A Practical Approach to Polyneuropathy SLOCUM DICKSON ANNUAL TEACHING DAY NOVEMBER 4, 2017

Transcription

1 A Practical Approach to Polyneuropathy SLOCUM DICKSON ANNUAL TEACHING DAY NOVEMBER 4, 2017

2 Disclosures Research support from Cytokinetics, Inc Catalyst, Inc Editorial fees from UptoDate.

3 Objectives Describe basic approach to patients complaining of numbness/pain/weakness in the extremities Review basic peripheral nerve anatomy Discuss characterization as an aid to Dx of PN Review important PN types seen in primary care Basics of treatment of neuropathic pain Indicate when a neurology consult may be needed

4 Case #1 72 year old woman reports two years of foot numbness and a feeling of walking on sponges. She denies pain and weakness PMH Hypertension Hypercholesterolemia Hypothyroidism Medication Lisinopril Atorvastatin Levothyroxine

5 Case #1 Exam Normal strength including toe flexors and extensors Reduced Achilles reflexes Vibration sense reduced at toes (3 seconds) Pinprick sense reduced to ankles Unsteady tandem gait

6 What now?

7 Problem Peripheral neuropathy, like headache, is a common clinical syndrome with numerous causes. Evaluating peripheral neuropathy, like evaluating headache, requires careful characterization.

8 Solution Characterize the neuropathy as completely as possible. Character offers clues to etiology. Characterization involves a series of careful assessments History Physical Nerve conduction studies Skin or nerve biopsy

9 Basics of nerve anatomy

10 Peripheral nerves formed from nerve roots Emerge from spinal cord at all levels Dorsal roots convey sensory fibers from body Ventral roots form motor nerve fibers

11 Peripheral nerves 3_Peripheral_Nerve_Histology.htm

12 Fiber types meters/ sec 3-5 m/s

13 Fiber types: IMPORTANT Myelinated fibers Unmyelinated fibers Voluntary muscle Pain Position sense Temperature Vibration sense Autonomic functions

14 Five things to know 1. Tempo 2. Pattern of deficits 3. Which types of fibers affected Motor Sensory Autonomic 4. Demyelinating or axonal 5. Other conditions/medical context

15 #1 Tempo Preston & Shapiro, 2014

16 #1 Tempo Acute GBS porphyria vasculitis Subacute CIDP paraneoplastic sensory neuronopathy vasculitic diabetic amyotrophy

17 Rule of thumb: Rapid progression = needs a neurologist

18 Tempo Chronic, progressive hereditary toxic metabolic Chronic, relapsing CIDP

19 #2 Pattern of deficits Clinical and D evelopmental Immunology Volume 2012, Article ID

20 #2 Pattern of deficits Distal symmetric: dying-back pathology Suggests toxic, metabolic or hereditary Mononeuropathy multiplex: deficits in individual nerve territories Suggests inflammatory (vasculitis, sarcoid) Often serious and treatable Overlapping mononeuritis multiplex Clue is asymmetric symptoms and signs

21 Clues to OMM Stepwise progression Asymmetry Clinically History Exam Electrically Always consider vasculitis

22 #3 Fiber type Sensory Motor Autonomic

23 #3 Fiber type Predominantly sensory Small fiber Painful, impaired pain and temp perception Preserved reflexes Prominent autonomic DM, HSAN, Fabry s, Tangier s Large fiber (demyelinating or axonal) Ataxia, areflexia Paraneoplastic sensory, pyridoxine, CIDP

24 #3 Fiber type Predominantly motor CIDP Charcot-Marie-Tooth (hereditary) NCS critical: demyelination

25 #3 Fiber type Prominent autonomic features Erectile dysfunction, orthostatic hypotension, bowel/bladder, gastroparesis DM, amyloid, porphyria, Mixed fiber type Majority of neuropathies Use other features to help esp clinical pattern of deficit/demyelinating vs. axonal

26 #4 Pathology: Demyelinating vs. axonal Most important distinction to make Clinical clues to demyelinating neuropathies severe weakness without atrophy proximal and distal weakness early loss of reflexes prominent proprioceptive, vibration loss Nerve conduction studies needed Marked slowing = demyelination Low amplitudes without marked slowing = axonal

27 Purpose of EMG Confirms polyneuropathy Helps characterize PN Character indicates CAUSE Characterizes by Pattern/symmetry Fiber type Myelin or axon

28 #5 Context Constitutional symptoms (weight loss, night sweats) Skin changes Vasculitis, HIV, lymphoma POEMS, Fabry s, vasculidites Bariatric surgery B1, B6, B12 deficiency

29 #6 Context Toxic exposure EtOH, chemo, vitamins, heavy metals, organophosphates History of relevant illness: DM, SLE, HIV

30 Summary statement: Subacute, asymmetric, sensorimotor, probably axonal Chronic, symmetrical, predominantly motor Subacute, asymmetric, sensory

31 Case #1 72 year old woman reports two years of foot numbness and a feeling of walking on sponges. She denies pain and weakness. Normal strength including toe flexors and extensors Reduced Achilles reflexes Vibration sense reduced at toes (3 seconds) Pinprick sense reduced to ankles Unsteady tandem gait Tempo?

32 Case #1 72 year old woman reports two years of foot numbness and a feeling of walking on sponges. She denies pain and weakness. Normal strength including toe flexors and extensors Reduced Achilles reflexes Vibration sense reduced at toes (3 seconds) Pinprick sense reduced to ankles Unsteady tandem gait Slowly progressive

33 Case #1 72 year old woman reports two years of foot numbness and a feeling of walking on sponges. She denies pain and weakness. Normal strength including toe flexors and extensors Reduced Achilles reflexes Vibration sense reduced at toes (3 seconds) Pinprick sense reduced to ankles Unsteady tandem gait Pattern?

