MSD ch 5 Spastic Dysarthrias PDF

SPD is a perceptually distinct MSD caused by BL damage to the direct and indirect activation pathways of the CNS. Can manifest in any or all of the respiratory, phonatory, resonatory, and articulatory components of speech, but it is rarely confined to a single component. Reflects combined effects...

SPD is a perceptually distinct MSD caused by BL damage to the direct and indirect activation pathways of the CNS. Can manifest in any or all of the respiratory, phonatory, resonatory, and articulatory components of speech, but it is rarely confined to a single component. Reflects combined effects of weakness and spasticity in a manner that slows movement and reduces its range and force. Spasticity, a hallmark of UMN disease, seems to be an important contributor to the features of the disorder. Encountered in medical practice at rate roughly comparable to that of the other major single dysarthria types, accounting for 5.7% of all the dysarthrias, and 5.4% of MSDs. Clinical features of SPD reflect the effects of excessive muscle tone (hypertonicity) and weakness on speech. There is a distinction between speech deficits attributable to weakness alone (flaccid dysarthria) and those in which the barriers to normal speech also include resistance to movement. Anatomy and Basic Functions of the Direct and Indirect Activation Pathways Direct activation pathways are also known as the pyramidal tracts or direct motor system, form part of the UMN system. The pathways include the CB tracts and the CS tracts. Their activities stimulate movements through the FCP (LMN). DAPs are bilateral, originating in each cerebral cortex, and leading directly to cranial and spinal nerve nuclei. Their fibers primarily innervate muscles on the side of the body opposite the cerebral cortex of origin. However, for the bulbar speech muscles, this applies only to the muscles of the lower face and to a lesser extent, the tongue. Remaining cranial nerves serving speech receive bilateral input from DAP and IDAPs.. this neural redundancy helps minimize the effects of unilateral UMN lesions. DAPs are primarily facilitatory, meaning impulses through them tend to lead to movement. IDAPs (extrapyramidals or indirect motor system) are also part of the UMN system. Originate in cortex of each cerebral hemisphere, but course indirectly because synapses occur between cortex and BS/SC, primarily in BG, cerebellum, reticular formation, vestibular nuclei, and red nucleus. IDAPs are crucial for regulating reflexes and maintaining posture, tone, and other activities that provide a framework for skilled movements. Many of their activities are inhibitory. Clinical Characteristics of UMN Lesions and Spastic Paralysis Damage to DAPs leads to impairment of fine, discrete movements. After acute lesions, reduced tone and weakness are evident, but generally evolve to increased tone and spasticity. Weakness is usually more pronounced in distal than proximal muscles, reflexes tend to be diminished initially but become more pronounced over time. Also associated with positive Babinski sign (abnormal), as well as pathologic oral reflexes in BL UMN disease (suck, snout, palmomental, jaw jerk) Damage to IDAPs affects their predominantly inhibitory role in motor control, lesions tend to lead to overactivity such as increased muscle tone, spasticity, and hyper-excitable reflexes. Spasticity is the result of hyperactivity of stretch reflexes, which goes hand in hand with increased muscle tone, results in resistance to movement. Patients with UMN lesions and hyperactive reflexes sometimes exhibit clonus, which is a kind of repetitive reflex contraction that occurs when a muscle is kept under tensions (stretch), the response may look like a rhythmic tremor. It is sometimes evident in the jaw, where it can have a shivering appearance. Damage to IDAP isolated or DAP isolated is rare because fibers from both are somewhat intermingled. As a result, people with spastic paralysis commonly have decreased skilled movement and weakness from DAP damage, as well as increased muscle tone and spasticity from IDAP damage. Major abnormalities that affect movement in spastic paralysis include spasticity, weakness, reduced ROM, and slowness of movement, these abnormalities are also the most salient features of disordered movement in pts with spastic dysarthria. The Relationship of Spastic Paralysis to SPD Neuropathophysiologic underpinnings of SPD are more complex and less understood than FD, because of: SPD is usually associated with damage to both DAP and IDAPs The degree to which concepts of spasticity can be applied validly to the CN innervated portion of the speech system is uncertain What we know about clinical manifestations of spasticity is mostly based on studies of limb movememtns that require the movement of joints in agonist and antagonist relationships with each other… but many speech movements do not have this (e.g., tongue being a muscular hydrostat). Additionally, speech structures have varying degrees of spindles (jaw is well populated, but face has none). Finally, unlike the limbs, the speech structures rely on symmetrically coordinated movements of bilaterally innervated structures Etiologies Any process that damages the direct and indirect activation pathways bilaterally can cause SPD. Exact causes