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Neuro syphillis and hypothyroidism goiter mbbs note

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1. Neurosyphilis

Definition

Infection of the central nervous system by Treponema pallidum. It may occur at any stage of syphilis, especially in untreated infection and in people with HIV.

Types and clinical features

TypeUsual timingKey features
Asymptomatic neurosyphilisEarlyAbnormal CSF without neurological symptoms
Meningeal neurosyphilisWeeks to monthsHeadache, vomiting, neck stiffness, cranial nerve palsies, meningitis
Meningovascular neurosyphilisMonths to yearsSyphilitic endarteritis causing ischemic stroke, often in younger adults
General paresisYears laterProgressive dementia, personality change, psychiatric symptoms, tremor, dysarthria, seizures
Tabes dorsalisYears laterDegeneration of posterior columns and roots: sensory ataxia, lightning pains, absent reflexes, positive Romberg sign, bladder dysfunction, Charcot joints
Ocular/otosyphilisAny stageUveitis, visual loss, hearing loss, tinnitus, vertigo

Important signs

  • Argyll Robertson pupil: small irregular pupils that accommodate but do not react to light.
  • Tabes dorsalis triad: lightning pains, sensory ataxia, and bladder dysfunction.
  • General paresis: dementia with dysarthria, tremors, and abnormal pupils.

Diagnosis

  1. Serology
    • Screening: VDRL or RPR.
    • Confirmation: TPHA/TPPA or FTA-ABS.
  2. CSF examination
    • Lymphocytic pleocytosis.
    • Raised protein.
    • Reactive CSF-VDRL is highly specific, though not fully sensitive.
    • CSF FTA-ABS/TPPA is sensitive but less specific.
  3. Consider HIV testing in every patient with syphilis/neurosyphilis.

Treatment

First-line
  • Aqueous crystalline penicillin G, 18-24 million units/day IV, given as 3-4 million units every 4 hours or continuous infusion, for 10-14 days.
Alternative regimen
  • Procaine penicillin G 2.4 million units IM once daily plus probenecid 500 mg orally four times/day for 10-14 days.
Penicillin allergy
  • Penicillin desensitization is preferred, particularly in pregnancy.
  • Ceftriaxone may be considered in selected non-pregnant patients under specialist advice.

Jarisch-Herxheimer reaction

An acute febrile reaction within 24 hours after starting therapy due to spirochete destruction:
  • Fever, chills, headache, myalgia, worsening of lesions.
  • Treat supportively with antipyretics. It is not a penicillin allergy.

Follow-up

  • Clinical review and quantitative RPR/VDRL titres.
  • CSF follow-up may be considered if symptoms persist or serological response is inadequate.

2. Hypothyroidism

Definition

A clinical syndrome caused by deficient thyroid hormone production or action.

Causes

Primary hypothyroidism

  • Hashimoto thyroiditis: most common in iodine-sufficient areas.
  • Iodine deficiency.
  • Post-thyroidectomy or radioiodine therapy.
  • Drugs: amiodarone, lithium, interferon-alpha, antithyroid drugs.
  • Congenital thyroid dysgenesis.
  • Infiltrative disease: amyloidosis, sarcoidosis.

Central hypothyroidism

  • Pituitary disease causing low TSH.
  • Hypothalamic disease causing deficient TRH.

Clinical features

  • Fatigue, lethargy, weight gain.
  • Cold intolerance.
  • Constipation.
  • Dry coarse skin, hair loss, brittle nails.
  • Puffy face, periorbital edema.
  • Hoarse voice.
  • Bradycardia.
  • Menorrhagia, infertility, reduced libido.
  • Depression, impaired memory, slow speech.
  • Delayed relaxation of ankle jerk.
  • In children: impaired growth and intellectual development.

Investigations

ConditionTSHFree T4
Primary hypothyroidismHighLow
Subclinical hypothyroidismHighNormal
Central hypothyroidismLow or inappropriately normalLow
Other tests:
  • Anti-thyroid peroxidase antibodies in Hashimoto thyroiditis.
  • Lipid profile: hypercholesterolemia may occur.
  • CBC: normocytic or macrocytic anemia may occur.
  • Serum sodium may be low.