34 Case #1 72 year old woman reports two years of foot numbness and a feeling of walking on sponges. She denies pain and weakness. Normal strength including toe flexors and extensors Reduced Achilles reflexes Vibration sense reduced at toes (3 seconds) Pinprick sense reduced to ankles Unsteady tandem gait Lengthdependent/distal, symmetric

35 Case #1 72 year old woman reports two years of foot numbness and a feeling of walking on sponges. She denies pain and weakness. Normal strength including toe flexors and extensors Reduced Achilles reflexes Vibration sense reduced at toes (3 seconds) Pinprick sense reduced to ankles Unsteady tandem gait Fiber type?

36 Case #1 72 year old woman reports two years of foot numbness and a feeling of walking on sponges. She denies pain and weakness. Normal strength including toe flexors and extensors Reduced Achilles reflexes Vibration sense reduced at toes (3 seconds) Pinprick sense reduced to ankles Unsteady tandem gait Sensory predominant Which sensory fibers predominate?

37 Case #1 72 year old woman reports two years of foot numbness and a feeling of walking on sponges. She denies pain and weakness. Normal strength including toe flexors and extensors Reduced Achilles reflexes Vibration sense reduced at toes (3 seconds) Pinprick sense reduced to ankles Unsteady tandem gait Mixed fiber type, sensory predominant

38 Case #1 72 year old woman reports two years of foot numbness and a feeling of walking on sponges. She denies pain and weakness. Normal strength including toe flexors and extensors Reduced Achilles reflexes Vibration sense reduced at toes (3 seconds) Pinprick sense reduced to ankles Unsteady tandem gait Distal, symmetric Length dependent Dying back

39 Summary statement CHRONIC, SYMMETRIC, LENGTH DEPENDENT, MIXED SENSORY POLYNEUROPATHY

40 Case 2 A 55 year old lady reports increasing gait difficulty. Problem dates from childhood: unable to run and jump normally. Scoliosus as child. No pain. Examination: Distal muscular atrophy. Grade 4/5 distal muscles, 5/5 proximal. Areflexia. Sensory perception diminished to all modalities distally.

41 Pes cavus Charcot-Marie-Tooth Disease and Related Inherited Peripheral Neuropathies Timothy J. Benstead and Ian A. Grant Can. J. Neurol. Sci. 2001; 28:

42 Character Chronic, progressive Motor more than sensory Symmetric

43 Case 2 Conduction velocity 14 m/s

44 Case 3 49 year old woman with history of hepatitis C admitted with 3 weeks of abdominal pain and weakness/paresthesias in the lower extremities.

45 Case 3 Generalized, severe, asymmetric weakness. Diffuse sensory loss to pin and vibration Reflexes depressed distally Lower extremity edema and pain Severe abdominal pain ESR 69

46 Character? Acute Sensory and motor Asymmetric Axonal or demyelinating?

47 Case 4

48 FIGURE 1-2 General Approach to Peripheral Nerve Disorders Russell, James A. CONTINUUM: Lifelong Learning in Neurology23(5, Peripheral Nerve and Motor Neuron Disorders): , October doi: /CON Estimated prevalence of common polyneuropathy categories.modified with permission from Visser NA, et al, Neurology American Academy of Neurology. neurology.org/content/84/3/259.full. 48

49 Neuropathy in Type 1 DM: Control matters

50 Pathogenesis (and treatment) of PN in Type 2 DM is more complex 90% of diabetes risk is linked to obesity 90-95% of diabetes is type 2 Treating hyperglycemia in type 1 reduces incidence of PN by 60-70% Treating hyperglycemia in type 2 reduces incidence of PN by 5%

51 What causes PN in type 2 DM? Patients with type 2 DM are more likely to have PN if other components of MetS are present Wiggin, et al, 2009: 427 patients with type 2 DM and mild to moderate PN: Elevated triglycerides correlated with loss of sural nerve myelinated nerve fiber density independent of disease duration, age, diabetes control, or other variables

52 Elevated triglycerides correlate with progression of diabetic neuropathy Hemoglobin A1C did not differ between stable PN and rapidly progressing PN Wiggin TD, et al Diabetes 2009;58:

53 Lipid-lowering agents are associated with a lower incidence of PN in type2 DM Davis, et al. Diabetologia 2008;51: Observational cohort Fremantle Diabetes Study 531 individuals with type 2 DM followed for 6 years Fibrate and statin use were associated with significantly reduced risk of incident neuropathy (HR 0.52 (95% CI ) and HR %CI

54 The metabolic syndrome and neuropathy: Therapeutic challenges and opportunities Hyperglycemia & hyperlipidemia incite feed-forward cycle of cellular damage, production of reactive oxygen species, oxidative stress, mitochondrial and ER dysfunction. Insulin resistance incites inflammation. Annals of Neurology Volume 74, Issue 3, pages , 9 OCT 2013 DOI: /ana

55 Basic work up AAN Practice Parameter Vitamin B12 Methylmalonic acid if B12 is under 350 TSH SPEP HemoglobinA1C or 2 hour glucose tolerance test

56 Patient counseling in PN Daily foot inspection Fall prevention Shoe selection Avoid low lighting Bilateral railings on stairs PT Walking aid Reinforce at each visit.

57 AAN Practice Parameter: Treatment of PN Pain

58 TABLE 1-9 General Approach to Peripheral Nerve Disorders Russell, James A. CONTINUUM: Lifelong Learning in Neurology23(5, Peripheral Nerve and Motor Neuron Disorders): , October doi: /CON Neuropathy Characteristics Suggesting the Need for a More Intensive Evaluationa 58