of SPD is unknown, but degenerative and vascular disorders most likely are the predominant causes. Vascular disorders are more frequently associated with SPD than other dysarthria types. Vascular Disorders Strokes in internal carotid, MCA, and PCA, and less frequently in the ACA, can lead to SPD because these arteries mostly supply cortical & subcortical structures of the cerebral hemispheres, lesions in both L and R hemispheres are required to produce SPD. Whereas, in the brainstem, where right and left UMN pathways are in closer proximity, a single infarct may be sufficient to produce the BL damage necessary to create SPD, whereas a single cerebral hemisphere stroke does not. Brainstem strokes account for a substantial minority of all strokes, and 49-89% of such patients have dysarthria (spastic, flaccid and ataxic), but spastic type may be the most common. Some patients w/ SPD have had mutliple lacunes or lacunar infarcts (small deep strokes in small penetrating arteries of the BG, thalamus, BS, and deep cerebral white matter). Degenerative Diseases Primary lateral sclerosis (PLS), rare, motor neuron disease, beginning in 5th or 6th decade. manifests by corticospinal and corticobulbar tract signs with associated loss of neurons in the motor cortex but with no LMN involvement as in ALS. PLS can present as spastic dysarthria, Dx of PLS can be made with some confidence only if signs remain confined to UMNs for 3-4 years after symptom onset, because a substantial percentage of patients develop LMN findings before that time and then receive a Dx of UMN-dominant ALS. When SPD is the primary manifestation of a neurodegenerative disease, the disorder is sometimes referred to as progressive pseudo-bulbar palsy. (This is when the presenting and primary symptom is SPD but there is significant BL white matter loss in the motor cortex and descending motor pathways, and in some patients, hypo-metabolism in the premotor and motor cortices. Distinction between PLS and ALS is of interest because the median disease duration until death for PLS is about 10 years, much longer than for ALS. Congenital Disorders Cerebral palsy is very commonly associated with dysarthria, which can be severe. The dysarthria can be spastic in type, perhaps more frequently than other types. Inflammatory Disease Leukoencephalitis is an inflammatory demyelinating disease that affects the white matter of the brain or spinal cord. In acute hemorrhagic leukoencephalitis, white matter of both hemispheres is destroyed, with similar changes in the brainstem and cerebellar peduncles. These diseases can affect UMN pathways and cause spastic dysarthria or mixed dysarthrias. Speech Pathology Distribution of Etiologies, Lesions, and Severity in Clinical Practice Degenerative diseases account for a majority of cases (ALS, LPS, and PSP most common) Nonhemorrhagic strokes account for most of the vascular causes. Many vascular causes were > 1 stroke, singular strokes were usually in the BS. It is not uncommon for SPD to be accompanied by cognitive disturbances such as dementia or cognitive communication deficits associated with right hemisphere impairment, TBI, or aphasia; some patients have cognitive difficulties unrelated to the cause of their dysarthria. 13% had cog issues. Patient Perceptions and Complaints Frequently, speech is slow and effortful, sometimes feels as if they are speaking against resistance (not associated with other dysarthria types except for hyperkinetic). Often complain of fatigue with speaking, sometimes with accompanying deterioration of speech. With the exception of MG, complaints of fatigue occur more frequently in spastic rather than flaccid dysarthria, even though deterioration of speech in SPD is usually not dramatic and almost never rapid. Patients say they must speak slower to be understood, but admit that they can’t speak any faster. Finally, may complain of nasal speech but this is more common with FD. Swallow complaints common, including oral and pharyngeal phases of swallowing, when present the lesion is often in the BS. Drooling, more so than for other single dysarthria types Frequent gagging when brushing teeth Difficulty controlling expression of emotions… esp laughing and crying (pseudobulbar affect… more common than in other single dysarthria types). Clinical Findings Dysphagia very common and sometimes severe. (Study with 32 individuals, 94% had dysphagia and half of them couldn’t meet nutritional needs orally). At rest nasolabial folds may be smoothed or flattened or the face may be held in a somewhat fixed, subtle smiling or pouting posture. Reflexive or emotional facial movements frequently emerge slowly but may then overflow and be excessive Lability, affect, or pseudobulbar affect is common Normal jaw strength Jaw clonus sometimes evident when mouth opens for a jawn or when jaw is relaxed after the teeth are clenched Face may be weak BL, range of lip retraction and pursing may be decreased, but lower facial weakness is usually not as pronounced as with LMN lesions Tongue usually full and symmetric, but ROM may be reduced and weakness during strength testing Nonspeech AMRs for jaw, lip retraction and pursing, and lateral or anterior tongue movments are often slow and reduced in ROM. Palate usually symmetric but may move slowly or minimally on phonation Gag reflex often