palate hangs low in pharynx at rest, moves minimally or not at all during phonation, gag reflex may be difficult to elicit or absent, nasal regurgitation may occur during swallow. Laryngeal appearance: can be shortening of affected TVF and shift of epiglottis and anterior larynx toward the intact side (UL lesions_, shortening and bowing of the affected VF, epiglottis overhang with obscuring of anterior portion of the vocal fold or folds, paramedian position of paralyzed VF, and abducted position of the VF. UVFP: dysphagia may be present in more than half of pts, cough and glottal coup may be weak, may be airway compromise. BL paralysis, airway comp and inhalatory stridor often occur, dysphagia and other signs of weakness are worse. Speech if weakness is BL, hypernasality can be marked to severe, audible nasal emissions, pressure consonans imprecise, loudness reduced, phrase length reduced, facial grimacing, etc. UL lesions below pharyngeal branch but including SLN and RLN may result in breathiness, aphonia, hoarseness, reduced loudness, diplophonia, reduced pitch, pitch breaks. Lesions of SLN (UL) cause mild breathiness or hoarseness, mildly reduced ability to alter pitch, loudness normal or mildly reduced. BL means more severe of these symptoms. UL RLN lesions can cause breathy-hoarse voice quality, decreased loudness, sometimes diplophonia and pitch breaks. BL, voice may be unaffected but inhalatory stridor present.. Accessory Nerve (XI) Lesions Similar etiologies to that of CN X. Spinal portion can be damaged by lesions in cerv ical spinal cord and by compression from lesions in the area of foramen magnum, radical neck surgery is another source. Nonspeech Oral Mech Reduce shoulder elevation on side of lesion Weaken head turning to side opposite of lesion Usually do not affect speech If significant BL weakness is present, respiration, phonation, and resonance my be indirectly and mildly affected by postural distortion Hypoglossal Nerve (XII) Lesions Innervates all intrinsic and extrinsic muscles of tongue except for palatoglossus… crucial for lingual articulatory movements as well as chewing and swallowing Lesions can be intramedullary, extramedullary, and extracranial. Most common cases of isolated XII lesions include postoperative complications, neoplasms, inflammatory conditions, postradiation effects, nonsurgical trauma, stroke, other vascular conditions. Nonspeech Oral Mech UL lesions tongue may be atrophic and shrunken on weak side, tongue deviates to the weak side on protrusion, ability to curl the tip of tongue to weak side in mouth diminishes, as is ability to push tongue into the cheek against resistance. Voluntary tongue lateralization within mouth can yield paradoxical results. BL lesions, tongue may be atrophic bilaterally, with bilateral fasciculations. May protrude symmetrically, but with limited range or not at all. Lateralization and elevation may be impossible. Saliva may accumulate and food may squirrel in the cheeks, patients may be unable to move food around in their mouths, may complain that their tongue feels “heavy”, “thick”, or “big” or that it does not move well for eating or speaking. Speech imprecise articulation of lingual phonemes BL lingual weakness affects sounds requiring elevation of tip or back of tongue When weakness is mild anterior distortions are detected more readily because of greater number of occurrence, but when weakness is more pronounced, velars can be particularly affected. Resonance affected occassionally by BL weakness Mose useful tasks for assessing lingual movement for speech are connected speech (stress testing if MG is suspected), speech AMRs Spinal Nerve Lesions upper cervical spinal nerves supplying neck are indirectly involved in voice, resonance, and articulation. Phrenic nerves each innervate half of the diaphragm Diffuse impairment of spinal nerves supplying respiratory muscles is often necessary to interfere significantly with respiration, unless the damage is to the 3-5 segments of the cervical spinal cord which can paralyze the diaphragm bilaterally Nonspeech Oral and Respiratory Mechanisms Rapid, shallow breathing Flaring of nasal alae Use of upper chest and shoulder neck muscles to help inhalation Lack of ability to hold breath Speech FD resulting from isolated respiratory disturbance is uncommon Respiratory weakness reduces the the amount and force of expelled air, reduced vital capacity and control of expiration can result in short phrases and reduced loudness. Prosodic abnormalities may result, as well as decreased pitch and loudness variability. Individuals may attempt to speak on residual air, causing a strained voice. Respiratory weakness in combination with CN weakness in FD is not unusual, distinguishing between phonatory and prosodic abnormalities resulting from respiratory versus laryngeal weakness can be difficult. Gasping, shoulder elevation, nasal flare, neck retract > common in respiratory weakness Pts with laryngeal adductor weakness complain of SOB during speech, but those with respiratory weakness complain during speech and other times as well. Pts with isolated respiratory weakness may have reduced loudness and breathy or strained voice quality, but not hoarseness, harshness or diplophonia which are > common in laryngeal weakness. Glottal coup differences Multiple Cranial Nerve Lesions When several CNs are affected, condition often referred to as bulbar palsy Jaw, face, lips, tongue, palate, pharynx, and larynx can be affected in varying combinations