黒崎 史朗

BACKGROUND: Central pain, characterized by neuropathic pain, can manifest due to injury to the superior spinothalamic tract. The brainstem includes sensory and motor pathways as well as nuclei of the cranial nerves, and therefore cancer metastasis in the region requires early intervention. Although stereotactic radiosurgery (SRS) is commonly employed for the treatment of brain metastasis, it poses risks of late complications like radiation necrosis (RN). RN exacerbates the progression of brain lesions within the irradiated area, and in the brainstem, it can damage multiple nerves, including the superior spinothalamic tract. Central neuropathic pain is often intractable and empirically managed with a combination of conventional drugs, such as serotonin-norepinephrine reuptake inhibitors (SNRIs) and anticonvulsants. However, their efficacy is often limited, leading to a decline in performance status (PS) and quality of life (QOL). CASE PRESENTATION: We present the case of a 53-year-old man diagnosed with stage IV lung cancer, referred to our palliative care team for managing severe central pain resulting from SRS-related RN in the pons. Despite administration of opioids, including oxycodone and hydromorphone, and adjuvant analgesics, the patient continued to require frequent use of immediate-release opioids. The addition of methadone alone proved successful in achieving optimal pain control. CONCLUSIONS: Provided that RN in the brainstem can lead to intractable neuropathic pain, it is advisable to avoid SRS for brainstem metastasis when possible. Add-on methadone should be considered as a viable pain management medication for patients experiencing unresolved central pain.

Tuberculous meningitis (TBM) is a rare disease in low-incidence countries like Japan, where general physicians have fewer experience with TBM. Despite its proper treatment and early improvement of the condition, TBM often causes paradoxical reactions (PRs), which can lead to severe complications such as stroke. As PRs in the brain are difficult to detect without regular neuroimaging surveillance and have a later onset than in other organs, delayed treatment can be fatal. We report a case of a 54-year-old, human immunodeficiency virus (HIV)-negative man who presented with TBM and miliary tuberculosis (TB) in an unconscious state. Standard anti-tuberculous therapy with adjunctive systemic high-dose dexamethasone brought rapid clinical and microbiological improvement, which allowed the dexamethasone to be tapered. However, he developed cerebral infarction with left hemiplegia due to a TBM-related PR five months after admission. Therefore, the initial high-dose dexamethasone was again added to the anti-tuberculous drugs, achieving the significant effects on the PR-related lesions. Anti-tuberculous drugs had been administered for 3 years and the dexamethasone was carefully tapered. Nevertheless, enlargement of PR-related lesions in the brain recurred 5 years later. Accordingly, the dose of corticosteroid was again increased, resulting in resolving the lesions. It is important to note that severe TBM may cause prolonged PRs, which require a long-term neuroimaging follow-up and anti-inflammatory drugs for the successful management of the TBM-related PR.