Flaccid Dysarthria falls within one of two major categories of motor speech disorders. Motor speech disorders are classified as either dysarthria’s or apraxia’s. Flaccid Dysarthria, which has to do with damage to the lower motor neurons, is only one of six categorized dysarthria’s, the others being as follows: Spastic Dysarthria, Ataxic Dysarthria, Hyperkinetic Dysarthria, Hypokinetic Dysarthria, and Mixed Dysarthria. Features of each of these dysarthria’s are distinctive due to the site of damage and can help with the diagnosis of the particular dysarthria.
The medical dictionary online defines flaccid dysarthria as weakness or paralysis of the articulatory muscles due to LMN disorders, causing hypernasality, imprecise consonants, breathy voice, raspy voice and monotony of pitch. In the most severe forms of flaccid dysarthria, it is characterized by the shriveling and flaccidity of the tongue and laxness & tremulousness of the lips. This is seen in advanced cases of lesions that are located in the motor nucleus of the lower pons or medulla oblongata.
As mentioned beforehand flaccid dysarthria occurs when there is damage to the lower motor neurons, specifically the region affected is the pons and the medulla located in the lower brainstem. An injury at this site is going to cause any number of the following characteristics to manifest: breathiness, hypernasality, short phrases, monopitch, imprecise consonants, diplophonia, poor intelligibility, impairment in elevating the tongue, drooling and or poor lip seal. Basically any of the subsystems of our speech system can be affected such as resonance, articulation, phonation, respiration and/or prosody. The damage that is caused to the lower motor neurons can be attributed to one of many causes such as, TBI (traumatic brain injury), tumors, aneurysms, viral infections, cerebrovascular accidents, or neuromuscular diseases such as, myasthenia gravis, Eaton-Lambert Syndrome, and/or muscular dystrophy.
The cranial nerves that are most associated and affected with lower motor neuron damage are the cranial nerves, V, VII, IX, X, XI, XII and/or the cervical thoracic spinal nerves innervating the diaphragm and other respiratory muscles. Since each of these cranial nerves controls different motor or sensory areas of the body, the characteristics and areas affected are distinct.
Damage to the Vth cranial nerve, the trigeminal nerve, will affect the sensory and/or motor aspects of the muscles of mastication, which are important for speech as well as for chewing and eating. A lesion in this area can also affect the jaw jerk reflex and cause poor lip seal, which could impede the lips or tongue from making the appropriately needed contact to form certain labial or lingua consonants and vowels. An SLP would most commonly work on resistive exercises such as opening...