chronic cough is a frequent presenting complaint to not only the general practitioner but also the otolaryngologist and respiratory specialist .
diagnosis can be difficult , especially in primary care , but empirical treatment for common causes such as asthma , chronic obstructive pulmonary disease , gastro - oesophageal reflux disease , postnasal drip or drug - induced cough ( most commonly secondary to angiotensin converting enzyme inhibition ) is recommended when there are no associated worrying symptoms , and is successful in the majority of cases .
symptoms that may signify a rarer but more serious cause for chronic cough include the copious production of sputum , fever , sweats , unintentional weight loss , haemoptysis , clubbing , hoarseness and marked dyspnoea . here
we highlight a unique cause of chronic cough : the initial symptom of lymphoma compressing the brainstem .
a 69year - old gentleman presented to his general practitioner with a 3-month history of progressive unsteadiness . on further questioning
he also volunteered that these symptoms had been preceded by a chronic cough , which had no obvious precipitant , and which had failed to resolve . on examination he had truncal ataxia , to the point where he had difficultly remaining upright when walking , and exhibited gaze - evoked first - degree nystagmus in his left eye on looking to the right .
the patient had suffered an episode of labyrinthitis 10 years earlier , and so he was prescribed pharmacological therapy aimed at a presumptive diagnosis of a second episode .
successive trials of prochlorperazine , betahistine , cyclizine and arlevert were not noted to have any positive effect on the patient 's dizziness and he was referred for outpatient neurological opinion . by the time of specialist review , the patient 's symptoms had worsened and he now described periods of severe nausea , with progression of his ataxia to the point where he was unable to stand unaided .
he had also developed an area of hypoesthesia on the left side of his face .
eye movements were adjudged to be markedly abnormal with dysmetric horizontal saccadic movements in addition to his ongoing nystagmus . his right vestibular ocular reflex was reduced and his left upper limb movements lacked coordination .
gadolinium - enhanced magnetic resonance imaging ( mri ) of the brain revealed a homogenously enhancing , sharply demarcated 13 mm diameter lesion in the left posterior and lateral midbrain extending into the inferior cerebellar peduncle , with some adjacent oedema , suggestive of primary lymphoma ( see fig .  1 ) .
stereotactic brain biopsy confirmed diffuse large b - cell lymphoma ( dlbcl ) and subsequent bone marrow biopsy and computer tomography ( ct ) imaging showed no evidence of lymphoma at any additional anatomical site . 

figure  1:gadolinium - enhanced t1-weighted mri images ( panes lettered with coronal ( a ) , axial ( b ) and sagittal ( c ) sections ) showing a homogenous enhancement of a clearly demarcated lesion in the left posterior and lateral midbrain with extension into the inferior cerebellar peduncle . gadolinium - enhanced t1-weighted mri images ( panes lettered with coronal ( a ) , axial ( b ) and sagittal ( c ) sections ) showing a homogenous enhancement of a clearly demarcated lesion in the left posterior and lateral midbrain with extension into the inferior cerebellar peduncle .
the patient embarked on idaram ( idarubicin , cytarabine , methotrexate , dexamethasone ) chemotherapy followed by two rounds of high - dose methotrexate mono - therapy .
imaging following treatment showed radiological remission and this is also seen on recent scans , now 2 years later ( see fig .  2 ) .
while the symptoms of cerebellar dysfunction have largely abated since discharge , the patient has , however , been continually troubled by his cough . 

figure  2:compares initial t1-weighted gadolinium - enhanced mri images ( seen in panes on left hand side : a , c and e ) with those taken following completion of treatment ( panes on right : b , d and f ) . radiological remission is shown in the post - treatment images .
compares initial t1-weighted gadolinium - enhanced mri images ( seen in panes on left hand side : a , c and e ) with those taken following completion of treatment ( panes on right : b , d and f ) . radiological remission is shown in the post - treatment images .
otolaryngology assessment , including symptom review , medication history , endoscopic evaluation and chest x - ray , was unable to elucidate any cause for cough other than the presumed effects of the medullary lesion .
empirical trials of nasal steroids , nasal saline washes , high - dose proton pump inhibitor and inhaled bronchodilators were all unsuccessful .
coughing is a protective motor reflex under both voluntary and involuntary regulation , integrating physiological , psychological and social inputs .
studies in experimental animals have shown that vagal afferents signal peripheral sensory stimulation from the airways and lungs , and project centrally to the nucleus tractus solitarius ( nts ) with further projections between the nts and the medulla and pons . that such projections constitute a regulatory brainstem 
cough centre is a concept that has been extensively pursued ; attempting to determine the specific central pathways involved in the initiation and regulation of the efferent arc of the cough reflex .
the aetiology of chronic cough has been considered in a similar manner to the aetiology of chronic pain , with elements of both peripheral and central sensitization .
most of the common causes of chronic cough , and notably the classically described  diagnostic triad of asthma , gastro - oesophageal reflux disease and postnasal drip , arise primarily through the activation of peripheral vagal afferents , but with probable central maladaptation contributing to hyper - sensitization to peripheral stimuli .
pathological impingement of the dorsal medullary region of the brainstem is recognized as a neurogenic cause of chronic cough in cases of patients with chiari i malformations and cough may be the initial symptom .
however , to our knowledge , this is the first reported case of a lymphoma around the brainstem with chronic cough as one of the first symptoms .
it is difficult to be certain as to the mechanism of chronic cough induced by this lymphoma .
it may be that the expanding mass of the dlbcl compressed nearby nerve efferents serving the cough reflex , leading to aberrant hypersentization .
however , dlbcl can be an aggressive lesion and has been reported to present with focal neurology from local invasion into nerves .
it is possible , therefore , that the chronic cough in this case was caused by tumour infiltration into nerves rather than compression .
although clearly cerebral lymphoma is a very rare cause of chronic cough , we believe that clinicians in primary and secondary care should consider rare central causes of chronic cough in cases where neurological symptoms or signs are present , or in cases where empirical treatment for the more common causes of cough fails to provide symptomatic relief .
 we report a rare case of chronic cough as the presenting symptom of a primary brainstem lesion . 
 a 69-year - old gentleman presented with chronic cough followed by onset of progressive truncal ataxia , incoordination and nystagmus . 
 contrast - enhanced imaging showed a midbrain lesion extending into the cerebellum , confirmed as lymphoma by stereotactic brain biopsy . 
 the patient was successfully treated with chemotherapy , but his cough persists . 
 we present this case to highlight the possibility of a brainstem lesion as a rare central cause of chronic cough , and suggest that the diagnosis is considered in those with concomitant neurological symptoms . 