Question

A 71-year-old male with unresectable lung cancer went to a tumor clinic for a routine checkup. The only trouble he had experienced in the 6 months following his diagnosis was occasional coughing, slight shortness of breath, and a mild but nagging pain in the right side of his chest. He explained to his doctor that lately the right side of his face had been " feeling funny." His symptoms, upon closer questioning, included lack of perspiration on the right side of his face during her regular morning walks. Examination of the patient revealed a right pupil that was much smaller than the left, along with a drooping right eyelid. Recognized the patient's abnormal face and eye findings as Horner's syndrome, the doctor turned to the chest CT scan in his file to look for the cause. He knowingly nodded as he examined the copy of the scan, noting that the lung tumor, located in the medial aspect of the right upper lobe, had invaded the mediastinum and the ascending nerve tracts into the base of the neck.

1) What area or general structure(s) within the autonomic nervous system has the tumor invaded and compromised?

2) Using autonomic nervous system terminology, explain the reason for each of the three findings (lack of facial sweating on the right side, pupillary constriction, and eyelid droop)

3) Include a description of neural pathways and effector organs

Answer 1

Pateint is case of Horner syndrome .

Horner syndrome is charcterised by triad of Miosis ( constricted pupil) Anhydrosis ( absent sweating) and Ptosis ( dropping of eye lids ) also enopthalmos is presnt ( eyes is inside ) and loss of ciliospinal reflex

It is cause due to damage of sympathetic trunk in this pateint Pancoast tumour which is tumour of Apex of lung probably is most common cause for Horner .

Structures involved
1)Pancoast tumour invades the Stellate ganglion ( Cervicothoracic ganglion ) which is sympathetic ganglion and responsible for horner syndrome

Reason for Clinical findings and neural pathways of sympathrtic system
1)Miosis - Sympathetic nervous system activate the Alpha 1 receptor presrent on Dilater pupillae muscles and cause mydriasis ( dilatation of pupil ) .when sympathetic acyivity is not there then there is no action on dilator pupillae so miosis seen because M3 receptor on sphincter pupillae will cause comstriction of pupil.

2)Anhydrosis - Sweating is stimulated by Sympathetic cholinergic receptors (M3 action ) No sympathetic supply hence no sweating .

3)Ptosis -Sympathetic postganglionic fibres also join the occulomotor nerve from the plexus on the internal carotid artery in the wall of the cavernous sinus and are distributed through the nerve to the smooth muscle of superior tarsal (Mueller's) muscle.