Cerebellar Syndromes : A Medical Student Guide

The cerebellum is central to normal motor function and co-ordination, and can be frequently affected in a number of common disease processes. However, medical student teaching relating to cerebellar anatomy and pathology is lacking, leaving many graduates with a significant knowledge gap. Junior doctors need to be able to recognize ‘cerebellar syndromes’ on presentation to hospitals, and to identify and manage reversible causes rapidly and effectively. After review of relevant literature, a simple approach to the functional anatomy and practical classifications of common cerebellar pathology is presented here, with a focus on symptoms, signs and examination techniques essential to medical school final exams.


Introduction.
The cerebellum (Latin for 'little brain') is located infero-posteriorly to the cerebral cortex, and is fundamental to normal neurological functioning, yet it was not until the early 20th Century that Flourens discovered its primary function to be in motor control and co-ordination. 1 The cerebellum may be affected in common neurological disorders such as stroke, multiple sclerosis and mass lesions, often producing a 'cerebellar syndrome'.Junior doctors need to be confident in recognition and investigation of patients presenting with cerebellar symptoms and signs appropriately in order to identify treatable causes and provide accurate prognosis.Textbook coverage of this area is notoriously disjointed, often leaving medical students with a significant knowledge gap.This article aims to provide a brief overview of the etiology of cerebellar disorders and a simple approach to history, examination and investigation of patients presenting with cerebellar syndromes.

Methodology.
A review of literature was performed using PubMed, Google Scholar, Embase and Medline databases for articles from 1975 to 2012 using the search terms: Cerebellum, Neurological Examination, Ataxia, and Cerebellar Syndromes.Additional papers were retrieved from reviews and references.Articles included were in the English language and related to anatomy and clinical examination technique of the cerebellar system.

Anatomy.
The cerebellum is attached to the dorsal aspect of the brainstem by three separate fibrous structures -the superior,

Abstract.
The cerebellum is central to normal motor function and co-ordination, and can be frequently affected in a number of common disease processes.However, medical student teaching relating to cerebellar anatomy and pathology is lacking, leaving many graduates with a significant knowledge gap.Junior doctors need to be able to recognize 'cerebellar syndromes' on presentation to hospitals, and to identify and manage reversible causes rapidly and effectively.After review of relevant literature, a simple approach to the functional anatomy and practical classifications of common cerebellar pathology is presented here, with a focus on symptoms, signs and examination techniques essential to medical school final exams.

Neocerebellum:
Coordination and planning of limb movement.

Reviews
A 'surgical sieve' approach to the commoner causes is illustrated in Table 1.

Symptoms and signs of cerebellar disease
The cerebellum operates at a subconscious level to control muscle tone, posture and co-ordination.Cerebellar disorders result in difficulties with the rate, rhythm and force of limb movements, gait and speech. 3The key symptoms and signs can be remembered using the mnemonic DANISH: • Dysdiadochokinesis -Inability to perform rapid alternating movements, especially of limbs.Patients may also present with symptoms relating to underlying pathology for example, headache, nausea and vomiting resulting from a cerebellar tumor; systemic upset associated with a cerebellar abscess, and pyramidal and sensory signs in multiple sclerosis.

A B
A guide to comprehensive examination of cerebellar function as may be expected in an undergraduate Objective Structured Clinical Examination (OSCE) is presented in Table 2.
Handy Hints: 1. Romberg's sign is often mistakenly attributed to cerebellar dysfunction.It is actually primarily a sign of pathology affecting the dorsal columns. 4The patient stands with their feet together and eyes closed; if they lose balance, the test is positive.Postural hypotension, anxiety and axial stiffness are potential causes of a false positive Romberg's.In cerebellar ataxia, the test is not positive: the patient cannot balance with open 2. Note that rapid repetitive movements can also be used to detect non-cerebellar problems; for example, in upper motor neuron lesions these movements are slow and deliberate, and in extrapyramidal conditions such as Parkinson's the movements start slowly, and may be small in amplitude and slow in speed.3.In disorders which predominantly affect midline cerebellar structures (tumors of the vermis/alcohol-induced damage), the finger-nose test, heel-shin test and testing for dysdiadochokinesis may be normal.It is therefore of important to check the stance and gait in cerebellar examination, as truncal ataxia may be the only abnormal finding.

"Overall, specific tests can be helpful in confirming or refuting the presence of cerebellar disease, but must be interpreted in the context of other signs and the case history." Investigation of Cerebellar Disease
Investigation should be guided according to the differential diagnoses in mind, but commonly includes blood tests and cerebellar imaging.

An approach to investigating cerebellar disorders:
• Toxic: Review drug charts, interactions, toxicology screen.Imaging: Computed tomography (CT) (Figure 2) or Magnetic resonance tomography (MRI) (Figure 3) of the brain are used to investigate cerebellar disorders and may reveal a stroke, space occupying lesion, demyelination or atrophy.

In Summary.
The cerebellum is affected by a number of common disease processes, producing characteristic symptoms and signs.
Junior doctors need to be able to accurately detect such 'cerebellar syndromes' since they are a common presentation to hospital and since there are a number of treatable causes which can be reversed if detected early. 5 A sound understanding of the anatomy of the cerebellum, etiology of cerebellar disorders and logical approach to examination will facilitate appropriate investigation and treatment.

Figure 2 .
Figure 2. CT head scan showing right sided cerebellar hemorrhage.This elderly patient presented with sudden onset headache, nausea, vomiting, unsteady gait and right sided clumsiness.

Table 1 .
'Surgical Sieve' approach to common causes of cerebellar syndromes.* Denotes common cause.