Dysmetria - Inability to arrest movement at desired point e.g., exaggerated splaying of fingers in grasping

olivo-pontocerebellar degeneration, olivo-rubro- cerebellar degeneration, delayed cerebellar degeneration 4 Neoplastic - CP angle tumour, pontine tumour, cerebellar tumour 5 Metabolic -Alcohol, myxoedema, inborn errors of metabolism, non-metastatic manifestation. of malignancy Clinical features of cerebellar lesion - A Localising value - I DISORDERS OF POSTURAL FIXATION - 1 Hypotonia 2 Rebound- an displacing the outstretched arm 3 Pendular knee jerk II DISORDERS OF MOVEMENTS -1 Intention tremor - Increased irregularity of movement as the finger approaches the nose in finger-nose test 2. Dysmetria - Inability to arrest movement at desired point e.g., exaggerated splaying of fingers in grasping a small object, or lifting the leg too high when attempting to place it on a chair with eyes shut 3 Dyssynergy - Defective co-ordnatlon of various muscles and muscle groups participating in a movement, e.g extending the trunk backwards without simultaneous flexion of the knees thus losing balance. 4. Dysdiadochokinesia - Disturbance of rapid alternatlng movements, e. g, rapid pronation and supination of forearm, or tapping the thigh alternately with the paJm and the back of the hand 5. Myoclonic jerks and choreiform Involuntary movements - with extensive cerebellar disease involving deep nuclei 6. Head tift - suggests lesion of inferior vermis. (Trochlear N. palsy and tonslllar hernlation can also produce such abnormal pasture) iii DISORDERS OF GAIT - 1. Broad based and reeling gait. 2 Deviation lo side of lesion.3 Trunca ataxia (unsteadiness when seated). B. Non-localizing - 1 Static tremors due to hypolonia. 2. Eye movements - (a) Nystagmus - In unilateral disease, amplitude and rate increase when looking towarok diseased side (b) Skew deviation. (c) Ocular dysmetria -An'overshoot' when the eyes voluntarily fixate. 3. Disturbance of speech - Scanning dysarthria with speech occasionafly delivered with sudden force - explosive staccato speech. 4. Vertigo - Objects move away from the side of lesion. Sense of rotation of the body in same drection with intra-cerebellar lesion. in opposite drection with extra-cerebellar leaion. 5. Titubation - Rhythmic nodding tremor of head from side to side or to and fro usually assocrated with distal limb tremor.6. Depressed jerks,7 Astereognosis. 8. Decerebraie rigidity.9. Cranial nerve involvement Investigations. First line 1. CT and MRI - will usually differentiate between cerebellar tumours, cerebellar stroke and other forme of cerebellar disease such as degeneration and demyelination.2. Thyroid function tests 3 LFTs - -gluTamyl transferase 4 Vitamin E 5. -fetoproten 6 Lipid profile 7. Investigations for malignancy (CXR, abdominal sono) 8. Visual evoked response Second line 1. CSF - to detect cerebellar inflammation 2 Antineuronal antibodies 3 EMG - for neuropathy 4 SCA mutations, mitichondrial gene analysis 5. DRPLA mutation - if family history 6. Fundat examination Differential Diagnosis 1. CEREBELLAR TUMOURS - Ataxia. symptoms of increased intracranial pressure (caused by hycfrocephalus due to obslruction of fourth ventricle) Astrocytomas and medullablastomas occur almost exclusively in children. 2. CEREBELLAR STROKE - (a) Infarction - Patients present with vertigo, headache, vomiting and ataxia. May have signs of brain stem involvement. Including ipsllateral Homers syntfome. contralateral hemisensory loss and cranial n involvement. (b) Hemorrhage -Symploms are difficult to differentiate from Infarction. Hypertension and anticoagulation re risk factors. 3. INFLAMMATORY DISEASES OF CEREBELLUM (a) Multiple sclerosis. (b) Brain abscess