- Herpes zoster oticus (Ramsey- Hunt syndrome).

Herpes zoster oticus

(Ramsey-Hunt syndrome)

-Aetiology:-

• herpes zoster viral infection of the geniculate ganglion of the facial nerve.
• It is caused by reactivation of herpes zoster virus that has previously caused chickenpox in the patient.

-Clinical picture:-

• Pain in and around the ear
• vesicles on the auricle and in the external auditory canal
• Lower motor neuron facial nerve paralysis due to affection of the geniculate ganglion of the facial nerve.
• May be associated with sensory-neural hearing loss and vertigo due to affection of the cochleo-vestibular nerve (Ramsey-Hunt syndrome).

-Treatment:-
1.Anti-viral therapy as acyclovir (oral and local).
2.Corticosteroids (oral and local) in severe cases with affection of the facial and or cochleo-vestibular nerves.

Return to list of medical syndromes here

- Investigations for diagnosis of poisoning.

Investigations for diagnosis of poisoning

There are general & toxicological measures ......

• ECG.
• Urea & electrolytes , lab glucose, anion gap /- lactate & osmolal gap.
• Liver function Tests & Clotting (paracetamol, anticoagulants).

• Arterial Blood Gases.

• Drug levels (at appropriate interval: Paracetamol, salicylates; others: theophylline, digoxin, lithium, anti-epileptics if it was likely that they had been taken).

• Comprehensive toxicology screens not normally indicated in the emergency treatment.
• Carboxyhaemoglobin levels if carbon monoxide suspected.
• Urinalysis , save sample for possible toxicological analysis.

• Rhabdomyolysis , save sample for possible toxicological analysis.

• Chest X-Ray if pulmonary oedema/aspiration suspected.

- Types of Poisoning.

• Deliberate متعمد
  
  • Overdose as self-harm or suicide attempt.إنتحار
  • Child abuse .
    
  • Munchhausen's syndrome :Factitious disorder, Hospital addiction syndrome(e.g psychic patient).
  • Third party (attempted homicide, terrorist, warfare).
  
  
• Accidental عن غير قصد
  • Most episodes of paediatric poisoning.
  • Dosage error.
  • Iatrogenic
  • Patient error
  • Recreational use.
  
  
• Environmental:
  • Plants
  • Food
  • Venomous stings/bites.
  
  
• Industrial exposures.

- cornea.

cornea

* Definition :

It is a colorless (transparent) structure

covering the anterior 1/6 of the eye ball.


*Development of the cornea:

• Surface ectoderm forms the epithelium of the cornea.
• Mesoderm gives rise to the corneal stroma.
• Neural crest cells gives rise to the corneal Endothelium.

**Characters of the cornea :-

- colorless (transparent) structure and has a smooth surface.

- A vascular structure.

- Highly innervated by non-myelinated trigeminal nerve fibers.

-The most powerful refractive media of the eye

( 42+ diopters ).

- Diameter :-

• Horizontal = 12mm 
• vertical = 11mm Why…?

Due to scleral overlapping on upper

& lower sides of the cornea.

- It is not uniformly curved How…?

>>the central or optical zone having a smaller radius of

curvature than the peripheral parts,and the

posterior surface is more strongly curved than the anterior.

>> Ant radius of curvature = 7.7 mm 

>> Post radius of curvature = 6.6 mm

>>Thus the cornea is thinner (0.6 mm) at its

center than near its margin (1 mm).

see you,

Dr Ibrahim

- gonioscopy.

In the name of Allah

to know the principle of goniolens we

must know some important information.....

- There is an angle called critical angle which need  rays come from media of high refractive index to media of low refractive index at this angle no refraction occur.

- When rays come from the angle between cornea and  iris outward to air as it has total internal reflection as there is critical angle so don't released to air .

- Total internal reflection as rays fall with angle is more than critical angle.
- corneal R.I = 1.38
- Air R.I = 1.00

- Goniolens eliminates the total internal reflection by replacing the cornea-air interface  by a new geniolens-air interface that has  higher R.I (n=1.50) than
that of the cornea and the tear.



-uses :-
used for viewing the anterior chamber angle of the eye for evaluation, management and classification of  normal and abnormal angle structures which is important in glaucoma management and evaluation.

- Contraindications for gonioscopy:-

• Hyphaema.
• Compromised cornea (e.g corneal ulcer).
• Lacerated or perforated globe.

Thanks alot

Dr Ibrahim