LMNL + Peripheral Nerve Disorders PDF

Lower motor neuron lesion & Disorders of the peripheral when I say something is important or comes in the exams im 100 right nerves neurology is a complex topic so it's much easier if we learn the foundation then slightly building up slowly Dr. Tariq Alfahad Amenan Aldezmi Assistant professor o...

Lower motor neuron lesion & Disorders of the peripheral when I say something is important or comes in the exams im 100 right nerves neurology is a complex topic so it's much easier if we learn the foundation then slightly building up slowly Dr. Tariq Alfahad Amenan Aldezmi Assistant professor of Neurology, Faculty of medicine, Kuwait University Consultant neurologist/neuroimmunologist, Ibn Sina hospital, Kuwait Introduction For a motor command to happen younever controlthemusclein particular youcontrolthe movement Upper motor neuron: starts from motor cortex à ends at LMN** ocated Lower motor neuron : starts from g Corticobulbar tract brainstem & anterior horn of spinal cord someEre à ends at muscle here Skeletal muscles Taste tEe Corticospinal tract Motor cranial nerve fibers contraction **UMN in brainstem control involuntary movements Motor spinal nerve fibers LMN Outline… Outline… Outline… Lower motor neuron lesion & disorders of the peripheral nerves What are the clinical features of LMNL? signs • Weakness • Due to decreased number of functional motor units • Muscle atrophy you only see skin bone • Due to disuse + lack of trophic factors from LMN In nourishing faro What are the clinical features of LMNL? • Hyporeflexia • Reflexes can be decreased or absent What are the clinical features of LMNL? • Hypotonia • Decreased muscle resistance to passive movement Foppyn imp in exams • Fasciculations like when a person is dead wean experienced it alittle likewhenthetwitches • Muscle fibers contraction seen as skin flickering but the contraction is not strongenough tomove a limb Important Upper motor neuron lesion vs Lower motor neuron lesion UMNL Anatomy LMNL Above anterior horn cell Ant horn cell + axon, in SC & above nuclei of cranial nerve nuclei + CN (CNS lesion) axon (CN) (PNS lesion) Examples Stroke, spinal cord injury Polyneuropathy, GBS, Remember early UMNL* thisone * Signs of UMN lesion takes hours to days to weeks to develop UMNL LMNL Tone* Increased (spasticity**) Decreased (flaccidity) Weakness UL: extensors > flexors Distal > proximal pattern LL: flexors > extensor hand shoulder Flexor = extensor *Tone: is muscle resistance to passive movement ** Spasticity: increase muscle tone that is velocity dependent when im moving the arm increase the speed of movementtonechanges A Deep Tendon UMNL LMNL increased decreased Usually absent Not affected Reflexes Superficial (abdominal reflexes) strokingabdomen muscle reflex Clonus exaggerationofdeep tendonreflex UMNL LMNL present absent snaking g UMNL in all exams Plantar 1 Extensor (positive Babinski response sign with dorsiflexion of big LMNL Flexor or absent toe & fanning of other toes) strike the lower foot when you ideally the toes would go down up w babinskisign theygo UMNL LMNL Positive (i.e thumb flexion) Negative alsoinexams p Hoffmann sign Hoffman when youpick the middle fingeryou get exion of thumb forefinger hey cometogether deallynothingwould happen w a trick UMNL LMNL Fasciculation absent Sometimes present Wasting Disuse atrophy (mild) Present (marked) mostimp in exams UMNL erthingisinor wer anatomy superficialreflexes onlytone t DTR will be absent in the beginningof then pickup later LMNL Above anterior horn cell Ant horn cell, motor in SC & above nuclei of CN nerve Examples Stroke, multiple sclerosis Polyneuropathy, GBS, early UMNL Tone Increased (spasticity) Decreased (flaccidity) Weakness pattern UL: extensors > flexors LL: flexors > extensor Distal > proximal Flexor = extensor DTR increased decreased Superficial Usually absent Not affected Clonus present absent Plantar response Extensor (upgoing toe; positive babinski) Flexor or absent Hoffman sign Positive Negative (abdominal reflexes) Mixed Fasciculation absent Sometimes present Wasting Present (marked) Disuse atrophy (mild) ALS Phases of spinal shock n orderforsignsof unn to ppeartheytake time o when i say Phase cutestroke in exam n't look for un nsbecausetheywon't pearimmediately 1 Time Clinical signs Underlying physiological event 0-1 days Areflexia Loss of descending facilitation 2 1-3 days Initial reflex return Denervation supersensitivity 3 1-4 weeks Hyperreflexia Axon-supported synapse growth 4 1-12 months Hyperreflexia, Spasticity Soma-supported synapse growth Diseases causing LMN lesion *mixed UMN & LMN Polio-myelitis Spinal muscular atrophy Amyotrophic lateral sclerosis (ALS)* Polio-myelitis Rare because of vaccine • Cause: • Polio virus à anterior horn cells destruction • Clinical picture: • 95% asymptomatic • 0.1% à LMN picture • Diagnosis: rt-PCR CSF • Treatment: supportive • Prevention: OPV/IPV all you need to know No sensory loss only motor Spinalmuscular muscularatrophy atrophy Spinal (SMA) • Cause: genetic (mostly autosomal recessive) • Clinical picture: progressive weakness & atrophy • Diagnosis: molecular genetic testing • Treatment: Antisense oligonucleotide (ASO) Amyotrophic lateral