and to varying degrees depending on damage extent. Multiple rather than single cranial nerve involvement is more common in certain diseases such as MG, ALS, and BS vascular disturbances or tumors Speech  Similar to those associated with isolated CN damage, but effects are in combination are typically more severe than in single CN damage situations, but not always the case. Distribution of Speech Cranial Nerve Involvement Cranial nerve V and respiratory contributions to FDs were infrequent CNs VII and XII were involved much more frequently and CN X more often than any other speech CN. Pharyngeal branch was infrequently implicated, whereas laryngeal branches were frequently implicated More than 40% of the sample had unilateral or bilateral involvement of a single cranial nerve (most often X) and the majority of the sample had unilateral or bilateral involvement of more than one CN. Clusters of Deviant Speech Dimensions DAB found 3 clusters associated with flaccid dysarthrias: 1. Phonatory incompetence: breathy voice, audible inspiration, short phrases. Represents laryngeal valve incompetence. 2. Resonatory incompetence: includes hypernasality, nasal emission, imprecise consonants, and short phrases. Represents weakness of the velopharyngeal valve 3. Phonatory-prosodic insufficiency: consisted of harsh voice, monopitch, and monoloudness. Likely reflects hypotonia and weakness in laryngeal muscles. The first two clusters are especially important for differential Dx because they were not found in other dysarthria types. Thus, the presence of phonatory or resonatory incompetence is suggestive of flaccid dysarthria and implicates LMN weakness at the laryngeal and velopharyngeal valves (X). 3rd cluster does present in other dysarthria types. SUMMARY OF CHAPTER 4 1. Flaccid dysarthrias reflect damage to the motor units of cranial or spinal nerves that serve speech muscles. They occur at a frequency comparable to that of other single dysarthria types. They sometimes reflect weakness in only a small number of muscles and can be isolated to lesions of single cranial or spinal nerves. Weakness and hypotonia are the underlying neuromuscular deficits that explain most of the abnormal speech characteristics associated with flaccid dysarthrias. 2. Lesions anywhere in the motor unit can cause flaccid dysarthrias, and various etiologies can produce such lesions. Degenerative disease and surgical trauma are common known causes, but the etiology is sometimes uncertain, particularly when only a single cranial nerve is involved. Stroke, myasthenia gravis, tumor, infection, demyelinating diseases, anatomic malformations, and radiation therapy effects represent some other known causes. 3. Speech characteristics and nonspeech examination findings differ among lesions of cranial nerves V, VII, X, and XII and spinal respiratory nerves. Examination can localize the effects of disease to one or a combination of these nerves. 4. Lesions of the mandibular branch of the trigeminal nerve (V) lead to weakness of jaw muscles. When bilateral, jaw weakness can have significant effects on articulation. Lesions of the trigeminal nerve that affect sensation from the jaw, face, lips, tongue, and stationary points of articulatory contact may also affect speech, primarily articulatory precision. 5. Lesions of the facial nerve (VII) can cause facial weakness and flaccid dysarthria. Unilateral weakness of the face can be associated with mild articulatory distortions. Bilateral lesions may lead to significant distortion of all consonants and vowels requiring facial movement. 6. Lesions of the vagus nerve (X) cause some of the most frequently encountered manifestations of flaccid dysarthrias. Lesions affecting the pharyngeal branch can lead to hypernasality, nasal emission, and weak pressure consonants. Lesions of the superior laryngeal and recurrent laryngeal branches can lead to various voice abnormalities in which perceptual attributes are consistent with weakness and hypotonia of laryngeal muscles. Lesions above the pharyngeal branch can lead to both resonatory and laryngeal incompetence, whereas lesions below the pharyngeal branch are associated with laryngeal manifestations only. 7. Lesions of the hypoglossal nerve (XII) can cause tongue weakness. The resulting flaccid dysarthria is reflected in imprecise lingual articulation, with severity dependent on the degree of weakness and whether the lesion is unilateral or bilateral. 8. Lesions affecting spinal respiratory nerves can reduce respiratory support for speech and lead to reduced loudness and pitch variability, as well as reduced phrase length per breath group. 9. Phonatory and resonatory incompetence are commonly encountered distinguishing features of flaccid dysarthrias. Although they are tied to involvement of cranial nerve X, it is nonetheless important to attend to speech movements generated through cranial nerves V, VII, and XII. This is important both for a complete description of the speech disorder and because speech deficits isolated to single cranial or spinal nerves are possible in flaccid dysarthrias and unusual in other dysarthria types. 10. Flaccid dysarthrias can be the only, the first, or among the first and most prominent manifestations of neurologic disease. Their recognition and localization to cranial and spinal nerves subserving speech can aid the localization and diagnosis of neurologic disease. Their diagnosis and description are important to decision making for medical and behavioral management.