Treatment

  • Levothyroxine is the treatment of choice.
  • Typical full replacement dose in healthy adults: about 1.6 micrograms/kg/day.
  • Start low, often 12.5-25 micrograms/day, in elderly patients or those with ischemic heart disease, then titrate gradually.
  • Take on an empty stomach, usually 30-60 minutes before breakfast.
  • Monitor TSH about 6-8 weeks after starting or changing dose in primary hypothyroidism.
  • In central hypothyroidism, monitor free T4 rather than TSH.
  • If both adrenal insufficiency and hypothyroidism are suspected, give glucocorticoids before thyroid hormone to avoid precipitating adrenal crisis.

Myxedema coma

A life-threatening severe hypothyroid state.
Features
  • Altered sensorium/coma.
  • Hypothermia.
  • Bradycardia, hypotension.
  • Hypoventilation, hyponatremia, hypoglycemia.
Management
  • ICU care, airway and ventilation support.
  • IV levothyroxine, with or without liothyronine depending on protocol.
  • Hydrocortisone until adrenal insufficiency is excluded.
  • Treat precipitating cause, such as infection.

3. Goiter

Definition

Goiter is enlargement of the thyroid gland.

Classification

  1. Diffuse goiter
    • Simple/colloid goiter.
    • Graves disease.
    • Hashimoto thyroiditis.
  2. Nodular goiter
    • Solitary thyroid nodule.
    • Multinodular goiter.
  3. Functional classification
    • Toxic goiter: associated with hyperthyroidism.
    • Non-toxic goiter: euthyroid or hypothyroid.

Causes

  • Iodine deficiency.
  • Graves disease.
  • Hashimoto thyroiditis.
  • Multinodular goiter.
  • Thyroid adenoma or carcinoma.
  • Goitrogenic drugs: lithium, amiodarone.
  • Dyshormonogenesis.
  • Physiological enlargement in puberty and pregnancy.

Clinical features

  • Neck swelling moving on deglutition.
  • Cosmetic concern.
  • Compressive symptoms in large goiter:
    • Dysphagia.
    • Dyspnea.
    • Hoarseness.
    • Stridor.
    • Superior vena cava obstruction in retrosternal goiter.
  • Symptoms of hyperthyroidism or hypothyroidism may coexist.

Examination

Assess:
  • Diffuse versus nodular swelling.
  • Consistency, tenderness, bruit.
  • Cervical lymph nodes.
  • Retrosternal extension.
  • Signs of thyrotoxicosis or hypothyroidism.
  • Vocal cord function if hoarseness is present.

Investigations

  1. TSH is the initial test.
  2. Free T4/T3 if TSH is abnormal.
  3. Ultrasound thyroid to assess nodules and cervical nodes.
  4. Fine-needle aspiration cytology (FNAC) for suspicious or significant nodules.
  5. Radionuclide scan if TSH is suppressed to identify a hyperfunctioning nodule.
  6. CT/MRI if retrosternal extension or tracheal compression is suspected. Avoid unnecessary iodinated contrast in thyrotoxicosis.

Red flags for thyroid malignancy

  • Hard irregular nodule.
  • Rapid enlargement.
  • Hoarseness or vocal cord palsy.
  • Cervical lymphadenopathy.
  • Previous neck irradiation.
  • Family history of thyroid cancer.
  • Dysphagia, stridor, or fixed swelling.

Management

Depends on cause:
  • Iodine-deficiency goiter: iodized salt and iodine supplementation at population level.
  • Simple small euthyroid goiter: observation and periodic clinical/ultrasound review.
  • Hypothyroid goiter due to Hashimoto disease: levothyroxine where indicated.
  • Toxic multinodular goiter or Graves disease: antithyroid drugs, radioiodine, or surgery.
  • Large compressive, retrosternal, suspicious, or cosmetic goiter: thyroidectomy may be required.

One-line exam summary

  • Neurosyphilis: CNS involvement by T. pallidum, diagnosed with syphilis serology plus CSF findings, treated with 10-14 days of IV penicillin G.
  • Hypothyroidism: low thyroid hormone state, usually high TSH and low free T4 in primary disease, treated with levothyroxine.
  • Goiter: thyroid enlargement evaluated first with TSH and ultrasound; FNAC is used to assess suspicious nodules.
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