sclerosis (ALS)(ALS) Amyotrophic lateral sclerosis important • A degenerative motor neuron disease • Affects motor neurons in cerebral cortex, brain stem and anterior horn of spinal cord • combination of UMN and LMN signs • Course: progressive à fatal in 3-5 years • Treatment: supportive Lower motor neuron lesion & A disorders of the peripheral nerves Anatomy & Terminology Dorsalrootganglia Neuron-opathy Plexus Plexopathy Peripheralnerves Peripheral neuropathy anteriorhorn Motor neuron disease Root Radiculopathy Neuronopathy Detailsarenot necessary • Diseases affecting the neuron cell body • Divided into: • Motor neuron disease (anterior horn affected) • Sensory neuronopathy OR Ganglionopathy • Degeneration of dorsal root ganglia & projections sensory • Presentation: multifocal sensory symptoms • Examples: herpes zoster risk 50 on immunosuppressant Radiculopathy oneimportantpoint when someonecomplains ofneck pain ask doesitradiate if itmoves down the arm radiculopathy radiation Lowerbackpain radiatesdown theleg radiculopathy • Often involves one spinal nerve root • Presentation: • Weakness à in muscles supplied by that root (myotome) • Sensory symptoms à in root dermatome • Including radiating pain • Decrease DTR à in corresponding root ONLY • Causes: • Usually compression (by herniated disc) • Example: (next slide) Discbudging compressingnervero Radiculopathy Nodetailsneeded Howdo I localize a radiculopathy musclesinsamemyotome Plexopathy Detailsnot imp z • Can involve part or all of nerve plexus • Brachial plexopathy • Lumbosacral plexopathy • Presentation: • Weakness & numbness depends on parts of plexus affected • Causes: diabetes mellitus, focal mass (Pancoast tumor) Foseproximity to brachial plexus Peripheral neuropathy Detailsnot necessary just know it can behereditaryor acquired • Causes: • Hereditary • E.g Charcot Marie Tooth disease, others • Acquired classic exp • Metabolic/Medication (e.g diabetes mellitus, vitamin B12 deficiency, chemotherapy) • Immune (e.g vasculitis, GBS, SLE) • Neoplastic (paraneoplastic, paraproteinemic) • Infections (e.g HIV, Hepatitis B & C, Lyme disease) • Physical (compression, trauma) This is important Classification (by Distribution) 1 nerve affected >1 nerve affected symmetric Asymmetric Mononeuropathy Mononeuropathy multiplex Polyneuropathy CN 7 palsy Mononeuropathy I weakness in 112offace • When ONE peripheral nerve affected • Can be cranial nerve or spinal nerve • Causes: trauma, compression or entrapment • Lead to loss of that nerve function (motor, sensory, &/or autonomic) Mononeuropathy cont. quite common • Carpal tunnel syndrome • Cause: Median nerve entrapped in flexor retinaculum • Symptoms: numbness in lateral 3½ digits +/- weakness • Exam: in exams ATinel sign phalen sign irritated tap itsalready symptoms bringhandstogetherlike in thepicturecompressnerve strong Mononeuropathy cont. • Carpal tunnel syndrome • Diagnosis: clinical & nerve conduction study • Treatment: • wrist splint +/- NSAID • Steroid (local) injection • sometimes surgery stimulatebefore measureafter if itsslowthere iscompression Mononeuropathy Mononeuropathy multiplex Polyneuropathy Mononeuropathy multiplex just understand the concept • When more than one peripheral nerve affected simultaneously or sequentially • Can be cranial nerve and/or spinal nerve • Asymmetric • Disease example: • Vasculitis of vasa nervorum • Sarcoidosis • Diabetes mellitus Mononeuropathy Mononeuropathy multiplex A Polyneuropathy This is a nice a's Polyneuropathy slide • Generalized, symmetric & length dependent • Longest fibers affected first always affects longest nerves in the body • symptoms starts in the feet • Commonest cause is diabetes mellitus Polyneuropathy (diagnosis) • Largely clinical • Nerve conduction study • Confirm diagnosis • Classify it into (next slide) • Nerve biopsy rarely done Polyneuropathy can be divided into: we can tell this by a nerve conductionstudy Demyelinating neuropathy Axonal neuropathy Polyneuropathy (causes) Eachtypehas a set ofcauses y Axonal neuropathy y Demyelinating neuropathy • Metabolic/endocrine (commonest DM) • Guillain-Barre syndrome • Hereditary • Hereditary • Toxins/drugs • Vasculitis • Arsenic toxicity • Lymphoma • Vitamin toxicity • Alcohol Details not necessary Polyneuropathy (treatment) • Depends on cause/disease • Symptomatic treatment Lecture summary… Question 1 • Which of the following causes of weakness characterized by fasciculations? a. Stroke UM N b. Brain tumor U MN c. Amyotrophic lateral sclerosis d. Basal ganglia calcifications not part of motor passway Question 2 • A 60-year old man previously healthy presented with right sided weakness of 1 hour duration. MRI showed acute stroke. Which of the following is NOT expected in this man? a. Weakness 3/5 in right arm b. Difficulty speaking c. Hyperreflexia with spasticity d. Hypotonia in right leg no because it wouldn't snow in the 1st hour Question 3 • A 23-year old medical student was diagnosed with carpal tunnel syndrome. Which of the following is NOT characteristic of this condition? a. b. O c. d. Tingling sensation Positive Hoffman’s sign um ni Weakness in thumb abduction Down-going toes on plantar reflex normal Thank you & all the best [email protected]