Neuro - PNS - Infectious Disease

Question 1

Lyme Disease

Answer 1

The spirochete, Borrelia burgdorferi is the transmissible causative agent in Lyme borreliosis. Although the disease can have numerous musculoskeletal manifestations it can also present with facial palsy, meningitis, encephalitis, radiculoneuritis, mononeuropathy multiplex or polyneuropathy.

Question 2

Lyme Disease - Epidemiology

Answer 2

• Most common vector -borne disease in the US
• Highest incidence in 5-10 year olds
• Incidence has been increasing over time and is most likely due to increases in the deer herd and expansion in the range of the vector.
• CDC reported 16,461 cases in 1996
• Although 80-90% of cases were from 8 states (CT, RI, NY, PA, NJ, DE, MD, WI) it has been reported in almost every state
• Prevalence varies, in 1996 it was 6.2/100,000
• in CT the rate was 94.8 per 100,000; in nantucket county it was 1247/100,000
• for 1997 and 1998, 12,801 and 16,801
• In 2002, number of new cases reported to CDC was 23,763
• Actual incidence may be as much as 10 times higher than that indicated

Question 3

Lyme Disease - Etiology

Answer 3

• disease carried by the Ixodes tics (deer tics)

* Natural reservoir: white footed mouse

Question 4

Lyme Disease - Pathogenesis

Answer 4

• Tic must feed for at least 24 hours to transmit
• Initial immune response due to bacteria lipoproteins binding to the TLR-2 on macrophages > release cytokines & generate bacterial nitric oxide
• Adaptive immune response via CD4 T cells and B cells > Borrelia Ab made, but the bacteria can escape these antibodies through antigenic variation
• antigenic surface protein V1SE is expressed in alternate forms allowing some bacteria to escape the immune response

Question 5

Lyme Disease - Early Presentation

Answer 5

• Weeks
• Spirochetes spread and multiple at bite site in dermis
• Skin lesion at the site of the tick bite, termed erythema migrans (Bullseye rash)
• Fever lymphadenopathy

Question 6

Lyme Disease - Disseminated Infection

Answer 6

• Weeks to months
• spread hematogenously
• Fatigue and flu like symptom
• Headache, stiff neck, nausea, vomiting, malaise, and chronic fatigue
• Aseptic meningitis
• Secondary to skin lesions, migratory joint and muscle pain, cardiac arrhythmias

Question 7

Lyme Disease - Persistent Infection

Answer 7

• Years
• Oligarticular arthritis, synovitis in 60% of untreated cases
• Late appearing cardiac symptoms in less than 15% of cases
• Cranial or peripheral neuritis, most frequent is facial palsy
• Encephalitis

Question 8

Lyme Disease - Diagnostic Testing

Answer 8

• Lumbar puncture: slightly lowered glucose
• Serologic tests
• specific IgG Ab (remain elevated indefinitely) - ELISA - western blot
• CT and MRI imaging when indicated

Question 9

Lyme Disease - Treatment

Answer 9

• Pharmaceutical
• Oral tetracycline
• Doxycycline
• CONTRAINDICATED in children (teeth discoloration) and pregnancy
• Penicillin when indicated

Question 10

Lyme Disease - Management with complications

Answer 10

• Jarisch-Herxheimer Reaction after treatment: increased temperature, sweatsm abd myalgia - resolves within 1-2d
• Re-infection (uncommon)
• Chronic or persistent infection with joint disease and neurological and cardiac manifestations

Question 11

Varicella Zoster

Answer 11

• Herpes zoster is a latent infection of dorsal root ganglion or cranial sensory nerve ganglia

AKA shingles

Question 12

Varicella Zoster - Epidemiology

Answer 12

• Most common viral infection of the peripheral nervous system
• Incidence is 3-5% cases per 1000 annually
• More common in the elderly, after 6th decade of life

Question 13

Varicella Zoster - Pathogenesis

Answer 13

• Initial chickenpox infection via respiratory transmission
• infectious up to 48 hours before onset of vesicular rash
• Varicella or varicella zoster virus (VZV) infection becomes latent in ganglia
• VZV is a DNA virus closely related to the Herpes simplex virus
• unknown mechanism of spontaneous reactivation of VZV
• Acute inflammatory reaction in isolated spinal or cranial ganglia
• Ganglion necrosis can occur
• virus progresses down the nerve to the skin and where it replicates in the epithelial cells
• cutaneous vesicular pattern following dermatome distribution
• risk factors include waning immunity

Question 14

Varicella Zoster - Presentation

Answer 14

• Initial itching, tingling, or burning sensation
• Zoster-associated pain: continuum of radicular pain from onset to resolution
• Erythematous maculopapular rash evolves into unilateral vesicular cutaneous eruption
• Segmental sensory loss
• delayed motor responses
• Can last 1-4 weeks (typical is 7-10 days)
• Typically 1-2 dermatomes are involved
• common is T3-L3
• zoster opthalmicus: CN V1 involvement

Question 15

Varicella Zoster - Diagnostic Testing

Answer 15

• Direct immunofluoresence of skin biopsy using antibodies to VZV
• Examination fo scrapings for multinucleated giant cells
• Antibody detection in the spinal fluids
• Isolation of the virus in tissue culture
• PCR detection of VZV DNA

Question 16

Varicella Zoster - Treatment

Answer 16

• Analesics
• Drying of the skin
• Soothing lotions
• Nerve blocks when indicated
• Acyclovir (shorten the infection)

Question 17

Varicella Zoster - Management with Complication

Answer 17

• Postherpatic neuralgia
• severely painful
• Opthalmic herpes with involvement of the cornea can result in blindness without antiviral therapy
• Ramsay Hunt Syndrome (pain and vesicles in external auditory canal), facial palsy, loss of tase in anterior 2/3 of tongue)
• encephalitis and cerebral angitis
• presents as headache, fever, photophobia, meningitis, vomiting
• Secondary bacterial superinfection due to excoriation of lesion after scratching

Question 18

Varicella Zoster - Prevention

Answer 18

• Vaccination with live attenuated virus
• VZ Ig to susceptible individuals at risk of developing complications
• Prophylactic antiviral therapy to patients at high risk
• VZV patient can transmit to seronegative individual resulting in chicken pox