Bilateral ptosis: An unusual presentation of mid brain tuberculoma

Abstract

Central nervous system tuberculoma can have different clinical manifestations like headache, seizures, papilledema or other signs of raised intracranial pressure depending up on the site and number of tuberculoma. We report a case of 56 year old female reported with history of bilateral asymmetric ptosis of one month duration,with no other neurological defecit. Magnetic resonance imaging (MRI) brain revealed well defined ring enhancing lesion in the medial aspect of left hemi midbrain with diffuse disproportionate perilessional edema. Contrast Enhanced Computed Tomogram (CECT) of chest and abdomen revealed features of disseminated tuberculosis. She was diagnosed as a case of disseminated tuberculosis and started on antitubercular therapy with steroids and the ptosis almost resolved after 01 month of antitubercular therapy. Our case report is unique in the sense that only few cases of midbrain tuberculoma causing occulomotor abnormalities are reported in literature.

Introduction

Tuberculosis continues to be a serious public health menace in developing countries especially in HIV-affected population. Central nervous system (CNS) tuberculosis develops in about 1% of individuals with Mycobacterium tuberculosis infection, including meningitis, tuberculoma, abscess, or other manifestations.^{1, 2} It is the most dangerous and devastating form of tuberculosis causing significant mortality and morbidity, despite antitubercular therapy. Tuberculoma, one of the forms of CNS tuberculosis, comprises about 40% of all intracranial space occupying lesions. Isolated midbrain tuberculoma is a very rare entity with only 5%–10% of CNS tuberculoma.^{3, 4} We report a rare case of a 56-year-old woman presented with bilateral asymmetrical progressive ptosis of one month duration; magnetic resonance imaging (MRI) revealed a ring-enhancing lesion in the left hemi-midbrain with perilesional edema, diagnosed to have tuberculoma on magnetic resonance spectroscopy (MRS); contrast-enhanced computed tomogram (CECT) of the chest and abdomen revealed features of disseminated tuberculosis.

Case report

A 56-year-old female patient, without any previous comorbidities, presented with the history of ptosis for 1-month duration with some diurnal variation. She denied any history of fever, vomiting, headache, or weakness of the upper limb or lower limb. She gave the history of multiple visits to ophthalmologists, undergoing evaluation for the same without any relief, and finally referred to the medicine department. On examination, she had visual acuity of 6/6 in both eyes. The pupils were reacting equally to light on both sides. Bilateral asymmetric ptosis was present RT>LT. External ocular movements were equal in all six cardinal positions. There was no nystagmus or relative afferent pupillary defect (RAPD). Her fundus examination was normal. No other focal neurological deficit was present. Forward arm abduction test was negative. She was planned for further workup for ocular myasthenia based on the history and clinical examination. MRI of the brain revealed well-defined T1 isointense and T2/FLAIR peripheral intermediate signal intensity with central hyperintensity nondiffusion restricting ring-enhancing lesion measuring 9 × 8.5 mm in the medial aspect of the left hemi-midbrain with diffuse disproportionate perilesional edema. MRS revealed a lipid lactate peak with in the lesion at 1.25 ppm, increase in choline creatinine ratio, decrease in NAA at 2 ppm, and decrease in NAA–choline ratio suggestive of tuberculoma. She underwent lumbar puncture, and cerebrospinal fluid analysis was normal including adenosine deaminase, and mycobacterium tuberculosis complex (MTB) polymerase chain reaction (PCR) was negative. Her HIV status was negative. Her erythrocyte sedimentation rate (ESR) was 56 mm/h, and mantoux was 14 mm of induration. Hematological and biochemical parameters were normal. CECT of the chest and abdomen revealed retroperitoneal lymphadenopathy with partly calcified mediastinal and hilar lymphadenopathy and fibrocalcific opacities in both lung apices, features of disseminated tuberculosis. Based on the clinical and radiological findings and other collaborative evidences and endemicity of tuberculosis in India, she was diagnosed as a case of disseminated tuberculosis. She was started on intravenous dexamethasone 0.4 mg/kg converted to oral dexamethasone after one week, tapered over next four weeks, and antitubercular therapy consisting of isonazid (300 mg), rifampicin (600 mg), ethambutol (1000 mg), and pyrazinamide (1500 mg). She showed dramatic clinical response with complete resolution of ptosis after one month of antitubercular therapy. MRI of the brain after 2 months showed reduction in the size of the lesion with complete resolution of perilesional edema. Presently, she is continuing on antitubercular therapy under regular follow-up, and the plan is to continue antitubercular therapy for 18 months.