hyperactive Cough and glottal coup may be normally sharp if respiratory and laryngeal movements are not too slowed, but may lack sharpness if slowness is prominent. Pathologic oral reflexes common Speech Conversational speech and reading, speech AMRs, and vowel prolongation are the most useful tasks for eliciting the salient and distinguisshing characteristics of SPD. Speech stress testing and sequential motion rates are not particularly revealing Chief disturbances are slowness and reduced range of individual and repetitive movements, reduced force of movement, and excessive or biased muscle tone or spasticity. Bias of muscle tone most apparent at the laryngeal valve, in which it is towards hyperadduction during phonation Clusters of Deviant Dimensions and Prominent Deviant Speech Characteristics 1. Prosodic excess: represented by excess and equal stress and slow rate. Reflect slowness of individual and repetitive movements. 2. Articulatory-resonatory incompetence: represented by imprecise consonants, distorted vowels, and hypernasality. 3. Prosodic insufficiency: consisting of monopitch, monoloudness, reduced stress and short phrases. Reduced vocal variability, with stressed syllables left unstressed or insufficiently different from unstressed syllables, and reduced pitch and loudness variability (decreased ROM likely explanation). 4. Phonatory stenosis: characterized by low pitch, harshness, strain-strangled voice, pitch breaks, short phrases, and slow rate. Narrow glottis with a secondary reduction of phrase length and speech rate. Breathiness discovered in some pts with SPD, not correlated to any of the clusters. Acoustic and Physiologic Findings Respiration possible that people with acquired SPD have respiratory difficulties similar to those confirmed for children and adults with spastic CP. These abnormalities include reduced inhalatory and exhalatory respiratory support volumes, leading to shallow breathing, paradoxical breathing, in which abdominal muscles fail to relax during inhalation, leading to restricted respiratory intake, and reduced VC. Laryngeal Function At rest may be normal, but bilateral hyperadduction of the TVF and FVF during speech might be apparent EMG and aerodynamics have documented features of hyperfunction such as increased subglottal air pressure, increased glottal resistence, and decreased laryngeal airflow in dysarthric speakers with stroke…. However, some speakers have had hypofunctional activity Velopharyngeal Function Palate may move slugglishly or not at all during vowel prolongation (oral inspection) Palatal immobility, slow movement, and incomplete VP closure may be evident during videofluroscopy and nasoendoscopy Articulation, Rate, and Prosody Acoustic studies support inferences that movement rate is slow and movement range and precision are reduced. Within each speech subsystem there is evidence of slowness, reduced range and precision of movements, and sometimes variability of movement control. SUMMARY OF CHAPTER 5 1. SPD results from damage to the direct and indirect activation pathways (UMNs) bilaterally. It occurs at a frequency roughly comparable to that of other single dysarthria types. Its deviant speech characteristics reflect impaired movements and movement patterns, usually at all levels of speech production. The combined effects of weakness and spasticity on the speed, range, and force of movement seem to account for most of the abnormal speech characteristics of the disorder. 2. Clinical signs that accompany SPD usually include weakness, loss of skilled movement, spasticity, hyperactive reflexes, and pathologic reflexes. The salient effects of UMN lesions on speech movements include spasticity, weakness, reduced range of movement, and slowness of movement. 3. Degenerative and vascular etiologies probably account for a majority of cases, but congenital, traumaticd, demyelinating, and undetermined etiologies are not uncommon. Most patients have other clinical signs or neuroimaging evidence of bilateral UMN dysfunction, but in some cases the dysarthria is the only neurologic sign. The distribution of offending lesions can be widespread in the UMN system, including pathways anwhere from the cortex to the brainstem. 4. Dysphagia and pseudobulbar affect are common, as are complaints that speech is slow and effortful and deteriorates with fatigue. 5. The major clusters of deviant speech characteristics include prosodic excess, articulatory-resonatory incompetence, prosodic insufficiency, and phonatory stenosis. Although many deviant speech characteristics can be evident, strained-harsh voice quality, reduced pitch and loudness variability, slow speech rate, and slow and regular speech AMRs are the most distinctive clues to the presence of SPD. 6. In general, acoustic and physiologic studies of individuals with SPD have provided quantitative support for its clinical perceptual characteristics. They have helped specify more completely the speech subsystem location and the dynamics of abnormal movements that lead to the perceived speech abnormalities. 7. Spastic dysarthria can be the only, the first, or among the first or most prominent manifestations of neurologic disease. Its recognition can aid the localization and Dx of neurologic disease and may influence decision making for medical and behavioral management.