THE NERVOUS SYSTEM Vitamin B1 (Aneurin or thiamine) deficiency
1. NUTRITIONAL POLYNEUROPATHY (Neuritic beriberi).
2. WEAN ICKE-KORSAKOFF SYNDROME- WernickeS encephalopathy -
Triad of: 1. Ophthalmoplegia - Eye signs consist of nystagrnus, Vlth and 111rd nerve palsies, gaze palsies and occasionally ptosis.
2. Ataxia. a Confusion - in early stages followed by disorientation, drowsiness and terminal coma. Neuropathological lesions - Petechial hemorrhages in grey matter around 3rd and 4th ventricles and aqeduct of Sylvius, including the mammillary bodies. Korsakoffs psychosis - is the permanent sequel to Wernickes encephalopathy and is characterised by severe, irreversible loss of short-term memory, with relative sparing of other aspects of cognitive function.
Some patients may confabulate. Neuropathological features are neuronal loss and gliosis, and hernosicierin-containing macrophages in the same distribution as lesions in Wernickes encephalopathy.
Nicotinic acid deficiency - Mental confusion, sometimes fits, peripheral neuritic or spinal cord lesions occasional.
Pyridoxine deficiency - 1. Chronic convulsions - in infancy may be due to lack of pyridoxine.
2. Polyneuropathy - as a complication of isoniazid treatment of tuberculosis arises from blocking of pyridoxine by the drug. Pantothenic acid deficiency - Burning feet syndrome - Intense discord oil in feet in absence of objective sensory alteration or of motor, or tendon reflex signs.
There are two lines of evidence for this - (i) Its reproduction in human volunteers by giving them omega-methyl-pantothenic acid, an analogue of the vitamin which ads as an antagonist. 00 Nitro' urazone, a drug used in treating trypanosomiasis, causes an acute burning feet syndrome which responds promptly to parenternal calcium pantothenate.
Vitamin B12 (Cyanocobalamin) deficiency — Types of disorders -
(a) Cerebral type - Symptoms cover a wide range and consist of mild disorders of mood, mental *slowness, memory defect which may be severe, confusion which may be persistent or relapsing delusions and paranoid behaviour and sometimes violent mania, visual and auditory hallucinations. Faecal and urinary incontinence in the absence of overt spinal lesions. Epilepsy and ctysphasia may occur. These cerebral symptoms depend on ciernyelinating lesion of the white matter in the brain of the same nature as occur in the posterolateral column of the spinal cord and peripheral nerves. Optic atrophy or its precursor retrobulbar neuritis is not uncommon and may be the first manifestation, occurring predominantly in males.
(b) Peripheral neuritis (See Polyneuritis).
(c) Subacute combined degeneration. ETIOLOGY -
(i) Age - 40-60. 00 Both sexes. Op Familial incidence known. (iv) Associated conditions - usually pernicious anaemia. Rarely as a result of carcinoma stomach, gastrectomy and gastro-enterostorny, steatorrhoea or malnutrition from protein deficiency. CLINICAL FEATURES - Onset - usually gradual, sometimes rapid.
1. Subjective sensory disturbances - Paraesthesia - Tingling and numbness in toes, later tips of fingers, rarely simultaneously in both upper and lower extremities. Sometimes burning or stabbing pains or even lightning pains like tabes. Paraesthesiae begin at periphery and tend to spread upwards.
2. Objective sensory loss - Sense of vibration, posture and passive movement vibration, first in lower, later in upper limbs. Glove and stocking type of superficial sensory loss. Tenderness of calf muscles. a Motor symptoms - weakness and ataxia develop at variable interval after onset of sensory disturbances.
4. Reflexes -and reduced reflexes. Death before 3 years of age.
(b) Type II SMA presents at about 6 months, and has, a more protracted course. Death from respiratory failure before age of 10.
(c) Type III SfsilA (Kugelberg-Welander disease) presents at about 10 years with life expectancy of about 35 years. Progression tends to be slower that lower motor neurone forms of MND. Differential Diagnosis of MND DISORDER/SYNDROME MAIN DIAGNOSTIC TEST Cerebral and brain stem disorders Infiltrating tumors Cranial MRI Vascular disorders Cranial MRI, CSF, (e.g. multifocal ESR infarction, vasculitis, C-reactive protein, AN malformations) autoantibodies Syringobulbia Cranial MRI Cranial neuropathies EMG, nerve neuropathy conduction studies Spinocerebellar Degenerations 1, FRIEDREICHS ATAXIA - Progressive familial disorder with atrophy of posterior columns, posterior root ganglia, pyramidal and spinocerebellar tracts. Presents in early teenage years with ataxia, peripheral sensory loss, areflexia, loss of postural tone, kyphoscoliosis, pes cavus and cardiac conduction defects. Mental changes develop in a few An underlying defect of membrane transport and lipoamicle dehydrogenase has been demonstrated.
2. FAMILIAL SPASTIC PARAPLEGIA Family history of pure motor paraparesis in siblings or parents. Usually patient presents in the first decade. Pes cavus is often present. a ABETALIPOPROTEINEMIA - If untreated may produce similar neurological picture.
4. Due To UNKNOWN BIOCHEMICAL ABNORMALITY - Hereditary spastic ataxia (Marie), hereditary areflexic dystasia (Roussy-Levy), and olivopontocerebellar atrophy. 21. CEREBELLUM AND ITS DISORDERS Anatomy - The cerebellum, situated in the posterior fossa beneath the tentorium, and attached to the brain stern by the superior, middle and inferior peduncles, comprises two lateral hemispheres and the vermis which contain afferent and efferent nerve fibres. AFFERENT CONNECTIONS: Functionally, the cerebellar cortex is divided into three parts:
1. Vestibulocerebellum (lower vermis), which receives afferents from the vestibular system.
2. Spinocerebellum (upper vermis and anterior parts of the hemisphere), which receives afferents from the spinal cord a Neocerebellum - (cerebellar hemispheres), which receive, afferents from the cerebral cortex. EFFERENT CONNECTIONS: Efferent fibres originate from the Purkinje cells and pass to either the vestibular nuclei or deep cerebellar nuclei, which gives rise to a variety of ascending and descending projections. Each cerebellar subdivision sends elf erents principally to that part of the nervous system from which it receives its afferents. Cerebellor cortex Afferent connections Dysfunction .Vestibulocerebellum Vestibular system Truncal ataxia (lower vermis) Spinocerebellum From spinal cord Unsteadiness of gait and stance (positive Rombergism) Neocerebellum intention tremor)
Causes: of cerebellar dysfunction - I. Acute - 1. Trauma - causing small capillary bleeding. 2. Infection - Encephalitis, abscess, Guillain Barre variant. a Vascular - Syndrome of posterior inferior cerebellar artery, anterior inferior cerebellar artery or superior cerebellar artery. Vertebro-basilar insufficiency. 4. Dernyelinating - Multiple sclerosis. 5. Drugs - Phenytoin, barbiturates, alcohol, streptomycin, gentarnycin, kenamycin, piperazine citrate. 6. Hyperpyrexia.l. Chronic - 1. Developmental - Agenesis, cranio-vertebral anomaly, Dandy Walker syndrome, von Hippel Linclau disease. 2. Familial - e.g., Refsurn's disease, lipidoses, leucodystrophies. a Degenerative - Holmes primary cerebellar degeneration,