Discussion

Neurotuberculosis accounts for 5%–15% cases of extrapulmonary tuberculosis. Intracranial tuberculoma are most commonly found in the cerebral and cerebellar hemisphere due to their rich blood supply. Isolated midbrain tuberculomas are rare, but depending up on the number and site of lesion, perilesional edema can have different clinical manifestations. Kumar et al⁵ reported a patient presenting as isolated bilateral ptosis due to midbrain tuberculoma. The other presentations of midbrain tuberculoma mentioned in the literature were pontine tuberculoma with horizontal gaze palsy,⁶ bilateral internuclear ophthalmoplegia,⁷ one-and-a-half syndrome,⁸ eight-and-a-half syndrome,⁹ and bilateral ptosis without upward gaze palsy¹⁰

The clinical findings of the patient involving third nerve correlates with location of the tuberculoma with perilesional edema, likely due to the involvement of caudal central subnucleus without affecting fibers innervating superior recti muscle (Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9).

Fig. 1.

Ring-enhanced lesion in the midbrain.

Fig. 2.

Ring-enhanced lesion in the midbrain.

Fig. 3.

Bilateral asymmetric ptosis.

Fig. 4.

Complete resolution of ptosis after one month of antitubercular therapy.

Fig. 5.

CECT of the chest and abdomen showing fibrocystic opacities suggestive of disseminated tuberculosis. CECT, contrast-enhanced computed tomogram.

Fig. 6.

CECT of the chest and abdomen showing hilar lymphadenopathy suggestive of disseminated tuberculosis. CECT, contrast-enhanced computed tomogram.

Fig. 7.

CECT of the chest and abdomen showing retroperitoneal lymphadenopathy suggestive of disseminated tuberculosis. CECT, contrast-enhanced computed tomogram.

Fig. 8.

Reduction in the size of lesion after 2 months of antitubercular therapy.

Fig. 9.

MRS showing lipid lactate peak and decrease in NAA–choline ratio. MRS, magnetic resonance spectroscopy.

In our patient being immunocompetent, we considered a differential diagnosis of neurocysticercosis, brain tumor, brain abscess, and metastasis. CNS tuberculomas are most often diagnosed based on clinical presentations and correlating imaging evidences. The role of stereotactic biopsy is limited because of difficulty in accessing the site and fear of aggravation of neurological deficits. The MRI features of tuberculoma depend on whether the lesion is caseating or noncaseating. The noncaseating granulomas are usually hypointense on T1-weighted images and hyperintense on T2-weighted images, whereas caseating tuberculoma, isointense to hypointense on T1- and T2-weighted image with isointense to hyperintense rim on T2-weighted images. Tuberculoma appears as ring-enhancing lesion after contrast administration with diameter ranging from 1 mm to 5 mm with varying degree of perilesional edema. In neurocysticercosis, on MRI, the wall is thick, hypointense, and often multiple and the scolex may be visible and usually does not cause extensive perilesional edema. Primary brain tumors are very large in size, and metastatic lesions are typically subcortical with nodular ring pattern of enhancement with very severe perilesional edema. Ring-enhancing lesions caused by brain abscess are commonly located at the gray–white matter junction, and the ring enhancement is usually thin and smooth. MRS is fairly accurate in differentiating tuberculoma from other infective etiologies. In our case, MRI of the brain revealed well-defined ring-enhancing lesion in the medial aspect of the left hemi-midbrain with perilesional edema and MRS was suggestive of tuberculoma with CECT chest and abdomen and other supportive evidences favoring features of disseminated tuberculosis. The response to antitubercular treatment was dramatic with complete resolution of ptosis after 1 month.

Only few cases of midbrain tuberculoma with isolated occulomotor involvement are reported in literature. The treatment of tuberculoma is antitubercular therapy. A course of antitubercular therapy for one and half year is sufficient¹¹. In most of the cases, clinical and radiological findings along with other collaborative evidences are sufficient to start treatment. Steroids are indicated in cases of extensive perilesional edema causing neurological deficits. Physicians and ophthalmologists should also consider a rare possibility of midbrain tuberculoma in evaluating a case of ptosis.

Declaration of patient consent

The authors certify that they have obtained consent from the patient. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Conflicts of interest

The authors have none to declare.