Lecture 41 March 16th-nervous

1DDX: LECTURE 41 – MARCH 16th, 2007 CONDITIONS OF THE NERVOUS SYSTEM TEST #5 WILL START HERE (THIS IS NOT ON THE 21ST TEST) Page 1 Neurological history: Case history is vitally important. Use acronym “VINDICATE”: Vascular, Infectious, Neoplastic, Degenerative, Inflammatory/Immunologic, Congenital, Autoimmune, Toxic/Traumatic, Endocrine/Metabolic”. These are the options for your diagnosis. • Vascular: vasculitis, strokes, ischemia, compartment syndromes. • Infections: usually have cardial signs/symptoms (fever: although in very young/old, don’t have fevers. 90 years< and >3months • Neoplastic: with pressure atrophy signs/symptoms Need to know what is being affected in the nervous system (anatomy): didn’t cover this in detail. Pathways and tracts: Sensory: can be called different names. Crosses the midline “somewhere”: some cross right away, some ascend in the dorsal column. Crossing: provides redundancy so that if 1 nerve is damaged, another one is there to take over. Dormant cells are there as backup (strokes, accidents). The cells don’t recover, but others are recruited. Dorsal column: pain and crude touch Spinothalamic: from spine to thalamus. (Lateral: motor) 3 tracts: corticospinal: voluntary Corticobulbar tract and cerebellar tracts: there is a voluntary component, but not entirely. Lift a cup of coffee: we don’t think about how many fibres are recruited, we don’t account for gravity, weight of object, don’t have to think about steadying the movement, proprioception. Some of this movement is not voluntary, and these tracts take care of it. Cerebellar is feedback loop. Cranial nerves: more primitive, easier to identify. Dermatomes: can use these to diagnose brain damage. Neural exam: starts as soon as you meet the patient. DYSRAPHIC DISORDERS Anencephaly: 1-5 in 1000 End of neural tube doesn’t form. Meningocele: Cyst is lined with meninges, but does not contain neural tissue. Small surgery can deal with this, you are just removing a cyst. A bit less severe: will have spina bifida occulta. Mesenchyme usually wraps around neural tube and becomes bone. If it doesn’t fuse, it is “bifid”: has 2 ends instead of fusing. Covered with deep fascia and superficial fascia, and is often covered with a bit of hair. Least severe of conditions presented. Child will walk, survive. Meningomyelocele: Contains spinal cord. Can’t remove this once it forms… can’t push it back in, can’t cut it out. Nerves are irritated, will die, when they are pushed along a longitudinal plane. Have to relieve the pressure. Myelocele: most severe. No covering over spinal cord. CSF has leaked out. Not viable. May reach term but will not survive. Spina bifida aperta: is a smaller area than myelocele. Like spina bifida occulta without any covering. HYDROCEPHALUS Cycle of CSF: Made in ventricles of brain and circulates around brain and spine. Net flow that comes from the ventricles, and it has to leave in the same amount. Net gain will lead to hydrocephalus. Too much fluid and fontanelles haven’t closed? Head will enlarge. If this happens after fontanelles close, there is no room to grow. Pressure atrophy. Arnold Chiari Malformation: DDX LECTURE 41, MARCH 16th, 2007 – PAGE 1

Will cause downward displacement of the cerebellum. Will have severe co-ordination problems. If it continues, this is lethal. Life centres are in medulla (breathing, blood pressure). If medulla herniates through foramen, this is like hanging. Dandy-Walker Malformation Luschka and Magendie are foramena that connect through the cerebellum (?) Cerebellum is not there in the slide that we saw. Severe motor co-ordination problems, but compatible with life. Huge ventricles on CT scan. PHAKOMATOSES Tuberous Sclerosis Grey matter is cell bodies, white matter is myelinated axons. Distinction between grey and white matter is lost. Moles are hamartomas. If they are in non-vital place, no problem. In vital place, they cause epileptic seizure. May see facial nodules in these patients. Von hippel-Lindau disease The fact that there is a tumour suppressing gene suggests that neoplasms are a natural occurrence in the body. Hemangioblastoma: blood vessel, blastocyst. Grow in other organs too, esp. kidneys. Neurofibromatosis Two types: different gene. ACQUIRED DEVELOPMENTAL DISORDERS: Congenital Hydrocephalus: Illnesses caused by infections. Happens in early days of pregnancy.

DDX LECTURE 41, MARCH 16th, 2007 – PAGE 2