لکنت زبان نوروژنیک در استحاله گانگلیونی: گزارش یک مورد

Corticobasal ganglionic degeneration (CBGD) is a progressive neurological disorder characterized by gradual nerve cell loss and atrophy of the cerebral cortex and basal ganglia. Symptoms of the disorder include verbal apraxia and language disturbances along with bradykinesia and rigidity. There have been no reports to date of acquired or neurogenic stuttering associated with CBGD. We describe a patient whose initial symptom of CBGD was stuttering which worsened as her disease progressed. Neuroimaging including PET scans revealed poor metabolic functioning of the right basal ganglia. This finding, along with bilateral atrophy of the frontal and parietal lobes likely contributed to the disturbance of motor sequencing skills and led to the development and worsening of stuttering, apraxia of speech and swallowing, and eventual aphasia and cognitive decline. We suggest that neurogenic stuttering may be an additional symptom of CBGD.

Corticobasal ganglionic degeneration (CBGD) is a progressive neurological disorder characterized by gradual nerve cell loss and atrophy of the cerebral cortex and basal ganglia. Symptoms include the progression of tremor, verbal and limb apraxia, bradykinesia and rigidity (Riley et al., 1990). Progression of symptoms in an asymmetric manner is a key feature of the disorder (Jankovic, 2007). The term corticobasal degeneration (CBD) is also used to describe the disease (Litvan et al., 1997). It has been suggested in the literature that CBGD is an under diagnosed disease particularly due to its similarity to Parkinson Disease (PD) and progressive supranuclear palsy (PSP) (Litvan et al., 1997). The best predictors of diagnosis of CBGD include asymmetric akinetic-rigid syndrome with late onset of gait and balance disturbances, limb dystonia, myoclonus and ideomotor apraxia (Litvan et al., 1997). Other symptoms include verbal apraxia, dysphasia, dementia, dysarthria and cortical sensory disturbances (Riley et al., 1990). In a recent study by Frattali, Grafman, Patronas, Makhlouf, and Litvan (2000) the language disturbances of 15 patients with CBD were described. The authors reported that 53% of their patients demonstrated aphasia syndromes including Broca's aphasia, anomic aphasia, and transcortical motor aphasia. Their patients demonstrated left frontal, parietal or temporal lobe atrophy on brain MRI studies. In this paper we describe the progression of speech deterioration in a patient with a medical diagnosis of CBGD whose initial and continual complaint was stuttering. As her illness progressed, her stuttering worsened, leading to the impression that neurogenic stuttering may be an additional symptom of CBGD. 2. Case Report Our patient, a 68-year-old right handed female, was initially seen by her neurologist due to concerns of stuttering and word finding problems. She was a fluent speaker throughout her childhood and adulthood without a history of developmental stuttering. She was extensively involved in volunteerism and gave frequent speeches and presentations. She described symptoms of stuttering and not being able to “get the word out” over the course of 1 year prior to her neurological examination. She described the problem as worse when she was anxious. She was becoming embarrassed by her non-fluent speech and began avoiding social speaking situations. She had a longstanding history of Bell's Palsy with a residual right facial droop and ptosis. She reported new numbness in the center of her upper lip. She had a history of bilateral hand tremor since childhood. There was a significant family history of tremor. There was no reported history of stuttering in her family but the patient reported that as her mother aged she developed speech problems, the specifics of which were not identified by the patient. There were no complaints of blurred or double vision, vertigo or dizziness. Gait was normal. The patient's initial evaluation by the speech–language pathologist revealed stuttering-like behavior in the form of difficulty initiating speech and sound repetition particularly on the initial sound of words during conversation. She also demonstrated inconsistent sound substitutions, additions and repetitions when reciting phonemically easy to complex words and phrases from the verbal agility subsection of the Boston Diagnostic Aphasia Examination (BDAE) (Goodglass & Kaplan, 1983a). The patient achieved a score of 8/14 on the verbal agility subtest of the BDAE due to sound repetition of the first or second syllable of words. A poor oral agility score on the BDAE (6/12) occurred due to slow and uncoordinated rate of isolated and alternating tongue and lip movement during the 5 s allotted time period for the response. Unsteady, variable pitch during sustained phonation was subjectively noted. There were no signs of vocal tremor or a strained/strangled or harsh voice during sustained phonation or during conversation. Tongue tremor upon protrusion of the tongue occurred. The patient's score on the auditory comprehension subtest of the BDAE was 100% accurate for complex ideational material and lengthy paragraph stimuli. Reading comprehension of increasingly lengthy and complex paragraphs from the BDAE was 100% accurate but the patient had to re-read the last and lengthiest paragraph three times prior to responding. She reported that recently, in order to fully understand what she had read, she had to re-read articles in the newspaper. The Boston Naming Test (BNT) was also administered to our patient during her initial speech pathology evaluation (Goodglass & Kaplan, 1983b). The patient exhibited one semantic paraphasia and required phonemic cueing to arrive at an accurate response on two other occasions. The patient commented that the required cueing and her semantic error were unusual for her given her pre-existing