The Location of the Parasympathetic Fibres within the Vagus Nerve Rootlets: A Case Report and a Review of the Literature.

The vagus nerve has motor, sensory, and parasympathetic components. Understanding the nerve's internal anatomy, its variations, and relationship to the glossopharyngeal nerve are crucial for neurosurgeons decompressing the lower cranial nerves. We present a case report demonstrating the location of the parasympathetic fibres within the vagus nerve rootlets. A 47-year-old woman presented with a 1-year history of medically refractory left-sided glossopharyngeal neuralgia and a more recent history of left-sided hemi-laryngopharyngeal spasm. magnetic resonance imaging showed her left posterior inferior cerebellar artery distorting the lower cranial nerves on the affected left side. The patient consented to microvascular decompression of the lower cranial nerves with possible sectioning of the glossopharyngeal and upper sensory rootlets of the vagus nerve. During surgery, electrical stimulation of the most caudal rootlet of the vagus nerve triggered profound bradycardia. None of the more rostral rootlets had a similar parasympathetic response. This case is the first demonstration, to our knowledge, of the location of the cardiac parasympathetic fibres within the human vagus nerve rootlets. This new understanding of the vagus nerve rootlets' distribution of pure sensory (most rostral), motor/sensory (more caudal), and parasympathetic (most caudal) fibres may lead to a better understanding and diagnosis of the vagal rhizopathies. Approximately 20% of patients with glossopharyngeal neuralgia also have paroxysmal cough. This could be due to the anatomical juxtaposition of the IXth cranial nerve with the rostral vagal rootlets with pure sensory fibres (which mediate a tickling sensation in the lungs). A subgroup of patients with glossopharyngeal neuralgia have neuralgia-induced syncope. The cause of this rare condition, "vago-glossopharyngeal neuralgia," has been debated since it was first described by Riley in 1942. Our case supports the theory that this neuralgia-induced bradycardia is reflexively mediated through the brainstem with afferent impulses in the IXth and efferent impulses in the Xth cranial nerve. The rarer co-occurrence of glossopharyngeal neuralgia with hemi-laryngopharyngeal spasm (as seen in this case) may be explained by the proximity of the IXth nerve with the more caudal vagus rootlets which have motor (and probably sensory) supply to the throat. Finally, if there is a vagal rhizopathy related to compression of its parasympathetic fibres, one would expect it to be at the most caudal rootlet of the vagus nerve.

Solitary Primary Central Nervous System Lymphoma Mimicking Third Ventricular Colloid Cyst-Case Report and Review of Literature.

BACKGROUND: Primary central nervous system lymphoma is a rare malignant tumor of the central nervous system. It is associated with poor prognosis and accounts for 0.7%-0.9% of all lymphomas and only 0.3%-1.5% of intracranial tumors. Typically, these lesions are in the cerebral white matter near the corpus callosum, the central gray matter, the basal ganglia-thalamus-hypothalamic region, the posterior fossa and the periventricular region. Only 2 cases with pure third ventricular lymphoma have been reported in the literature. CASE DESCRIPTION: A 72-year-old female patient known to have type II diabetes mellitus treated with insulin, hypertension, chronic kidney disease, dyslipidemia, and obesity presented with a history of acute confusion and urinary incontinence. No headache was reported on admission, but previously she had intermittent mild headaches and generalized body aches. She had no history of visual symptoms. Her family said she was mildly confused and had memory difficulties that started acutely 2 days before presentation to the hospital. The patient had urgent computed tomography of the brain, which showed a hyperdense lesion in the region of the foramen of Monro. Pre-operative images diagnosed the case as colloid cyst, but post-operative histopathology proved the lesion to be primary CNS lymphoma. CONCLUSIONS: Eleven months after surgery, the patient is fully consciousness and oriented, with no memory issues or neurologic deficit. She is back to her baseline activities. We are reporting this case for the rarity of the disease and the unusual location of it.