In some cases, symptoms may include double vision, numb chin, back pain, leg weakness, sphincter-related problems, hydrocephalus, loss of urine control, and difficulty walking. Depending on where the tumor cells settle, leptomeningeal cancer can cause almost any neurological problem. Other symptoms that are less common cranial nerve abnormalities, spinal symptoms such as limb weakness and paresthesia, and bowel and bladder dysfunction. Diplopia is the most common symptom of cranial nerve dysfunction. Trigeminal sensory or motor loss, cochlear dysfunction, and optic neuropathy are also common findings. Spinal signs and symptoms include weakness, dermatomal or segmental sensory loss, and pain in the neck, back, or following radicular patterns.3 affected domains of neurological function:

Cerebral hemisphere (15%)
Cranial Nerves (35%)
Spinal cord and roots (60%)Signs reported:

headache
mental status change
confusion
cognitive impairment
seizures
hemiparesis
gait instability

Related Diseases
Parenchymal Disease occurs in 30-40% of those diagnosed with NM. The disease associated with the main functioning body of an organ, in this case the brain. acute cerebellar ataxia is a rare initial presenting feature of NM, particularly in gastric cancer. Paraneoplastic cerebellar degeneration (PCD) is a well-known cause of cerebellar ataxia associated with neoplastic disorders, and commonly, with positivity for various anti-neuronal antibodies. Bilateral sensorineural hearing loss caused by complications with the vestibulocochlear nerves from onset of NM 
Subacute Confusion: when functioning of the brain such as cognition deteriorates but at a less rapid rate than that of acute confusion

Causes
Leptomeningeal carcinomatosis occurs when the cancer cells invade the cerebrospinal fluid and spread throughout the central nervous system.
If the cytology remains negative and radiological studies are not definitive, consideration may be given to ventricular or lateral cervical spine CSF analysis based on the suspected site of predominant disease. Consideration of signs, symptoms, and neuroimaging can help with the placement to where CSF is drawn. Median time of diagnosis from initial primary cancer diagnosis is between 76 days and 17 months. Difficulties in diagnosis
NM is multifocal and CSF at a particular site may show no abnormalities if the pathological site is far away. Only 50% of those suspected with NM are actually diagnosed with NM and only the presence of malignant cells in the CSF is diagnosis conclusive. Techniques
MRI: Meningeal findings are described with the following characteristics: Nodular meningeal tumor, meningeal thickening >3 mm and a subjectively strong contrast enhancement. A smooth contrast enhancement of the meninges was judged to be typical for inflammatory, nonneoplastic meningitis. CSF cytology: is performed after drawing the CSF by lumbar puncture. Cytogenetic: measures chromosomal content of cells and fluorescence in situ hybridization which detects numerical and structural genetic aberrations as a sign of malignancy. This is especially useful for liquid tumors such as leukemia and lymphoma. Some of the techniques that achieve this are flow cytometry and DNA single-cell cytometry. However, cytogenetic only assist in diagnosis and is less preferred. Meningeal Biopsy: may be performed when all of the above criteria is inconclusive. Biopsy is only effective when performed at the region where theres enhancement on the MRI.