high level of language functioning. Normative data for the BNT is not available for the age of our patient. However, our patient's overall score was 57/60 on the BNT. The initial working speech diagnosis was most consistent with stuttering-like behavior in the form of difficulty initiating speech and sound repetition particularly on the initial sound of words. Oral and verbal apraxia was also noted based on conversation and the verbal agility subtest of the BDAE. The possibility of a progressive illness affecting speech and language skills was raised due to the recent history of speech changes and the subtle changes in reading comprehension. During the initial speech and language evaluation it was noted that our patient was stimulable for more fluent speech by slightly slowing her rate of speaking. She was therefore enrolled in two sessions of speech intervention. The focus of treatment was to practice a slower rate of speech as a compensatory strategy to improve fluency. This was successful for short phrase production. When the patient spoke of stressful familial situations, or was involved in lengthy conversations, an increase in sound repetition occurred. It was recommended that the patient practice the speech strategy at home and return for intermittent medical and speech monitoring over the next few months. Our patient was not seen again until she returned to our clinic 1 year later with markedly worsened speech production characterized primarily by the predominant feature of frequent sound repetition in conversation that severely interfered with her intelligibility of speech. Rate of conversational speech production was slowed by sound repetitions as judged informally in conversation. Repetitions were severe and most common on initial sounds, for example, “bl bl bl blood pressure” or “slo slo slo slowly” but sometimes reiterations occurred during short word production such as “tip tip top” for “tip top.” Retesting of the verbal agility subsection of the BDAE was unsuccessful due to the patient's marked difficulty initiating speech and numerous sound repetitions at the initiation of words. Sound repetitions occurred during counting and rote tasks as well as conversation. The patient closed her eyes and intentionally tried to slow her rate of speech in order to improve fluency. She reported that she tried to visualize the words before saying them but this was only successful during one trial of counting, and repetitions, although fewer, still occurred. Conversation revealed an abundance of single sound and syllable repetition to the point of near unintelligibility. This was the primary aberration of her speech. However, other speech abnormalities were present such as difficulty initiating speech with oral posturing noted and then once she began speaking she spoke rapidly with slightly distorted articulation and had difficulty slowing down until she was out of breath. This feature appeared consistent with palilalia (Duffy, 1995: chap 13; Helm-Estabrooks, 1999). Distorted articulation, low vocal volume, short phrase production, short rushes of speech, and monopitch were also present and most consistent with hypokinetic dysarthria. Facial expression however was normal, without signs of a masked face. There was an absence of secondary behaviors during sound repetitions. The patient remained well aware of her dysfluency. Compensatory strategies were not effective as the patient's fluency worsened. She demonstrated continued difficulty initiating speech with worsening repetition of sounds and words. Struggle and trial and error behavior of sound production appeared to worsen as well and was consistent with apraxia of speech. Cognitive changes progressed to the point where she was not safe in her home unattended. She was found to walk away from running water at the sink or forget where she was going once in her car. She reported the need for increased concentration and focus during reading and other tasks. A change in fine motor skills was reported and included a decline in writing and dressing. Her neurologist reported that she was exhibiting signs of limb and dressing apraxia. The patient began to complain of difficulty swallowing. A videofluorographic swallowing study revealed uncoordinated tongue and mouth movements to prepare a bolus for swallowing. Once the swallow response was triggered, the pharyngeal phase of swallowing was normal. These findings were consistent with an oral phase apraxia of swallowing, the only portion of the swallow process dependent upon voluntary motor sequencing. MRI of the brain at 1.5 T demonstrated cerebral atrophy with greater atrophy involving the right hemisphere than the left (Fig. 1a). The basal ganglia were morphologically normal. PET/CT was performed 2 months later. CT confirmed the preferential right hemisphere atrophy and the normal morphologic appearance of the basal ganglia (Fig. 2a, b). PET (18F-fluorodeoxyglucose) demonstrated decreased metabolic activity in the right thalamus, right basal ganglia, right frontal, right temporal, and right parietal lobes (Fig. 2c).

We propose that while apraxia of speech is a known symptom of CBGD, neurogenic stuttering may be an additional symptom of the disorder. Our patient's sound repetitions worsened as her disease progressed and her medical diagnosis of CBGD was confirmed 1 year after her initial speech and neurological evaluations. This patient demonstrated bilateral, asymmetric cerebral atrophy, metabolic dysfunction of the basal ganglia, thalamus, frontal and temporal lobes which likely contributed to her motor sequencing deficits resulting in neurogenic stuttering and apraxia of speech and swallowing as well as her eventual language and cognitive decline. This case highlights the importance of periodic monitoring of speech and language function in individuals with progressive neurological illness.