gms | German Medical Science

Communication disorders in neurological diseases are well-known and frequently described by neurologists and phoniatricians. They manifest mostly as speech disorders - aphasia and dysarthria. Voice disorders are too seldom diagnosed although they are often the first symptom of neurological diseases.

Motor Neuron Diseases - MND is a term that concerns the whole group of disorders of unknown etiology leading to the progressive degeneration of motor cells of the cerebral cortex - most of all of precentral gyrus, pyramidal tracts, motor nuclei of the cranial nerves and of the anterior horns of the spinal cord. Degeneration process may concern superior as well as inferior motor neuron. However unlike sclerosis multiplex and polineuropathies it doesn't lead to dysesthesia. It doesn't also affect motor nuclei of oculomotor nerves as in myasthenia gravis.

In 1896 Jean Martin Charcot described amyotrophic sclerosis with superior and inferior motor neuron impairment defined in french literature as Charcot Disease, in anglo-saxon - as Motor Neuron Disease (MND) and in the USA as Lou Gehring Diseae. Amyotrophic Lateral Sclerosis - ALS includes approximately 50% of MND cases. The term ALS regards also other conditions: actual amyotrophic lateral sclerosis, progressive bulbar paresis, spinal-muscular-atrophy-like syndrome, primary lateral sclerosis. MND comprises also rare conditions as e.g. Kennedy's syndrome. Current views of etiopathogenesis of the disease suggest viral infection, autoimmunological reaction neurotrophic factors deficiency, glutamate metabolism disturbances. Exposition to one or more of these factors can affect superior and inferior motor neuron cells in individuals with a certain genetic predispositions.

Two patients with speech and voice disorders as the first symptoms of MND (as it was diagnosed in the course of management) were referred to the Department of Phoniatrics and Audiology, 62-year-old male J.S. and 78-year-old female H.M. were hospitalized because of gradually progressive hoarseness, voice fatigueability and effort dyspnoea. The female presented also dysphagia, phono-articulato-respiratory dyscoordination and emotional lability. In both cases there was a several-month-history of the complaints. Both patients were hospitalized in neurological departments, where the male was diagnosed as MND with multilevel impairment of the motor neuron of the anterior horns of the spinal cord and the female as pseudobulbar paresis. Both patients underwent complete phoniatric evaluation including acoustic voice analysis as well as neurological assessment.

Neurological examination in both cases showed exacerbation of deep reflexes, fasciculations of the tongue muscles, muscles of the shoulder girdle, thighs and calves with associated muscular atrophy of thenar and hypothenar. Essential pathologies of the ENT examination were also found in both cases. They comprised pharyngeal areflexia, restricted tongue motor activity with fasciculations. Additionally the female presented with dissocation paresis of the soft palate (lack of movement during phonation associated with preserved swallowing) as well as retention of saliva in both piriform recesses.

In the perceptual voice evaluation of the male patient his voice was described as soft, temporarily hoarse, with tremors, produced with hypertension of the neck muscles, insufficient activation resonators, with maximum phonation time of 20s and voice range 150-250Hz. Articulation hypothymia was also observed.

The female voice was mat, too soft, tremorlike, with articulation hypothymia, maximum phonation time of 4s, voice range 210-320Hz; sluggish and blurred speech, without rythm or melody, with repetition of end-syllabes and uncoordinated articulation movements. Articulation of many speech sounds was blurred. Hypernasalization was also found.

In videolaryngoscopy in both cases vocal cords were sligtly reddish, but smooth with sulcus vocalis along their free edges. In the female patient there was sulcus vocalis only of the right vocal cord. In both cases vocal cords abducted only to the intermedial position. Incomplete glottic closure in the intermembranous part of the glottis or hour-glass shaped were found. Vibrations of the vocal cords were assymetrical, irregular, the amplitude of the vibration was greater than normal, with no mucosal wave and incomplete glottic closure. Increased voice intensity was associated with sphincterous contractions of the ventricular folds.

In the acoustic voice analysis MDVP similar pathologies were found in both cases - there were significant disturbances of all parameters describing frequency perturbance measures, most of all jitter. Parametres defining amplitude perturbations were only slightly changed (shimmer, vAm). Acoustic indicators of instability, fluctuations and tremors of the voice were also abnormal - there were significant pathologies in VTI parametres (Voice Turbulance Index), FTRI, ATRI, F₀ and Amplitude Tremor Intensity Index) and DSH (Degree of Subharmonics).

Results of the acoustic voice analysis in both cases prove perceptual findings of the voice changes (tremor, instability of pitch, temporary aphonia) and vocal cords atrophia observed in videostroboscopy.

Bak et al. [Ref. 1] described 6 cases of MND, in which communication disorders were the first and main symptoms of the disease, Carrow et al. [Ref. 2] analysed 79 MND cases and found dysphonia in 80% of them, hypernasalisation of the speech in 75%, voice tremor in 63%, raised medium voice range in 38% and lowered range in 8%. According to Langmore et al. [Ref. 3] dysarthria affects subjects with bulbar MND more often than than corticobulbar or spinal MND. In the cases of dysarthria with strongly marked hypernasalisation as a result of palato-pharyngeal insufficiency they suggest application of palate-elevating prostheses, which significantly improve speech intelligibility.

Silbergleit et al. [Ref. 4] assessed acoustic parametres of voice in ALS subjects who demonstrated perceptually normal voice quality. The results revealed statistically significant alterations related to frequency range and phonation stability. Abnormalities in voice analysis MDVP found in our patients reveal significant predominance of functional disturbances [Ref. 5].

Roth et al [Ref. 6] found out that the first symptom of MND may be spasmodic dysphonia. The presented case underscores the need to delay botulinum toxin treatment in any patient with recent onset symptoms, and to obtain thorough motor speech and voice, otolaryngologic and neurologic evaluation in all patients prior to consideration for injection of it.

Ball et al [Ref. 7] suggest introduction of a special protocol for measuring the early predictors of bulbar speech dysfunction, which include altered voice quality, speaking rate and communication effectiveness in MND subjects. It might be of assistance in establishing the diagnosis and monitoring early progression of the disease.

Sulcus vocalis of different degree was found in both described cases. It should be assumed that it is the laryngeal symptom of MND due to the atrophy of the vocal muscle.

Rosenbek and La Point [Ref. 8] suggest that voice and speech improvement in neurological disorders depends on the extent of functional normalization of the nervous system activity. Therefore the rehabilitation possibilities should be presented to the patients in a realistic way, so that it won't reduce their motivation to cooperate with precocious optimism.

Abnormalities in acoustic voice analysis MDVP in MND subjects reveal a significant predominance of functional voice alterations. Voice and speech disorders may be a predominant manifestation in early stages of MND. Sulcus vocalis due to the atrophy of the vocal muscle can be the laryngeal symptom of MND.