Cerebellar dysarthria

Published on 02/04/2015 by admin

Filed under Internal Medicine

Last modified 22/04/2025

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50 Cerebellar dysarthria

Instruction

Ask this patient a few questions.

Salient features

Examination

• The speech may be scanning (enunciation is difficult, words are produced slowly and in a measured fashion) or staccato (in bursts). Scanning speech is more common in multiple sclerosis, whereas staccato speech is more common in Friedreich’s ataxia.

• Articulation is uneven, words are slurred and variations in pitch and loudness occur.

• Proceed by telling the examiner that you would like to carry out a neurological examination of the patient for cerebellar signs.

See Case 46 (Cerebellar syndrome) for discussion.

Diagnosis

This patient has scanning speech (lesion) caused by cerebellar involvement secondary to chronic alcohol abuse (aetiology).

Questions

What do you understand by the term dysarthria?

Dysarthria is impaired articulation of speech. It may result from lesions of muscles, myoneural junctions or motor neurons of lips, tongue, palate and pharynx. Common causes include mechanical defects such as ill-fitting dentures or cleft palate. Dysarthria may also result from impaired hearing which begins in early childhood.

Advanced-level questions

How would you test the different structures responsible for articulation?

• Lips: ask the patient to say, ‘me, me, me’

• Tongue: ask the patient to say, ‘la, la, la’

• Pharynx: ask the patient to say, ‘kuh, gut’

• Palate, larynx and expiratory muscles: ask the patient to say, ‘ah’. In palatal paralysis the patient’s speech is worse when the head is bent forwards.

Articulation can also be tested by asking the patient to repeat the following:

• British constitution

• Hippopotamus

• Methodist episcopal

• Constantinople is the capital of Turkey.

What do you understand by ‘top of the basiliar’ syndrome?

Emboli to the rostral portion of the basilar artery usually produce this syndrome, with a myraid of possible symptoms characterized by visual, oculomotor and behavioural abnormalities, often without significant motor dysfunction. A top of the basilar syndrome is characterized by somnolence and sometimes, stupor; inability to make new memories; small, poorly reactive pupils; and defective vertical gaze. Patients with cerebellar infarcts often have dizziness, sometimes in conjunction with frank vertigo, blurred vision, difficulty walking and vomiting. These patients often veer to one side and cannot sit upright or maintain an erect posture without support. They may have hypotonia of the arm on the side of the infarct, a sign best elicited by having them hold their arms straight ahead and then rapidly lower them, quickly braking the movement. The hypotonic arm overshoots on both descent and rapid ascent. Nystagmus is common. Patients with pure cerebellar infarcts do not have hemiparesis or hemisensory loss.

What parts of the brain does the vertebrobasilar artery supply?

The vertebrobasilar arterial supplies the brainstem (medulla, pons and midbrain), cerebellum, occipital lobes, posterior temporal lobes and thalamus.

Remember: The vertebra-basiliar arterial system consists of the extracranial and intracranial vertebral arteries; these unite to form the basilar artery, which runs midline along the ventral surface of the brainstem, feeding it with small, deep perforators until it merges with the circle of Willis to give off the posterior cerebral arteries.

What is the significance of anti-Yo antibodies in a patient with cerebellar syndrome?

The presence of anti-Yo antibodies in the serum of a woman with cerebellar symptoms is virtually conclusive evidence that she has paraneoplastic cerebellar degeneration and gynaecologic, usually ovarian, cancer.

What is the role of chaperones in cerebellar tumours?

A chaperone complex (which typically maintains cellular protein assembly and function) mediates the assembly of the von Hippel–Lindau tumour suppressor protein; when this protein is not assembled correctly, its tumour-suppressing activity is lost, permitting the development and growth of tumours. A mutation in or deletion of part of this tumour-suppressor protein is associated with von Hippel–Lindau disease (characterized by phaeochromocytoma, renal carcinoma and densely vascularized retinal and cerebellar tumours).

What is the role of Sonic hedgehog Shh pathway in pathogenesis of medulloblastoma?

Medulloblastoma arises through abnormalities of developmental pathways in a population of progenitor cells. These tumours aberrantly express multiple regulatory genes known to mediate the proliferation of neural stem cells. Activity in the Shh pathway is important for the self-renewal of progenitor cells and the proliferation of their progeny, and also in the initiation of brain tumours. Medulloblastoma cells die rapidly when cultured with cyclopamine, an antagonist of the hedgehog family of regulatory pathways.

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