Persistent severe hypocapnia and alkalemia in a 40-year-old woman

Central neurogenic hyperventilation in conscious patients due to CNS neoplasm: a case report and review of the literature on treatment

Background

Central neurogenic hyperventilation (CNH) is increasingly reported in conscious patients with a CNS neoplasm. We aimed to synthesize the available data on the treatment of this condition to guide clinicians in their approach.

Methods

We describe the case of a 39-year-old conscious woman with CNH secondary to glioma brainstem infiltration for whom hyperventilation was aborted with hydromorphone, dexamethasone, and brainstem radiotherapy. We then performed a review of the literature on the treatment of CNH in conscious patients due to a CNS neoplasm.

Results

A total of 31 studies reporting 33 cases fulfilled the selection criteria. The underlying neoplasm was lymphoma in 15 (45%) and glioma in 13 (39%) patients. Overall, CNH was aborted in 70% of cases. Opioids and sedatives overall seemed useful for symptom relief, but the benefit was often of short duration when the medication was administered orally or subcutaneously. Methadone and fentanyl were successful but rarely used. Chemotherapy was most effective in patients with lymphoma (89%), but not glioma (0%) or other neoplasms (0%). Patients with lymphoma (80%) and other tumors (100%) responded to radiotherapy more frequently than patients with glioma (43%). Corticosteroids were moderately effective. Subtotal surgical resection was successful in the 3 cases for which it was attempted.

Conclusion

Definitive treatment of the underlying neoplasm may be more successful in aborting hyperventilation. Variable rates of palliation have been observed with opioids and sedatives. Treatment of CNH is challenging but successful in a majority of cases.

A case of central neurogenic hyperventilation without tachypnoea

Central neurogenic hyperventilation (CNH) is a rare condition, with 37 cases reported in the literature to date. The underlying mechanisms remain unclear. Primary central nervous system lymphoma (PCNSL) is the most common cause of CNH, with 17 cases reported so far. Among these, CNH was usually accompanied by tachypnoea. Only two cases, including the present case, showed CNH with normal respiratory rate. Here, we present a case of PCNSL-induced CNH in a 60-year-old man. Magnetic resonance imaging of the brain demonstrated hyperintensity of the left cerebral cortex, basal ganglia, corona radiata, midbrain, and ventral pons on fluid-attenuated inversion recovery. The patient complained of dyspnoea and showed hyperventilation without tachypnoea on admission or during hospitalization. Examining CNH cases without tachypnoea and comparing those cases to cases of CNH with tachypnoea might provide new insights into the mechanisms of CNH. Moreover, it should be remembered that CNH can occur without tachypnoea.

Hyperventilation and cerebrospinal fluid acidosis caused by topiramate

OBJECTIVE

To report a case of hyperventilation caused by topiramate therapy and propose a pathophysiologic mechanism for this disorder.

CASE SUMMARY

A 52-year-old woman with refractory seizure disorder was admitted to the burn care unit with burns over 10% of her body. Her seizure medications, unchanged and well tolerated for several months, included carbamazepine 1200 mg, lamotrigine 500 mg, phenobarbital 80 mg, and topiramate 150 mg per day. During hospitalization, despite a relatively normal arterial pH, the woman developed persistent hyperventilation, with respiratory rates up to 50 breaths/min. Alkalinization did not reduce the hyperventilation. Thoracic contrast-enhanced computed tomographic scan ruled out pulmonary embolism and persistent pneumonia. Salicylate and biguanide screening were negative; results of repeated thyroid and liver function tests were normal. Cerebral magnetic resonance imaging excluded a cerebral pathology. After cerebrospinal fluid (CSF) analysis showed acidosis (pH 7.14), topiramate was withdrawn and the patient's general condition rapidly improved. Forty-eight hours later, the CSF pH had increased to 7.26. The woman was discharged from the burn care unit on the 42nd hospital day.

DISCUSSION

Hyperchloremic normal anion gap metabolic acidosis, which can lead to hyperventilation, has been reported as an adverse effect of topiramate treatment. However, our patient had respiratory alkalosis. Concurrent etiologies of peripheral hyperventilation were excluded, leaving central neurogenic hyperventilation as the remaining etiology. Such central neurogenic hyperventilation associated with topiramate has previously been reported in intensive care. Our case report demonstrates CSF acidosis. Withdrawing topiramate reduced both CSF acidosis and hyperventilation. The mechanism of topiramate-induced CSF acidosis remains unclear. According to the Naranjo probability scale, the relationship of hyperventilation to administration of topiramate in our patient was probable.

CONCLUSIONS

Normal doses of topiramate may provoke central neurogenic hyperventilation, as a result of CSF acidosis. The acid-base status of critically ill patients receiving topiramate should be monitored carefully.

[Primary central nervous system lymphoma presenting with central neurogenic hyperventilation. A case report and review of the literature]

INTRODUCTION

Central neurogenic hyperventilation (CNH) in an awake patient is a rare entity.

OBSERVATION

We report here a 54-year-old patient who developed central neurogenic hyperventilation as the initial presentation of a primary central nervous system lymphoma located in the brainstem.

CONCLUSION

The patient's hyperventilation resolved completely with chemotherapy for primary CNS lymphoma. Most of the cases reported in the literature are related to a diffuse tumor of the brainstem with an intriguing overrepresentation of primary CNS lymphoma. The pathogenesis of CNH is discussed.